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Old 10-09-2011, 01:57 AM
GpsFrontier GpsFrontier is offline
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Join Date: Mar 2009
Location: Lake Havasu AZ.
Posts: 1,855

What type of greenhouse, what shape and materials?
The greenhouse itself is basically modeled after the design here: Horticultural Engineering - Rutgers University. I cant directly link to the exact page, so when you click on the link, scroll down just under the picture on that page and click on "2003-2007 High Tunnel Project." Then scroll down to the bottom of that page and click on "Pictures of High Tunnel Construction and Preparation," there are a total of 60 pictures of it's construction. That's the basic design but with a few small changes. I attached a drawing I made of what the framing of mine is planed to look like.

Mine will differ in the exact size, as well as doorway placement. Also I'm using 2 inch electrical conduit instead of the 2 inch metal fence post tubing. I may or may not have the sides roll up and down later, but either way it wont be done by a motor. I can easily roll it up and down myself. I was going to go a less expensive rout, but because the sub "T" system is smaller than intended (yet still 25% larger than recommended) I decided to go with a UV poly plastic like these UVA : Hydroponic Supplies and Greenhouse Equipment for the Professional Grower, by CropKing Inc.. It will cost me about $100 more to do it in the UAV plastic film rather than the regular 6 mil roll poly plastic sheeting. But the UAV film should lessen solar gain with it's UV rating, thus in the long run I think it would be worth the extra money.

How soon before you can test water or nutrient temp in the sunken reservoir?
It won't be until next summer that I can really tell exactly how well the in ground reservoirs are doing at keeping the nutrient solution cool. The average daytime temp now is in the 80's, and our summer time temps get into the 120's. So any testing now would give inadequate results. However our daytime temps were in the 100's when we were installing them, and I tested the water temp then in the first reservoir (the other two are a foot deeper). The results I got from that test was very encouraging. Keep in mind that the ground was fairly dry because we just dug a big hole, and that when I took the temp readings the reservoir was still about 80% exposed to direct sunlight all day when the daytime temps were about 105 degrees. The temp reading I got at 5 pm was 90 degrees, at 11 pm the temp was 82 degrees.

The ground temp varies somewhat from region to region, but is typically in the range of 65-75 degrees all year long once you get about 3 feet deep. Once I have everything in place, including the insulated reservoir covers painted with the reflective roof coating, as well as lined with weather striping, and the drip hose around the reservoirs set on a timer to keep the ground around them moist (necessary to wick away heat), I expect to see the reservoir temps in the low 70's all summer long.
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