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-   -   First effort drip bucket system 14 headed to 20! (http://www.hydroponicsonline.com/forums/showthread.php?t=3119)

MontyJ 06-18-2014 12:17 PM

First effort drip bucket system 14 headed to 20!
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Hola to All,

A real experiment, LoL. First time hydroponic effort. Pics show some efforts and results so far.

The idea was a "compromise" system, i.e. a variety of plants, knowing I could not get super yield or quality out of all of them, but hopefully something edible. And it works!

I live on the edge of the sonoran desert. I have a growing season all year long, but the summers are super hot. And so far, I have not solved the nutrient cooling problem. I have measured the inside of the buckets at 104F during the hot part of the day. Yet, amazingly, the plants continue to grow and produce tomatoes and bell peppers, tho the bell peppers are stunted.

I have a new butternut squash and cucumber plant now growing in the buckets and they, so far, are looking good tho blooms only at this point. During cooler weather, I had great crops of red and bibb lettuce, along with a successful test of several green onion plants, which I plan on doing more of when I get some proper nets for the pots so finer media won't drop into the return system.

I started the first bucket on Jan 6, 2014. I gradually added buckets and am up to 14 now, with room for a total of 20 on the base of this old fountain on my patio. This is a rental property, so I cannot make any drastic changes.

The white wrapping on the buckets and the minifridge is called "Panda Film", which is just a plastic sheeting white on one side, black on the other. This of course keeps light out of the buckets and the white reflects a little, but not enough, heat away from the buckets.

My summer feed cycle is 30 minutes ON, 30 OFF. The return line flow is helped by a small pump because the gravity pressure is too low to get all the nutrients in the buckets back to the reservoir quickly. I do need a larger reservoir, so am looking at a 150 qt cooler. This one is 120 qt.

Ok, that is a start, so here are the pics.


[Edit] Main crop is tomatoes. Have Cherry, Grape, Salad, and normal varieties. The "Grape" tomato is the best tasting out of all of them.

Also, you can see a failed attempt at a Peltier cooling unit on the lid of the reservoir. The Peltier thing works, but simply cannot draw off enough heat fast enough, even using a 400 W peltier module. My calculations now indicate I need 16,000 BTU, or 1.5 ton cooling system to keep the nutes at around 70F. Uggghhh!

Stan 06-18-2014 09:26 PM

That's a very nice setup. Can you post more pics? I might try that to grow watermelon and cantelope for next year.

GpsFrontier 06-19-2014 01:27 AM

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Hello MontyJ,
I live in the desert also. Lake Havasu city AZ (the Mohave desert). We typically reach 120 Ferinheight by late summer. The last month has been in the 102 to 110 range and it's not even July yet. Growing in the heat has been my greatest challenge. First thing I see is that other than the reservoir, nothing looks insulated. Ya, the panda plastic helps reflect light, but it's not insulation. I would first suggest wrapping bubblwrap (Reflective) insulation tightly around each bucket. Like in these links:

Reflectix 25-ft x 24-in Reflective Insulation
Cool Shield Bubble Rolls and Pallet Covers

I also attached a picture of a pepper plant I have in a similar bucket wrapped with the bubble wrap insulation. Make sure to wrap it tightly. I used velcro to hold it snug. But you can also use a spray (contact cement) adhesive, and probably would be better.

Second thing I see is you have your buckets sitting on a wall. That wall absorbs heat from the sun all day long, and it radiates into your buckets from the bottom. You'll also notice in the picture of my bucket, that I have it sitting on top of a one inch thick piece of Styrofoam. Styrofoam is an insulator and blocks heat coming up through the bottom. The Styrofoam I used is a high density blue-board type, because I already had a bunch of it. But any regular white Styrofoam will do as well. Just make it an inch thick, or two 1/2 inch thick piece to get one inch thickness. Also it may be hard to see in the picture, but I also cut pieces of Styrofoam to place on top of the buckets to block the top of the buckets from the sun's heat as well.

Third thing I see is all those black return lines in direct sun. That is a great way to heat up your water (opposite of what you want). As a test, lay a garden hose with water inside of it out in the sun for an hour or two, then turn it on and hold your hand in the water that comes out. It will be extremely hot, and most garden hoses aren't even black. You get the same effect with the black Polly irrigation tubing. Cover all the tubing to the buckets and back to the reservoir with pipe insulation. If you need to, wrap the pipe insulation with white duck tape to hold it tightly in place.

Ya, I would recommend a larger reservoir, however they don't make coolers all that big, and they cost a fortune (here anyway). I haven't built one yet, but I have designed what I call a cooling box. It's essentially a costume built ice chest. It's designed to place a container your using for the reservoir in it, while acting like an ice chest to hold in the cold like an ice chest, and you can build it any size and shape you need. Here is a link to the design plans on my website: Nutrient Reservoir Cooling Box

Also I haven't drawn up designs for it yet, but I have plans to build and test what I call a reverse swamp cooler. If your familiar with swamp coolers, you know the water is nice and cool (mid to low 60's Fahrenheit) after running through the pads (even in high heat). The idea is to use this cool water to cool the nutrient solution. Either by placing the nutrient solution reservoir directly in the reverse swamp cooler reservoir, thus cooling by direct contact with the nutrient reservoir container. Or by pumping water from the reverse swamp cooler through coils placed inside the nutrient solution reservoir, preferably while it's inside the cooling box to insulate the nutrient reservoir from outside heat, and keep the cool in. If you would like to try it, and need help with the concept or designing it, contact me by e-mailing me at the address on my website so I can send you drawings to explain it better.

Do you add ice to your reservoir, if not the temp will never go down without some type of cooling, even with good insulation. The insulation just helps hold the cold in longer.

MontyJ 06-19-2014 09:05 AM

Those are some great ideas!

Being in Mexico, retired, and on a budget, I tend to do things incrementally, out of necessity. While we do have a Home Depot, it is not near as complete as those in the USA. Insulation, for example, is almost unheard of here on a consumer level. I have not checked at the Home Depot in a larger city like Hermosillo yet; they may have a better stock situation.

I have been trying to find some of that hard insulation to build a "cover" for the reservoir and the mini-fridge. I had not thought of putting some sheet material under the buckets; that is another incremental thing that will certainly help.

Part of my issue, which I didn't go into in my system description, is that I started this project in conjunction with a solar panel (100W) as my power supply. The idea (I do a blog for South-of-the-Border folks about the hydroponics and solar stuff) was to make the hydroponics totally "off-grid". I succeeded as far as the pumps, timers, sensors, and bubbler, but when I put in the mini-fridge, I had to plug into household grid power. 100W handles the hydroponic stuff just fine, but any serious cooling efforts need a boost beyond that. That is why I did the Peltier cooler tests; they were run on 12V and could be powered directly from the solar system; not full time of course, but I had hoped to be able to run it intermittently. No way in this heat, LoL.

The Igloo 150 qt cooler is reasonable on Amazon/eBay, but way to expensive here (almost double that!). I see a price of $95 for one with free shipping, so had my eye on that one. Of course another factor is the potential customs duty when crossing the border back into Mexico if I am over my 'limit'.

I had read a little about 'swamp coolers', but wanted to try all the little incremental things first. I think wrapping the buckets and tubing will help tremendously. And if I do that, I can probably get rid of the Panda wrap as well.

Yes, had done the "frozen water bottle" ice thing. My poor refrigerator/freezer had been running overtime to try to keep up with the load, not to mention the increased electric bill. Thankfully the Mexican govt subsidizes the electricity here a bit during the summer or it would be a deal killer.

Again, thanks for the great ideas and offer of more info! This gave me some great ideas I can have in place for next years 'heat wave', LoL.


MontyJ 06-19-2014 09:10 AM


Originally Posted by Stan (Post 11967)
That's a very nice setup. Can you post more pics? I might try that to grow watermelon and cantelope for next year.

Being "water" intensive, those fruits should do very well in a hydroponic setup!

Will put up some more pics today.

MontyJ 06-19-2014 10:56 AM

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Originally Posted by Stan (Post 11967)
That's a very nice setup. Can you post more pics? I might try that to grow watermelon and cantelope for next year.

Ok, some more pics.

1 - Return feed plumbing details. I could have put the thru-wall fittings on the bottom of the bucket for more complete drainage, but wanted the option to put the buckets on a flat surface with no 'edge' if needed.

2 - 6-net pot lid layout. I also have 3 x 3.5" pots and now 1 x 6" in the lid. Noob mistakes had me leaving plants in the small pots too long; I could not transplant to larger pots w/o damaging roots. Now I put the seedlings directly in the larger net pots. Tomatoes need 6" or larger, can use the 3.5" for lettuce.

3 - Early layout w/o trellis supports. We get some very high winds in this location, so I put large rocks in the buckets (sterilized, of course!) to keep them from blowing off the foundation. With the trellis setup I now have, I am going to get rid of the rocks; they are a huge heat 'collector' I can do w/o!

4 - Example of the lettuce crops I was getting during 80-85F temps. Now that I am in the 95-100F days, it is too much for lettuce.

5 - A test of green onions in a 3.5" net pot. I had to 'double up' on the pots to reduce the perlite media from dropping into the return line. I do have 'filters' on the thru-wall connectors on the inside, but they stop the larger clay pellets only.

6 - An overall view of the layout with tomato trellis supports added.

7 - Equipment used and Peltier test. I also use the Altronics 50 event timer board. So I can do 2 events/hour for 24 hours. Also have a temp controller (sensor went out the other day, so have a new one on order) to monitor the nute and chiller temps. The tubing out the lid of the reservoir is the feed supply via submersible pump. The return line is plumbed to the normal drain port of the cooler on the bottom far end (not shown).

8 - Here is the current internal plumbing of my mini-fridge chiller experiment. The tubing is very thin-walled 1/2" tube. I realize it is not as good a heat transfer as stainless steel or titanium, but that stuff is expensive! There is about 50' of the tubing coiled up in that 5 gal water jug, which is then filled with water. The other water jugs are to help stabilize the temps. I can of course put frozen water bottles in to help the cooling process. The compressor on this puppy runs full time, which is not good. Not sure if I should modify the freezer compartment/coil/sensor...

9 - Bucket wrap and trellis support details. Every other bucket has the pvc pipe support. It is attached to the bucket using a coat hanger at the top and bottom of the bucket. Since I cannot do any drilling or other mods to the old water fountain itself, I have to make everything self-supporting...portable if you will. The whole thing, once you get more than a few buckets, is surprisingly sturdy.

10 - Trellis details. PVC pipe is relatively (to wood) cheap here. I use 1" pipe with some angle adapters at the top and simply bolt the thing together. No glue used as I need to be able to take it apart easily.

Lots of noob mistakes made:

- Used too small of net pots and did not transfer the plants soon enough as they got bigger.
- Did not (initially) drain the buckets fast enough. I had one tomato plant develop root rot and it had to be destroyed, system cleaned, etc.
- Did not get the right nutes for the very hard water here. I am going to have to get a RO system and then treat with extra calcium, magnesium supplements.

I am a proponent of OJT (on the job training...old Air Force habit, LoL), or learn by doing. I was told I would "burn" the lettuce if I tried to grow it along with nute levels aimed at tomatoes. Well, I throttled back the PPM to the lower range for tomatoes, and my lettuce did not go up in flames! I realize it is a 'compromise' setup, trying to grow a variety of things in a single system. But it can be done. I don't get maximum tomato yield, of course. But my goal was to walk out my door and be able to pick lettuce, onions, tomatoes, bell peppers as a minimum for a great salad. I can do that, except in summer the lettuce isn't going to happen with this setup.

I am testing with some cucumbers and butternut squash. The leaves and vines and blooms are going crazy, but yet to get any veggies on them. I did plant them late.

It is an experiment on a compromise setup. So far I am encouraged, given I have not solved my summer heat problem, and have some serious water problems. I do not flush the system as often as I should, and I go against the rules by adding fresh nutes to older nutes. It ain't by the book, but I need to learn the hard way!:eek::cool:


MontyJ 06-22-2014 12:05 PM

First, a big THANK YOU to everyone that posted tips, hints, and constructive comments!

As you may have gleaned, I have 3 major problems:

1. Summer temps
2. Very, very hard water, at 700+ PPM
3. Too small a reservoir for my current, or future plants (14 buckets, headed for 20)

1) After receiving a lot of valuable comments on how to tackle the temp problem, I have done a lot more investigation of possible solutions. The problem lies in the BTU's injected into the uninsulated buckets, black connecting tubing, and to a lesser extent the reservoir itself.

To leave all that as is and try to cool the nutes down to 68F would take far too much energy for any practical and cost effective solution. 18,000 BTU's is simply out of reach by swamp coolers, ice bottles, mini-fridge mods, Peltier coolers, etc. And purchasing a water chiller to handle that load is far too expensive.

So my approach is to first reduce the heat load by insulating the buckets, tubing, and reservoir as much as is practical. Then I will determine, as best I can, the BTU's to bring that better insulated system down to 68F, or at least not more than 75F. That will, hopefully, give me a shot at a cooling system that is more practical and I can afford.

2) I should have tackled the hard water long ago, but wanted to see just how much of a problem it really was. While I have been able to grow a variety of veggies in it, the salts are still way too high. My choices are either try to use nutes designed for hard water (General Hydroponics has a hard water nutrient), or solve the problem more completely by getting a Reverse Osmosis system. I have decided to go the RO way, as I can benefit from the better drinking water as well as provide a known good water source for my nute system. I will need to add some calcium/magnesium additives as well as standard GD nutrients, but I believe this will be a much easier combination to work with and keep stable.

3) I knew early in the game that my 30 Gal reservoir would be undersized at some point. But, I procrastinated as I started adding more buckets, and just kept adding more water more frequently. That of course is not the best way to handle a good nute mixture. So I am now in the market for a larger reservoir that can be accessed easily for cleaning and that can be insulated. I may wind up building my own, but circumstances, availability, and high wood prices (even plywood) here in Mexico makes me look for some other way to do it. Finding stuff here is often a real challenge! Importing plastic barrels or 1-2 plastic 100 gal RV water containers from NoB are one choice I am looking at for a reasonable price. They look like they could be modified for cleaning access with a cutout.

So beyond insulating the buckets, lines, and reservoir and then throwing a lot of ice bottles at it, probably no further cooling methods beyond insulation will be attempted this summer. By next summer I should probably have a more appropriate cooling system in place as the ice bottle thing is a real PITA, LoL.


GpsFrontier 06-23-2014 12:17 AM

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Hello MontyJ,
I don't know how much new construction you have near you, or what the construction standards are in Mexico. But here in lake havasu there are new houses going up all the time. Here they wrap the whole house in Styrofoam and chicken wire before applying the stucco. If you catch them before they through out the scraps you can probably get some good size pieces of Styrofoam (as well as plywood or OSB).

I don't think you understand what I'm referring to when I say a reverse swamp cooler. Also your stuck on BTU's, and you cant compare BTU's to how it works because it simply doesn't apply. If you want to increase the cooling power of the reverse swamp cooler, you simply increase the reverse swamp cooler reservoir size (water volume). It can be as big as a small pool or spa if you wanted. You could even use your fountain as the reverse swamp cooler reservoir, and just sit your nutrient solution reservoir in the cool water.

Also the reverse swamp cooler concept only needs enough energy to run a small fan and water pump. Depending on the wattage output of your solar setup, you should easily be able to run it, as well as the other pumps and timers on solar power.

As you have already noticed, it takes a lot of electricity and time to freeze enough ice to even begin to keep up. Not to mention that everything in the freezer begins to thaw, and the ice cream is the first to melt. Or the fact you need to dump ice in the reservoir 2-3 times a day. Also keep in mind that the larger your reservoir is (and you already know it's too small) the more ice it will take to cool it down.

I know people are often confused by the term "reverse swamp cooler" I use to describe it. They tend to think of how a typical swamp cooler works, and think of it in terms of it that way. They don't really understand the the "reverse" part of the statement/concept. You don't need to go out and buy a swamp cooler (or compare BTU's). I have decided that within the next month or so I will put together a working model to explain how it works, and how to use it to cool a nutrient reservoir that I will post on my website.

Although there are literally hundreds of different ways to build one, the concept of how it works is always the same. The idea is to use the cool water coming out of it, not the air (hence the reason I call it "reverse"). I created and attached a drawing of one like I plan to build using 4 inch ADS or PVC tubing. You can also always change the configuration to include more than one cooling pad tube for more cooling pad surface area. The design's are endless, but the concept is simple, and the cost to build and run is minimal. I already have many fans and water pumps I can use, I just need some tubing and connectors, and cooling pad. If I built it from scratch buying everything I needed, I could probably build it for about $50 to $80 depending on the pump and fan I decided to go with.

Cost here in USA, and energy use (based on 9.8 cents per kilowatt hr): Electricity Cost Calculator
6 inch inline duct fan about $30 and (42 watts) 10 cents to run 24 hours
8 inch inline duct fan about $35 and (78 watts) 18 cents to run 24 hours
10 inch inline duct fan about $45 and (132 watts) 31 cents to run 24 hours
9 inch high velocity fan from walmart about $16 (96 watts) 23 cents to run 24 hours

500 gph, 8.7 foot head height fountain pump (I already have) about $40 (42 watts) 10 cents to run 24 hours

Costs per month
6 inch fan, 10 cents x30= $3.00
8 inch fan, 18 cents x30= $5.40
10 inch fan, 31 cents x30= $9.30
9 inch high velocity fan, 23 cents x30= $6.90
fountain pump 10 cents x30= $3.00

Even if I used the 8 inch inline duct fan, it would still only cost me less than $10 a month to run the reverse swamp cooler 24 hours a day all month long, and only use about 110 watts. Almost the same as a 100 watt light bulb. I'm guessing your solar system could handle that.

If I remember correctly, you said that you are renting, so I never considered geothermal energy for you because it look like the ground is brick or tile. So I didn't think you would be able to dig there. But in case it is an option I also have design plans to use geothermal energy to keep the nutrient solution cool. Thanks for reminding me though. If your interested, you will need to e-mail me so I can send you the design plans for them. I cant post a link because I don't have them uploaded to the website yet, and it will take me a couple weeks to get them posted (with everything else I need to do first). Also the forum doesn't allow attaching text or pdf. files to posts, or in private messages. So I can only send them by e-mail right now. But thanks for reminding me, I need to get them uploaded to the website ASAP. The Geothermal energy design doesn't require a secondary reservoir, and only takes the electricity of one water pump. Depending on how much you run your system, it may not even take extra water pump, or even use any extra electricity to run through it.

MontyJ 06-23-2014 01:08 PM


While I like your enthusiasm, I'm from Missouri (not really!) and it takes a 2x4 whack upside the head sometimes for me to "get past the numbers", LoL.

Example. I sent my heat transfer problem to TE Technology, those guys who make those really nice Peltier cooling plates, etc. Here is the reply I got back:

The Peltier cooler would need to remove approximately 8 kW of heat in order to cool the water from 100 F to 70 F at 100 gph in a single pass through the cooler. Peltier coolers are generally best used in applications where the heat load is less than 200 W. Your application really requires a compressor system.


Paul Lau
Engineering & Sales
TE Technology, Inc. | 1590 Keane Dr. | Traverse City, MI 49696-8257
TEL: 231-929-3966 ext. 107 | FAX: 231-929-4163 | WEB: Home TE Tech Products

Now I realize this is worse case; no insulation, realtime flow cooling, not a reservoir application, etc. But it does confirm my guess that the heat load is severe, as these numbers are "real" as far as current conditions.

I know you "know what will work" despite the numbers, but do you really believe your approach, using only 100W can withdraw 8KW of heat?

And you are right I was not clear on your "reverse swamp cooler", and still am not. But until I can get a heck of a lot more insulation on the buckets, lines and reservoir, I am not going to do anything else about the cooling.

Perhaps when I get a better insulated system and larger reservoir, I can get with you on details of your idea. I certainly am a proponent of DIY and simple solutions over complicated ones, but I also don't like to jump into projects that may be just a stab in the dark.

I did communicate with you via your website back around the first of the year and you were very helpful and quick to reply to my query, tho I have forgotten what it was about other than a drip bucket system setup issue.

You do have a ton of helpful info there and I hope people appreciate your efforts!

[Edit] I don't have any way to go with the geothermal approach, unfortunately. I am very limited on what I can do as far as the rental property is concerned. The hot patio cement area is it...


GpsFrontier 06-25-2014 10:15 PM

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Hello MontyJ,
Ya, I would agree the first thing to focus on is insulating the buckets and tubing for sure. But the second part is to cool down the inside of them, otherwise the insulation will only hold in the heat.


I know you "know what will work" despite the numbers, but do you really believe your approach, using only 100W can withdraw 8KW of heat?
I guess your not really familiar with swamp coolers. Find someone that is running one, and ask them if you can feel how cool the water in it is. I have already built two swamp coolers from scratch for my greenhouse, and the way they work is simple. The last one I ran last summer had a 40 gallon reservoir. That reservoir was nothing but a 45 gallon storage tote I got at wal-mart for about $15. It sat in full sun all day with no insulation or lid, and when the swamp cooler was running, the water temp was in the low 60's Fahrenheit, even when the daytime highs were in the 115 to 120 range.

Granted I was using a larger fan, a 20 inch fan. But that was because I was trying to cool the air inside the greenhouse (not the water), so I wanted a lot of air volume. In the case of the reverse swamp cooler, the focus is on a large "water volume" of cool water, not cooling the air. So you don't need as much airflow. Most Swamp coolers only have a small reservoir, but you can make it as large as you want (when you build it yourself). That cold water is what you'll use to cool the nutrient solution with. But even if you wanted to use the same 20 inch high velocity fan I used (like the one in the attached picture), it only uses 30 more watts (162) than the 10 inch inline duct fan.


While I like your enthusiasm, I'm from Missouri (not really!) and it takes a 2x4 whack upside the head sometimes for me to "get past the numbers", LoL.
I'm sorry, I didn't mean to whack you upside the head with a 2x4, I just wanted to let you know that BTU ratings are not all the same, and comparing apples with oranges doesn't work. Swamp cooler BTU ratings are air temp ratings, that's why they don't apply. If you want to figure BTU's you need to calculate heat exchange for water volume. It takes a lot more BTU's to cool water than it does for air. Also you can increase the BTU's of the reverse swamp cooler without using any more electricity, simply by increasing the water volume. If you want to calculate BTU's for the reverse swamp cooler, try this.

Using the last swamp cooler I built as the test subject.
First, calculate how many BTU's it takes to cool down 40 gallons of water from 110 degrees Fahrenheit to 64 degrees Fahrenheit. That's a good starting point, and how many BTU's I got for my 200 watts. Now double the water volume to 80 gallons. Now you have just doubled the BTU's using the same 200 watts.

Now take it another step. The pump I used is capable of 500 gallons per hour. To be safe because you'll most likely want to turn over the complete water volume about every 30 min, and taking into account for head height, say your turning over 200 gallons every 30 min. Using a 200 gallon reservoir, you have now increased the BTU's to five times more, using the same 200 watts. You can also easily change the amount of cooling pad surface area without using any electricity (watts), and you can also easily increase water flow with very little wattage. This is why I say don't get stuck on BTU's.

MontyJ 06-25-2014 11:01 PM

I am probably have to build me a test swamp cooler to see how it really works...being from Missouri and all, LoL.

I am not hung up on BTU's, watts, or tons. But heat exchange rates can be defined by those numbers, and bottom line this is a heat exchange issue. If you start with 100F air and 100F water and simply blow the air across the water at some rate, you claim both the air and the water get cooled down.

Where does the heat exchange come from? Just the evaporation process itself? In simplest terms, heat is being withdrawn out of the water if the water gets colder. Where is that heat going? It ain't going into the air, as the air is colder as well, right? If it is evaporation, then the nutes will be evaporating if that is the media I am trying to cool.

I've already admitted I don't know much about how swamp coolers, reverse swamp coolers, etc work, no need to swing the 2x4 in that direction again.

My plan is to insulate the buckets and reservoir as well as I can. I may move the reservoir closer to the buckets to eliminate as much connecting hose as possible and wrap them as well right up to the bucket itself.

At that point I need to calculate cooling needs. Using ice bottles, I will see what kind of heat transfers happen with the system running normally with the insulation in place. This is not an ideal way to do it, but I need to have a better handle on the insulation effects on the system, then I can start looking what it will take to keep the reservoir at some ideal temp.

One thing I noticed is that most online calculations deal only with a given volume of liquid to be cooled, and that is simply recirculated until the desired temp is reached. There is seldom any thought about every cycle, in my case one cycle per hour, injecting NEW heat into the reservoir for. That new heat load has to be handled before the next cycle starts, which is only 30 minutes. That is why I went with the worst case of asking the 'experts' how to cool the water 'real time' and that is how they (two separate resources) came up with pretty much the same ton-btu-watt requirements to do it.

With some very thick insulation on my system, hopefully the energy to keep it at 65F-70F or so will not be too overwhelming.

Again, thanks for your ideas. I learn a little more with every read!


GpsFrontier 06-26-2014 03:44 AM

Hello MontyJ,


If you start with 100F air and 100F water and simply blow the air across the water at some rate, you claim both the air and the water get cooled down.
Yes.. Heat is a form of energy, and you cant eliminate energy, it can only change form. So it stands to reason that the heat energy needs to go somewhere. But were does it go? I can't explain that at this point, and I don't claim to be a scientist. I also have a good friend that has been working in the heating and air conditioning field for over 20 years, and he services swamp coolers on a weekly basis. I have asked him where that heat energy goes, and he can't explain it either. I have thought about e-mailing that question to some university professors, but haven't done that yet. You asked me if I think it would work, and yes I do. Otherwise I never would have mentioned it, or planed to build it. I have been planing to build a working model for a couple of years. But when I had the money it was winter, and I couldn't test it. Now that it's summer again I need to make it a priority or it will be winter again soon.


If it is evaporation, then the nutes will be evaporating if that is the media I am trying to cool.
I think I have confused you. There are two separate reservoirs in the reverse swamp cooler design. One is the nutrient reservoir, the other is the reverse swamp cooler reservoir. You don't run the nutrient water through the reverse swamp cooler. That would cause problems. You can use the reverse swamp cooler water to cool the nutrient solution two ways. Either by pumping it through coils that are submerged in the nutrient solution (or vice versa) to act like a radiator. Or by placing the nutrient reservoir directly in the reverse swamp cooler water. Something like placing a smaller trash can (used as the nutrient reservoir) inside a larger trash can (used as the reverse swamp cooler reservoir). Thus cooling the nutrient solution by direct contact with the surface area of the nutrient solution container. The same way geothermal energy works by placing the reservoir in the ground (surrounding it with a cool surface that wicks away heat).

Yes, your right, the water in a swamp cooler does evaporate. That's why another term for swamp cooler is called evaporative cooler. I forget exactly, but I think it evaporated at a rate of something around one gallon of water per hour in the swamp cooler I built that I used as an example earlier. A simple float valve connected to a water line can be used to maintain a specific water level. That way you don't need to keep an eye on the water level. That's what they use in commercially built swamp coolers to make sure it never runs dry. You can get a float valve here for about $4 to $8. You also want to use a inline calcium filter (here that's about $10-$15), otherwise you will get a lot of lime scale buildup.


in my case one cycle per hour, injecting NEW heat into the reservoir for. That new heat load has to be handled before the next cycle starts, which is only 30 minutes.
That's exactly why I said that you'll need to dump ice in it multiple times daily. And that will take a lot of time, space in the freezer, as well as energy, and everything in the freezer starts to thaw. I've done it myself so I know exactly how much of a pain it is. In fact I'm doing it right now for my pepper plant. It takes about 1/2 gallon of ice twice a day for a 7 gallon reservoir.

QuietBen 03-07-2015 03:35 AM

Just found this today as I'm gearing up for growing season. Here in Albuquerque I have two problems during the summer. Heat and wind. I've implemented the "swamp cooler" approach, but didn't have my nutrient feed & return lines well insulated last year.

One trick that I've been using that I haven't seen mentioned: Instead of 5-gallon buckets with wrapped insulation, I've taken to using 5 gallon drink coolers (because they're pre-insulated.) I remove the spigot and use that as the port for my return lines.

GpsFrontier 03-07-2015 05:04 AM

9 Attachment(s)
Hello QuietBen,
Ya, they should work great if you can get them cheap enough. You would still need to make sure the water temp was cool to begin with though. If the water was warm, then the cooler wold just be holding in the heat. for me I cant get any of those second hand, and they would cost a fortune new. But I have used some small ice chests I found in the trash on trash day. They through them away because the lid wouldn't fit because the top was split and bent in. But I just used some Styrofoam I had lying around to make a lid. Cut holes in the top for the cups and used it as a small water culture system. I filled some small plastic cups with water and froze them for ice, then added a couple to it a day and the water stayed nice and cold all day, even though I had it sitting in direct sunlight all day. The plants in the pictures are tomatillo's I was starting for a friend.

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