Never use paint in a tank.
If you want to do the PVC idea, you could always use aquarium-safe silicone to affix gravel onto it though.
BV
__________________ "The more it eats, the more it excretes."  75 gal. - 10" tiger oscar 75 gal. - turtle setup (Midland Painted) + fish/crayfish (planned for the new year) |