[GpsFrontier]

1. Smart. Your black plastic rolled over elastomeric on a frame idea is REALLY clever. How you came up with this idea, I don't know, but it's very smart. I think I will try this for levels 2 and 3 of my greenhouse.

well, I cant really take credit. Even though I knew what the elastomeric roof covering was, I never thought about using it for that. I was looking for clear plastic sheets in the painting department. When they asked me what I was looking for, I told them larger rolls than they had their. He pointed me over to the home insulation section, where they had large rolls of the clear plastic sheets. But they also had the same 6mL plastic in black as well as clear. Witch suited my needs for lining the hydroponic system with (I was also looking for). So I stumbled onto that one. Then when I asked another employee if contact cement would work for my purpose. He said it would work just fine, but be hard to apply to the rolled plastic unless you use the spray, and to get the water based contact cement, or the solvent based one would decompose the plastic. So while back looking at the contact cement I asked that employee about water based spray contact cement. He said they didn't carry any (or make it, not sure which). Then he asked what I had planed, so I explained it again. He thought about for a minute or two, and it was him that came up with using the elastomeric roof covering instead.

I was concerned about it curing correctly under a non-porous surface (the plastic). But he assured me that only one side needed to be porous, and the OSB being porous was all it needed to cure correctly. He suggested rolling on a relatively thick coat, then after laying down the plastic, to use a roller to work out any air bubbles. He also said it would take about 24 hours to cure/dry, so I would give it 48 to be sure. The cool thing is the elastomeric roof covering is waterproof, so if the black plastic ever got a cut in it, the OSB would still be protected. Moral of the story, don't be afraid to talk to or ask your friendly neighborhood hardware store employees (their my best friends).

you plan to recirculate the water which overcomes that concern; however, I wonder whether having multiple smaller recirculating systems rather than one large one might make sense (e.g., so that 1/2 strength nutrients of one pH / TDS level could be recirculated to seedlings, heavier concentrations and/or other pH level solutions could go to more mature or different varieties of plants, etc.)?

Each level of the hydroponic system I'm planning will have its own reservoir. With the 3 different levels, I will already have 3 different reservoirs. So yes the seedlings (planed to be on the bottom level) will be separate, and have a low nutrient concentration. The middle and top levels will be progressively older plants, with the oldest plants being on top. Each of those levels will have the ability to have different nutrient levels as well. Sure I could break it up even more, and have two different reservoirs for each level. But then (even though they would be smaller) I would need 6 reservoirs instead of 3, and 6 pumps instead of 3, 6 UV light systems instead of 3. And even though if I used 6 reservoirs instead of 3, and it's true that each would only need to be half the water volume size. It would still take more space to place 6 smaller reservoirs in the ground, than it will to do 3. Also Larger volumes of water take longer to heat up. Two 125 gallon reservoirs will warm up much faster than one 250 gallon one will in the same conditions.

3. Fish. I'm wondering whether it makes sense to experiment with a couple hundred gallon talapia-stocked "aquarium" (a tank lined with pondgard EPDM)? Feed the fish their fish food and let fish output feed the plants? The bonus is fish to eat and/or sell for $3.00 per pound wholesale. Do you have any thoughts about this? Do you think this might have a chance of working?

Yes, absolutely it works. There are many commercial farms that use aquaponic techniques to grow both produce, as well as fish for the market. However it's not nearly as easy as hydroponics. Aquaponics has a lot more challenges to deal with. Here is a thread I started a while back where I posted a bunch of links to infromation about aquaponics: http://www.hydroponicsonline.com/for...quaponics.html. Currently I have 14 PDF files saved on my computer about aquaponics. If your want more info I can post links to those as well.

4. Greenhouse. I'm planning to cover the inside frame walls of my greenhouse with fiberglass window screen then, on the outside, constructing a hinged frame hung from the top of the frame wall to which I'll attach Lexan corrugated fiberglass panels. These panels will be able to be swung open on hot Summer days for breezes while keeping out most larger bugs; during Winter months, just close it up and it will act like a normal greenhouse.

If I have it correctly, you plan to use the screening, completely around the inside to keep bugs out when the outside is open. And the outside walls will completely open. Basically the whole wall/s is the window. I think the corrugated panels are quite expensive. They are here, running about $15 for a 8x2 foot sheet. I might use the corrugated panels on the roof (and pitching the roof adequately for rain of coarse). But for the sides, I think I would use clear plastic instead. I would design it so it was easy to roll up and down, and the same with the screening. You wouldn't need both down at the same time, just one or the other. I attached some pictures of a greenhouse that I'm modeling my herb greenhouse after, and it has the same rolled up sides I'm talking about. When you roll up the plastic, you would roll down your screening to keep the bugs out. But keep in mind if you use screening to keep bugs out, you will be keeping bees out as well. You may have a hard time getting some plants pollinated that way.

P.S. jamromhem
Funny you should say that, I was at Wal-mart looking at it today as well.