1/8" lexan is pretty resistant to warping. Then LED's don't give off any heat so they should stay nice and flat. If it were T5's or something it'd be a different story most likely.
BTW just filled it with water and bringing the temp up. Found one of the two 300w heaters must be bad because it was giving off a small shock when I touched the water. Pulled it and and seeing how high I can get the temp with just the single 300w going. Most likely gonna have to replace the 2nd one though because I doubt one will get the temp past about 70

EDIT- lucked out and had another 300w heater in my spare parts bin. Back in business
