Are Nitrates Poisionous To Fish?

[andywg]

I would still say 75% is too much. Max 25% to me.

So long as the temp and pH are the same between the new water and the tank water then you can pretty much do what you want. 100% changes are not out of the question. My regular water change regime is to change 40% a time on my FW tanks.

What is the problem with adding in more new clean water? It's not like you have to acclimate the fish to lower nitrates.