I'm going to put some Pool Filter Sand in. I was just testing to see if it holds water, and siprisingly it did, but the seams are pretty thin, so I will re-seal just to be safe.
Me and my dad already have a 220, and he's taking 2 oscars, 1 nicarguan, and a Channa Pulchra.. I wil sell the rest of the fish on the 220, and buy some monsters!