The whole thing is a scare tactic. Oxygen is more toxic than PVC. Gonna stop breathing? The crackpots that are trying to scare us about PVC claim that even though the chemicals that leach out are in concentrations too small to measure, they are causing huge amounts of unrecognized damage. Sounds like th boogey man to me.

I've used it for years. Hundreds of generations of tilapia and no issues.