Trying another way to do water changes...
 

In terms of dilutive ratios, I know taking water out of the system then putting it back in is the best way to go, but I hate turning off my pumps, syphoning water then topping up again...

So I'm trying this setup...

I built an overflow with PVC and put it into my big pale of made water. I pump water out of my sump in one chamber and the water overflows back into another chamber. I made a little "vortex" PVC to bring the sump water into the into the bottom of the big pale... I basically sit and watch TV for 1/2 hour or till I think the new water has diluted into the tank, then dump the big pale...

I know it's a little wasteful, but it seems to be less hard on the fishes and corals as they don't even notice anything is happening...

I took a picture of the setup in mid process...
https://fbcdn-sphotos-d-a.akamaihd.n...39070786_n.jpg

I have a similar setup with two large containers and two pumps, Im sure im pumping out some the water I just pumped in, but everything seems to be happy and doesnt noticed anything is happening. Works well