building a system 8x4 feet

[animus_divinus]

hey everyone.. im building a hydroponics system in less than a month... its going to be 8x4 feet in size, 32 square feet, about 10-11 cubic feet in total

im buying a 600w ballast kit for $100, plus a 600w bulb.. ill make the reflector myself to cover the entire table

well, id like to go with an ebb and flow system.. put a 1/2 inch PVC pipe through the bottom of the tarp-lined table, glued in to make a seal.. 8 of them, each one supplying a 4 square foot area and linked together 4+4 and then a 2 into 1... nutrients will be pumped through all of these drains and then released in a typical ebb and flow setup

what i need help determining is the grow medium... i have to fill a 96x48x4" area with grow medium for this system to work as planned, or plan a new one... frankly, this seems the least expensive route having all plants grow side by side on a table filled with the medium...

if anyone has any better ideas to set up an ebb and flow system of this size, id love to hear it

however.. gravel and sand is heavy... i think for sand or pea gravel im looking at the table holding 1,000lbs in medium alone

if i use perlite, then i have the issue of the stuff floating, though i could stretch a mesh screen over it and staple it down... the loose leaf lettuce would probably find its way through holes in the mesh? and holes could be cut to make room for the stem of other plants

ive thought about using tubes with holes cut out to fit a styrofoam plug holding the plants inside a pipe which can be flooded and released like a typical ebb and flow system.. but it would be too difficult to get this to work on smaller plants too

basically, im looking to go as simple as i can while being able to accomodate larger plants, and small herb/spice plants too

any suggestions will be helpful

[animus_divinus]

hey... i was wondering what size flour pot a tomato plant actually needs?... if not too big.. i could build my 8x4 foot table, line it with the drains for ebb and flow.. and then cover it with a thin 1/8 or 1/4 inch thick piece of plywood painted white so to not absorb light... then cut out a hole just large enough for the pot to fit in and drop it in..

then for other, smaller plants like the herbs and spices or leaf lettuce which is many, many plants per square foot i could get a 1x1 foot square pot with the holes in it, or drill them myself to grow this stuff in.. use pea gravel as a medium.. and this will significantly reduce the weight in pea gravel that i will actually need.. making this system much lighter, and even cheaper

should i do this with the pots set into a top over the entire table... what other kinds of systems could i employ with ebb and flow?... i could potentially position PVC pipe under the canopies of the larger plants or in between smaller ones to drip nutrients i bet..

i might even be able to have a solution of water under the table at all times... a passive system, i might look into those more....

if i had a system that continuously drilled solution.. i think my best bet would be to put the nutrients solution on a table above the plants.. so that gravity would feet it.. and when the upper resovoir got to a certain level (using a float as a switch).. it would turn on a pump and pump all the nutrients back up to the top.. this way the pump wouldnt run constantly.. and should there ever be a power outage i could atleast keep them fed

one question with this setup... what would be the best medium in a drip setup?.. probably something that retained water

so im liking this individual pot idea ive just thought of using.. so im wondering what you guys think would be the best system for it?

[GpsFrontier]

Hello animus_divinus,
You mention your looking to go as simple as you can, but from what I here your plans are overly complicated to me. I think it's mostly because you are trying to grow everything in one system. As I mentioned in the other forum, I would definitely use different systems for different plants for various reasons. Here is some examples of simple setups that I have built for both small as well as large plants.

Here's a simple water culture system I built for growing lettuce,
http://www.hydroponicsonline.com/for...th-system.html
A water culture system is just about the simplest systems you can build, and this one cost me all of about $20-$25 to build. It's easily expandable to accommodate as many plants as you want too (as long as you provide enough air bubbles). But you can use a lot of different materials to build a slimier water culture system setup.

Here is a simple drip system that I built for growing large plants,
http://www.hydroponicsonline.com/for...w-systems.html
A drip system is the second easiest type of system you can build, and I simply wouldn't grow tomato's with anything less than 5 gallons of root space. This system only cost about $80 to build, and that includes everything (even the pump and growing medium). It is also easily expandable to accommodate many more plants even with the same pump, although I would use a larger reservoir.

Here is another simple drip system that I built as a makeshift system to hold some Mellon plants
until I was able to build their permanent home, but I didn't have the money to build it in time before they got to big to transplant. It would have cost about $150 complete with two 6 foot troughs and growing medium, a "A" frame trellis for the vines to grow on, and an in ground reservoir and pump to keep the nutrients cool.
http://www.hydroponicsonline.com/for...26-melons.html
I built this make shift system with all left over parts, but you could easily build the same thing with new parts for about $50 including a pump reservoir anf growing medium. You could also easily expand it to more than one growing container using the same pump for multiple growing containers. I use nothing more than regular tubing that I poke holes in with a hot paperclip to make the drip holes with. Not much simpler or cheaper than that. And you don't need to worry about clogged dippers or spraying heads.

Here is a drip system I built for growing root veggies using sand and perlits similar to what you want to use.
http://www.hydroponicsonline.com/for...en-onions.html
No mater what you use as a growing medium you will run into a problem if you want to use this type of a system to everything at once in. One of the biggest issues id harvesting the plants like lettuce that don't take long to grow. As much as you try you wont be able to get the entire root system out, and the roots will intertwine with the other plants, making pulling them up much harder also. But the roots that break off and are left in the growing medium will die and begin to decay. These decaying roots will feed pathogens and fungi that can cause root rot, and plant diseases for the plants left in the system. This type of thing is what I am referring to when I mentioned plant and system maintenance being much more difficult when you try to grow everything in the same system.

Here is another simple flood and drain system I built for growing medium sized plants, but can be used for smaller plants as well.
http://www.hydroponicsonline.com/for...rd-system.html
Again this system was inexpensive and yet easily expandable, even using the same pump. I would just increase the size of the reservoir depending on the type of plants used if growing in more than one tube. The larger the plants the more water they will drink up daily.

I prefer to use coco chips for a growing medium most of the time. It retains water real well, and is fairly inexpensive running about $10 for 2 cubic feet (assuming you don't need to have it shipped to you). That also makes it about half the price of perlite or vermiculite I can get locally that runs about $20 for a 2 cubic foot bag. As I do with my drip systems I like to use rock on the bottom of the growing chamber for weight, and to aid in good drainage. That also takes up space so I don't need as much growing medium.

P.S.
Anytime you use wood in an area where it will be subject to getting wet, you run the risk of mold and rot. So if you do so make sure it's completely 100% waterproof. Also from reading the posts in both forums, I think your underestimating the size of the plants. That will cause problems for you. But we all learn from experience, and that experience just helps us in the future.

[animus_divinus]

given the size im working with.. ebb and flow might be too expensive to set up... so what i think ill do is cover my 4x8 foot table with a piece of plywood, cut holes in that to fix the net/basket pots so the roots will hang out into the solution, and run an aquarium air pump possibly through a length of PVC pipe with tiny pin holes drilled in it to aerate it all

what i like about this system, is that if i grow anything where the roots perhaps arent long enough to reach the water source.. like some herbs and spices, i could go with a wick method to supply water to the smaller plants, which will allow me to use two systems in one without complicating anything at all

so, 8x4 feet, maybe 6 inches deep, lined with a tarp and sealed in.. in the bottom will be the PVC tube with holes in it to supply air from an aquarium tank made for a 75 gallon aquarium... and the top piece of plywood will have holes cut in it to set the net/basket type pot... and really, thats all there would be to it... except the light of course

many of these deep water culture systems i see dont even have a medium for the plants.. which is fine.. and for those few plants that may not be large enough... i can plant them in some perlite mixed with coconut husk fibers to absorb the nutrients from the wick

so far (for the size im working with)... this sounds like the least expensive and simplest way to build a compact system

[GpsFrontier]

Well you can try it, but I can see a few problem. First is one 75 gallon aquarium air pump wont be anywhere near enough air for the amount of plants your planing. Especially for the large ones like tomatoes. You'll want a high volume air pump, something like this: Super Luft Pump - 3.9 psi - 66W (Output 2.3 CUBIC FEET PER MINUTE). Second a PVC tube with holes drilled in it wont be able to create all the tiny air bubbles needed like an air defuser (air stone) can, I've already tried it. Bottom line you'll want the air bubbles to be as small as they can be in order to create as much surface area between the air bubbles and the water. That's what allows the oxygen molecules to be absorbed by the water. That also allows them to be distributed thought the water and through the plants roots much better. You might try soaker hose (like for drip irrigation), it's my understanding it works well for a air stone replacement. Providing the tiny bubbles, it's also flexible so you can cover the bottom fairly inexpensively. I haven't tried it yet, but I'm told it dosen't clog like the the regular flexible air stones do.

Next is the weight. You said you didn't want your table to weigh 1000 pounds. A 8 foot long by 4 foot wide table that is 6 inches deep in water will be heavier than 1000 pounds. That will be 16 cubic feet of water. There are 7.48 gallons of water in a cubic foot. 7.48x16= 119.68 total gallons. A gallon of water weighs approximately 10 pounds. That means your table 6 inches deep full of water will weigh about 1200 pounds (without the plants). it can be done, but make sure the base is very sturdy.

Next problem is the top section you plan to place the plants in. I don't know how you plan to construct it, but there are a few design issues you will want to think about for maintenance. First You'll want to make it in sections instead of one piece. If not you will have an extremely hard time taking plants out and replacing them. The roots will also become intertwined with other plants, and cause you problems when it comes time to move them around. Also if you made it one piece you will never be able to lift it with the weight of the plants in it, even if you could or had people help you, it would collapses under the weight of the plants (when growing large plants like tomatoes, beans, peas, peppers and herbs etc.). Witch leads me to the next point, you will want to create a support system for the top spanning across the water to support the plants weight as they grow heavier daily.

Another maintenance issue is nutrient changes. You will want to at least build into your table top water culture system a "draining system." Otherwise nutrient changes will be too difficult to do. But you should really have a table to place the plants on so you can clean the water tray as well, if not you wont be able to clean it if there is a problem without killing your plants.

But if it were me and I was going with a large water culture system like that I would also use a secondary reservoir (with at least one third the water volume of the system). Pump it up through the system, and have it overflow back down to the secondary reservoir. Not only would that provide better water circulation, but make nutrient changes much easier. Instead of completely changing it, I would just empty the secondary reservoir, clean it and fill it with fresh nutrients, and only clean the main system if/when it needs it. Then let the fresh nutrients cycle through the main system. Basically that would replace 1/3 of the volume of water with fresh nutrients each time, and I wouldn't need to worry about the water level in the main system either, and/or how to add replacement water that the plants drink up (simply add that to the secondary reservoir).

[animus_divinus]

hmm.. youre math is a little wronga gallon of water weighs roughly 8.34lbs, and the entire container would be 6 inches deep but if it was filled all the way to the top, it wouldnt leave much room for good aeration, so even if it was filled up to the 6 inch point, it would not weigh anywhere near the 1400lbs of gravel, and the 8x4 by 4 inch area will only weigh roughly 600lbs...

also, i intent to have a bit of a hatch on top where i can find some free space.. atleast large enough to fit my arm in

the plants would be setting in the holes, the lip of the pot would rest on the top surface while the rest of the pot sits in.. so they could me lifted out from the top...

i could put a 1/2" piece of PVC into the bottom, and plug it with a rubber stopper like in the back of a toilet.. so all i would need to do is pull that out from the hatch to drain it into buckets below...

a question for people that have built such large deep water culture systems... about how long does it take before the solution has to be changed?

since this will be set up in a basement, im thinking of installing a float inside the resovoir, that when it drops below a certain point it will light up an LED which will be wired upstairs, maybe in my living room so that i wont miss a refill

[animus_divinus]

see, the trouble im having is when i look at other peoples systems, theyre usually small scale for single, or a small group of plants, none of them really seem to be tailored for this size.. and i will be confined to a 32 square foot area to do this with.. so putting in multiple systems would just take up additional space

instead of scaling up techniques for smaller scale hydroponics, i may want to scale down some industrial methods for this.

the table i will build will have four, maybe 6 4x4 legs, the bottom section will be 3/4" plywood and will have a border of 2x10s or 2x12s that will by fixed below the 3/4" plywood table, and extend 6-8 inches above the table to act as the dies as well

inside this a plastic tarp will line the bottom and sides, and then a rubber strip will be glued around the top of the walls so itll act as a gasket when the top piece (probably 1/2 plywood) is layed on top

ive seen drilled PVC used for large scale aeration before, works quite well...

if anyone things something other than deep water culture would be better for the project, let me know