How much water to change for SPS tank?

[ps2cho]

So I have about 70g total water between my 60DT and 20L sump.

 

Should I be doing 5g weekly or 10g weekly or maybe 15g biweekly? I want to hover around 1 ppm nitrate.

 

I was doing weekly 10g before and I think the water was too clean nitrates were 0 so I backed it off to 15g biweekly but I now am reading that 20% change at once might be a lot for SPS. No they won't die...but to maximize growth.

 

5g weekly would save me time but is 30% monthly with that schedule enough to remove all waste?

[seabass]

Sounds like 10 gallons once a week was basically working for you (but with nitrate levels lower than you'd like). I wouldn't change the frequency, just the volume of water changed. I'd try 7 gallons (10%) weekly for awhile, and see if that works better for you. You can always adjust it up or down until you get it locked in the way you want it.