Filtration is still unworked on - I've been very busy, and I don't have any spare cash right now to buy the pumps I want to use so it is what it is.
Several more feeders died from unknown causes. They were all in very bad shape all of a sudden, and I don't know why. I added a heater, turned on the filtration pump, and tossed some prime in the water, and the die-off stopped. My ammonia kit read zero, but the water smelled like ammonia so I dunno what gives. The water temp got down to 58F with no heater, but that oughtn't kill a goldfish I don't think. I also hadn't fed them in about a week, so maybe they were starving.
The important thing is they stopped dying so I'm pretty sure it's not something about the tank itself that was killing them.
As for a hood - no way. I'd like to, but it would be so massive and cumbersome I just dont' want to deal with it. My plan is to build 4 2'x4' frames from 1x4 or so and put greenhouse roofing in them, then hinge them together into 2 pairs, so I can lift up and fold back a 2x4' section of the top for maintenance or feeding. Cheap and simple and effective is the name of the game!
For lights I will probably get 3-6 CF floodlights and put them in light pots sitting on the clear top. That way I can turn them on independently, move them around, blah blah blah. They are also pretty cheap, and provide point source light and a nice ripple effect.
In other news, I have a single 250W stealth heater in there right now and it's raised the tank temperature from 58 to 65 so far after a couple of days (and it's climbing still). I find this fairly amazing since there is no lid on the tank and the garage is quite cool. It gives me some hope that 3-4 heaters will be able to maintain 75 degrees with a lid over the tank.