Water Changes

[nmdelrio]

Wondering if one can overdo water changes for a mature tank, for example, 50% water changes twice a week, is this too much?

 

[Bloo]

That sounds way too much. 50% is even pushing it once a week. Why do you want to ? Is it extremely overstocked ?

 

[teaker1s]

I would suggest 20% several times a week that way you don't drastically alter tank conditions suddenly-less water removed at a time means less stress for fish

 

[annka5]

Why do you need to do so many water changes? If left to me, I'd aim to keep nitrates at a sensible level - say 10ppm of the tap water, but set a minimum of 20% per week water changes even if not required to keep nitrates at that level.
I agree with Teaker re: 50% changes. Another option is to siphon substrate and rinse filter sponges in resulting tank water, which helps keep nitrate low, if that's the reason for the water change regime.
It does depend on the fish as well -if you're raising discus, for example, then 50% twise a week is not too much at all, though IMO 20% or more daily would be better option.