what is the truth about adding tap to tank

[nfored]

Okay, couple things folks. The toxicity of chlorine/chloramine is proportionate to the amount of water...if you put less than 10%, the volume will dilute the chlorine into harmless concentrations. Chlorine is BAD, there's a reason they use it as a poison gas. Don't force your fish to tolerate it... I always add conditioner when I'm doing WCs, I add it to the tank right before I start filling.

RO water is terrible for freshwater tanks, and Di/RO (de-ionized) is even worse. Why? Because it has no buffer, no minerals...using pure RO in freshwater is asking for a deadly Ph crash. If you need really pure water of lower mineral content, like for rays and discus, usually you mix 50/50 with tap water.

Marine is a different story, tap water is full of nutrients and chemical crap that may cuase algae blooms and other issues. Your salt mix contains the natural elements that re-buffer the water.

My thoughts exactly

... and the level (mg/l) of chlorine/chloramine coming out of each persons tap.

Which is precisely why some people can perform large water changes sans conditioners, and others attempting the same thing would end up with a tank full of dead fish.



As far as discus, the fish below were raised in local tap water with a pH of 8.0

Stunning Period just Stunning

1:1 ratio? I don't think so, think more like 4:1 or 5:1 waste to RO.

I stand corrected I thought high end systems did much better job.