Do you think it's safe to put flagstone in a goldfish tank?

Hi,

i was wondering if it's safe to put it and build it. its a 20 gallon goldfish aquarium! a few question!

is it safe for the goldfish?

will it put to much pressure on the glass? (it's about 70 pounds)

how do i clean it fist

and will it change the PH?

is it safe for goldfish????!?!?Do you think it's safe to put flagstone in a goldfish tank?
Should be fine. Just be careful with the weight. Seventy pounds is a bit too much for a twenty gallon tank, just be sure not to put any ';points'; directly on the glass which would create a pressure crack. If you're laying it flat, no problem. I'd go with small/medium pieces, around six-eight inches, and stack them mabey halfway up the tank. A few could reach the surface. Leave the front half of the tank empty. This shouldn't be too much weight. Glass is stronger than most people think. If you have bubble-eye goldfish, be sure there are no sharp edges that could burst their bubbles! Just rinse it off in warm water to remove the dust.Do you think it's safe to put flagstone in a goldfish tank?
Why on earth would you want to do that?