Time to try a wooden aquarium
Update: still holding water! I used 2 quarts of flex seal to completely recoat the inside of the tank. My two Texas chiclid parrot fish cross were the first to test the water. These are a tough cross. Not sure if this cross even needs water. They survived so I opened the manifold. This tank has now been circulating with the main discus tank for 3 weeks. No problems. 
I’m guessing there mixed with the real parrot Cichlid and not the hybrid? At least they don’t look like balloons haha
Going with original plan. Will install a 75 gal in the space. Not sure why it separated. Uneven floor? Already repaired it twice. Time to give up. This should answer the Flexseal question though. This is the sump for my discus tank. No ill effects.
Well that sucks it happened again. Gotta be something unlevel like you said, but your main tank above it is all level isn't it? You'd think if the floor was unlevel enough to do that to the sump then it would show in the main tank too but you main tank is fine isn't it? Seems weird.
