fintuckyfarms
I was going to mention last night that if the cubes were over watered that could be suffocating the roots. Mainly because I wasn't sure what you meant by the water level in the reservoir being fine. I'm not really sure what kind of reservoir your using for it either, although I can only assume that is referring to the tray with the
seeds in it sitting in another tray that has water in it. If those cubes are anything like roockwool cubes, they will suck up lots of water until their saturated. That basically drowns the roots suffocating them, and can be another reason some of those seeds haven't grown also.
When I over water my cubes, I don't ring them out, I'll place them on dry paper towels. When the paper towels get soaked, I place the cubes on more dry paper towels. The paper towels suck the water right out of the cubes quickly, and without damaging them at all. If I have a large amount of cubes to dry out, I'll use regular cloth hand or bath towels, and do the same thing. You want the cubes damp, but not soaked. Also I know you took off the humidity dome to lower the light, but taking the dome off will allow the damp cubes to dry out much faster. I assume that you may have compensated for that by allowing the cubes to suck up more water. But I'm guessing that lead to them becoming too saturated instead. Perhaps a shorter dome lid would help.
Ya, if the the water temp gets to high you'll have plant problems. Sticking Ice in the reservoir helps and is a good temporary solution. But if you can acquire a small fridge, and don't mind the electrical cost to run it, that should work quite well. As you mentioned using coils inside the fridge is an easy enough way to use the fridge without much modification. To make it as efficient as possible, first keep it in a place out of the sun with good air circulation. Like an air conditioner, the surrounding air temp has an effect on how cool it can get as well as how hard it works. Then I would use as many metal coils as I can, and place them inside as large of a container of water as I can fit in the fridge. Then as you know, simply
pump the
nutrient solution through the coils in the fridge, and back to the reservoir. But you may need to insulate the reservoir to keep your nice cool water from heating back up quickly.
P.S.
I have a feeling that giving you a fridge wont shut you up, you'll probably just have a lot more to talk about. But don't tell your coworker that...