When must i change water?

[Ozzlil]

I have a 30 gal biocube saltwater tank with 2 small clownfish, live rock and some soft coral. My parameters have been great, this is my third week, do I do a water change just because it is time or do I wait for the ammonia, nitrate,nitrite levels to rise before I change water?

 

[Qube]

Ammonia and nitrite levels should always be non-existent once the aquarium has cycled. Nitrate is your concern now regarding the 3. You don't want to wait for a rise in nitrates and then be reactionary, rather get in the habit of weekly water changes. I keep my nitrate as close to zero as possible by doing weekly water changes. It's up to you how much you change each week, but the recommended is between 10 and 20 percent. On my 28g I change 5 gallons weekly. Hope this helps.

 

[melosu58]

Always IMO be pro active and change it before you need to. If you wait till the ammonia goes up then your parameters will be bouncing around. Remember that dilution of excessive nutrients is only part of the PWC puzzle. Replacement of trace elements that are used up during fish and coral processes is a big part of it to. I would consider every 1-4 weeks. I do mine weekly and have for over 14+ yrs.