My first ebb and flow
My first system.
I made the video for my own historical purposes, but figured I would post it here.
Since the design came from many sites and posters, maybe someone can use it for their own design ideas as well.
The medium is silica rock.
The reservoir holds 9 gallons.
The pump is a 256GPH and the airstone is connected to a small aquarium pump.
The only problem I see at this point is the tray does not completely drain. The container is built with a recessed 1" edge around the bottom perimeter that holds about 1/8 inch nutrient that will not drain. I will monitor this to see if it becomes an issue.
It was a good project and I think it is practical. I will find out over the next few weeks!!
YouTube - Hydro Syst 17 Oct 10.AVI
Edit: Can someone explain how to display the video thumbnail instead of the link?
Thanks for the video, it was very informative. I'm not familiar with 'silica rock" I did a quick search and I didn't find the answer. Is silica rock porous or solid? I don't believe the the residual water that's left at the bottom when drained will be a problem, but rather an asset. The roots that hang down out of the baskets will dry out much faster than the ones in the growing medium. Therefore if they can get access to a water supply (depending on flooding cycles) it would be a benefit. In fact, if it were me I would want at least about an inch of water left at the bottom when drained (at least enough to submerge air stones). Also I would suggest to put the air stones (currently in the reservoir) in the growing chamber with the roots. Any roots that may be submerges for long periods of time will benefit from the direct air bubbles.
Looking forward to seeing the plants grow!!!
Last edited by GpsFrontier; 10-19-2010 at 03:26 AM.
Ah, sorry GF, I believe they contain a level of silica, but they are supeheated shale. Here is the product. They hold water like hydroton, but don't roll and supposedly over time release trace amounts of a couple minerals.
The cost was a bit cheaper than the hydro, so I went for it.
Sunleaves :: Growing Media
There is not enough room in the tray for an air stone as the water will stand at about 1/8 inch. I do like the idea of using tile squares to keep the roots from laying in the water.
My assumption is that once the roots get big enough, they will draw the remaining water from the tray between flood cycles.
I am anxious to see how the flood cycles need adjustment as the plants grow.
Hey halfway, the air-stone is a redundancy in an ebb and flow system that is setup correctly.
When you drain an Ebb and Flow system, it creates a tiny vacuum in the grow chamber that pulls ambient air into the chamber all the way to the very bottom.
Timing your drain cycle to supply the proper amount of air is the key. The drain cycle should be as often as possible within reason, both botanically and financially. Too often and it doesn't really help but will use electricity.
The timing depends on ambient conditions of course. If it's very hot out, you'll have to increase your floods to compensate for the heat and to keep the roots at the correct temps. When it's cooler, not as many floods are necessary.
Here's what makes some ebb and flow people crazy when I say it; I use a one hour on/ two hours off cycle, 24 hours a day, 365 days a year. I've done so for more than 20 years on all my plants and they simply love it.
This timing provides maximum nutrients, maximum water and maximum oxygen to the roots while keeping them cool even on 100 degree days.
During the drained cycle, the plants still have plenty of water due to the retained water within the media. This is why using a porous media like hydroton is so very important.
It takes the plant much more time to use all the oxygen that is pulled into the growing chamber each two hours. There will be plenty for all the plants needs for the entire two hours of being drained and if the proper media is used, there is plenty of water also for the herringbone roots to absorb.
Having a properly sized grow chamber is absolutely necessary for the above reasons. Too small and not enough root space, water retention or oxygen is supplied to the root zone.
You really can't go too large. The roots will expand to what they need. If you use a grow chamber that's the size of Detroit, the roots will stop long before reaching the city limits.
With all hydroponic gardening, timing, timing, timing is the most important factor in it's proper use.
Many hydroponic growers will insist that a 15 minute flood is proper. I've proven that it doesn't work as well as my one hour flood with a two hour drain cycle. That's why I've used it for all this time after trying many, many combinations.
A 15 minute flood will work. I've found it just doesn't work as well as the one hour flood for me.
I agree with most everything that NorEastFla is saying, although I have a couple of points. Yes the drain cycle does draw in fresh air with every cycle, but does not add dissolved oxygen to the water itself. And the way I see it, you just cant get to much oxygen to the roots. So I like to get it there every way I can, including using air pumps (in the water) and hydrogen peroxide. But is it necessary, no not really especially if it's not hot.
The long on/off times is largely based on the setup itself (including the growing media). For moisture retention I like using Coco chips, it holds moisture more than twice as long as the hydroton (grow rocks). I don't really have any set flood/drain times myself. I just watch the plants and growing medium, and adjust as I feel necessary. But I don't think that I have ever had luck with off times longer than 30 min. The timer I used (for the flood and drain systems) has minimum 30 min on/off times, and with 1 hour off the plants tend to wilt (especially in warm weather). In fact during hot days I often set the timer for "30 off" and "1 hr on" during the hot part of the day (especially while getting direct sunlight). In the late afternoon when they get shade, I'll set it back to 30 on/off.
But in a drip system (using coco chips and 5 gallon buckets) I have often used a 30 on and 2 to 2 and 1/2 hr off, even on hot days. In fact there has been a few of times where ether the gfi tripped or I forgot to plug the pump back in, and did not even find out until 3 or 4 pm the next day, and the plants still were not wilting. It really all depends on the setup, so I try not to give people the on/off times they should use. But rather give starting options, and stress keeping an eye on the plants for them to decide what works best for there setup.
GpsFrontier has brought up a very important factor in the timing and construction of an ebb and flow system that is outside in ambient temperatures.
Heat is a real problem. In some places cold can also be a problem.
The ideal root zone temperature is 75-78F. The roots can take up oxygen and nutrients best at that root zone temperature.
If you live in an area where the ambient temperatures can get to 90+ for extended times, its a good idea to run your flood times more frequently to keep the root zone at the optimum temperature.
You can also do other things to help. Putting the reservoir into the ground will help keep the nutrient solution cooler. This is true regardless of the type of system you use.
Installing a chiller on larger systems can be a must in some locations where its impossible to keep the reservoir temps down to a reasonable limit.
Putting a temperature probe into the root zone periodically during the drained cycle will tell you if your root zone is getting too hot. If so, increasing the flood timing will sometimes resolve that problem.
In areas where it gets cooler than 50F at night, that also can create a real problem. It too can be resolved and the growing season extended by using more frequent floods. Again, monitoring the root zone temp is the only way to tell if its getting too hot or cold.
I live in Northern Florida, and have used NFT almost exclusively outside in enclosed growing areas. I sometimes forget that most other places have to deal with larger temperature differences than I do.
fantastic info folks and I really appreciate you being so forthcoming!
The hydro systems will all be in the basement for now so I have temps from 60 to 68 pretty steadily. I actually wish I had a bigger drop at night, but no worries. It is mainly for lettuce and some spices at this point.
I'll maintain the containers and raised beds outside for now as I am really happy with the efficiency I have achieved at this point.
I do see an NFT outdoors in the future and they will sure enough resemble those I have seen posted.
My little seedlings are like watching well...seedlings grow, he he he.
Last edited by halfway; 10-20-2010 at 07:08 AM.
You might want to consider using an Aquarium heater set to 75F.
There is a remarkable difference in how much nutrients and oxygen the roots can take up when the temps are in the correct range.
60 is a little cooler than I would be comfortable with. 68 is actually marginal.
The heaters are inexpensive and run on about 100 watts.
Summers are a whole other issue, I do have a new plan of attack other than the in ground geothermal reservoir (I will still be using), that I plan to test come spring. I got the idea from someone in another forum who says it works well. I get the setup and principals of operation, I just haven't tested it myself (and wont be able to until it gets hot again).
Last edited by GpsFrontier; 10-20-2010 at 03:45 AM.
Update Nov 1, 2010
Here is an update on the system.
I believe I will not only journal the growing season, but will add the video updates as well to provide me with a clearer picture over time.
I said "roto rooters" up front, LOL. I have that stuck in my head!!!
I am going to explore rock wool and coco coir prior to reaching the next germination cycle in a few weeks.
I am anxious to see how the drain cycle does with the rooters. They tend to stay pretty moist.
YouTube - Hydro System 1 Nov 10.AVI
How to embed the vid instead of just the link???
Last edited by halfway; 11-05-2010 at 09:50 AM.
Excellent video, halfway!
It's hard to tell in the video, but is your reservoir lid transparent?
The reason I'm asking is because if light can hit your reservoir solution, you'll have hell to pay with your pH and algae growth.
Great little system you have there!
What's the combined wattage of your lights?
What's the total square footage of your grow area?
I have 3 2-socket 48 inch shop lights for a total of 6 lights. They are T8, so 32w each. All of them are 6500k for vegetative growth as I am only growing lettuce and basil at this point.
The grow area is roughly 18 inches wide by 40 inches long if I avoid the low-light end portions of the lamps. I kept the lights raised for the video, but I am actually keeping the light between 2-4 inches above the plants as I do with my starts in the Spring. Since they throw very little heat, the temp never really exceeds 72 degrees, so my lettuce should make it to full harvest before bolting. We'll see.
I'm still studying lighting solutions for peppers and tomatoes as I'm gonna need a larger area and red wavelengths to support flowing stages. I'll keep those comments and questions in the lighting thread.
This system was originally designed to fit as a single unit tray inside the reservoir), but I didn't like the method of topping off or refilling solution so I seperated it. I have room on that workspace to double the setup. I will likely do that once this first batch teaches me a few things on design and efficiency. I like the idea of having 12 full 5 inch pot capacity.
Last edited by halfway; 11-01-2010 at 07:24 PM.
Cool video, and keep them up if you can.
Even though I don't always practices what I preach, keeping logs of what you do is important to understanding the results later. I was told/taught that early on (and know it's important). But what I can say is that I'm lazy (you may not be lazy like me). I do intend to keep better records of my progress along the way (but no promises).
Day 5. The lettuce is a bit on the light side, but as another poster told me, the Simpson Elite seems to remain a lighter shade of green.
I will up the nutrients in another week. We'll see if that changes anything. The basil is so strong, the grow area smells like lemmons!
I am very impressed with the results after only 5 days. The simplicity is incredible.
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November 8th. This is the 8th day in the system and I'm impressed with the results.
I did have to get a fan on the lights as the surface temp was 82 degrees. The fan brought it down to room temp of 71. Those T8s put off a little more heat than I thought.
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Last edited by halfway; 11-08-2010 at 10:14 PM.