Long term exposure to high nitrates will do them in. Causes kidney and liver failure. The stress from trying to cope with it leaves them open to opportunistic infections.
I said a minimum for GF is 5x the turn over. That would be on lower stock count.
I keep mostly show quality imports I stock mine at 20 gallons per adult and I tack on another 10 gallons for every inch over 7inches. Filtration turns over 10x the volume of the enclosure and I also run sponge filters. Automatic water change system changes 100% of the water 2x a week
I said a minimum for GF is 5x the turn over. That would be on lower stock count.
I keep mostly show quality imports I stock mine at 20 gallons per adult and I tack on another 10 gallons for every inch over 7inches. Filtration turns over 10x the volume of the enclosure and I also run sponge filters. Automatic water change system changes 100% of the water 2x a week