Hi. i recently managed to maintain my 50 gallon cp grow tank at 76F at day and at night. i also got my tank to a stable 70% humidity at night and 70%-60% humidity in the morning. the problem is that i want to keep more of the demanding neps, which may require a temperature drop and higher humidity. im thinking of some options:

heres what i want to do im going to buy:
one of those 12v coolers for cheap
several feet of aquarium air pump tubing
water pumps for lizerds

ok, bear with me. im going to connect one end of the pump to my nep water tray, perferably with a screen to filter out all the dirt that may get into it. the other end is going to be connected to the tubeing. the tubeing would then be led into the cooler and stuffed inside. the end of the tubeing will lead back to the water tray. im hopeing that a powerful pump would be able to pump water through a long tube so that the liquids can remain in contact with the air inside the cooler for a longer periode of time. as the water swerves around the tubeing inside the cooler, it slowly gets cold and is then released back into the tray to cool the soil of the neps.

has anyone ever tried this and would this work?

i currently have a setup of a pvc pipe, a evaporative humidifyer and a ultrasonic mister. the evaperative humidifyer has a fan which blows the cool air at about 45% humidity into the tank. here, the air flow intersects with the ultrasonic humidifyer and the fog dominates the tank, raising the humidity to 70%. im thinking of getting the humidity up to 80-90%, so i need a little help. heres my options:

1) cover the tank with a glass cover. this would probably reduce the amount of light. im currently using 6 15-watt flourescent grow tubes, and they are placed rather far from my plants.

2)get one of those petflytrap evaporative humidifyers and see if it will bump it to the 80's

3)expensive, but to buy more of those evaporative humidifyers

4)load the tank with air stones and pumps (i have plenty of spare air pumps)

can anyone help me decide on my humidity prob and conferm my cooling idea? im very limited on cash right now and can only rely mostly on what my parents allow me to purcase, so no wonder machines for me. thanks. Zongyi