water change

hello everyone, ? i have a 75 gal long with a 20 gal sump. do you change 20% the total 95 gal or 20 % of 75 gal. what i have been doing is turning off the return pump letting it drain into my sump then draining it and my built in overflow. one more thing i just got a 2bulb t5 lamp that i was told i may be able to keep a few soft corals. what do you suggest.

I beleive that the 20% is total tank volume. But if you factor in the fact that there are rocks and sand in the tank, there will be less than 95 gallons in the tank. But the more volume you do the better for the tank.

With the 2 t5's you would be very limited in the type of corals you could keep. Moslty softies maybe some LPS that require lower lighting.

Brian

i keep forgetting about the rock, im up to about 140 lbs now any i an going to figure out how to post pics soon. thanks bj.

+1 Bj.

+2 bj

I go by the main tank size because of all the live rock. I would have no idea how many actual gallons of SW are in the main tank? I've often wondered this because of dosing different things, etc... Does anyone know how to figure this short of emptying the tank and measuring?