nitrate

Question
the nitrate in my tank is currently at 5, i was wondering how big of a water change should i do for a 75g tank and how often can i do it? The reason why i ask is because i have corals in the tank that i don't want to loose. I have no skimmer at the moment because for some reason it just doesn't want to work, but i have coming in the mail that should be here in about 4 days.

Answer
Hi Easton,
I wouldnt do more than a 30 to 40% change. Depending on the species of corals, you can do up to 50% with some of the more hardy but it's a risky move. No species likes changes in water chemistry. However, the nitrate reduction is quite often more beneficial than the stress of frequent water changes is detrimental. And you can do it again every couple days(32 to 48 hours) pretty safely(match SG, Calcium, etc. VERY closely). Let me know if you have any more questions.