Water changes

[marie]

Originally Posted by PoonTang

I think it would depend on what the problem with the old water is. The key is stability. If it just a routine water change where the new water was basically the same as the old water than a 90% WC shouldnt be harmful. If it is an emergency WC than a 50% change could be fatal. Eg. what happens if your tank has a problem and get a pH spike of 9.0 and so you do an emergency WC and thus cause it to drop to 8.2 in a matter of minutes? Wont be a pretty site afterwards. The cure may be more harmful than the disease?
I think you need to know exactly what the condition of the old water is before we make large WC. Would kind of be like adding new corals and fish to our tanks with no acclimation what soever

Well I've been thinking about that theory, that corals get used to bad water conditions and giving them clean water conditions will make them react negatively but I just don't think thats true.

If you live in a smoky house and end up with emphysema and then move out into the fresh air, it's not the fresh air that kills you, Your just too late in moving out of the house. And i think it's the same with corals, sometimes they are just too far gone for a complete water change to save.

Oh and I have raised my tank ph from 8.0 to 9 in a very short time (adding kalk too quickly in a tank with no sump ), it wasn't a problem