how much water change

[area]

I just started 130g system with 65g sump. My question is how much water change is enough ? thanks for your help.

[bertoni]

I try to do at least 20% once a month, preferably 20% twice a month. I don't know of any real data on what the minimum should be, but it'd vary a lot, depending on how the tank is maintained.

[drummereef]

I do at least 10% weekly. Smaller, more frequent water changes yeild positive results imo. A little more definitely won't hurt.

[demonsp]

If all readings good and no problems then 10% weekly changes on a regular basis is the best you can do. Be sure your toped off as not to change salinity level. Sometimes if reading high or other problems its good to do bigger then 10 % but depends on case i guess. GL