Water change question...

[ReeferRyan]

I have recently added quite a bit of rock to my display and have several corals near the top of the water. I would like to do a water change but I am not sure how to now. I used to just drain the amount of water I was changing out of the display because everything would stay submerged but that is no longer possible. What is the best way to go about this? It is a 75g tank with a 30g (~1/2 full) sump and I am changing 20g of water.

 

[reefnetworth]

it want hurt if they are in "low tide" for a few minutes. either way the sump or display its gonna happen correct? REEF-ON!!!

 

[Travis L. Stevens]

It's perfectly fine to have your corals exposed long enough to do a water change. After all, corals are exposed for hours at a time at low tide on tidal flats. I would worry about exposing sponges to the air though.

 

[dugg]

If you can take water out of the sump at the same time you add water to the display, the fresh new water will go to the bottom while the old water goes to the overflow and to the sump to be syphoned out. In order for this to work, the new water should be 1/2 to 1 degree cooler then the tank water. As long as it's only a slight temp difference it won't hurt your corals.

 

[ReeferRyan]

Thank you all for your advice. What I actually did was siphon out water until the top of the rock was out of the water and then turned the return pump off and on to drain the sump and keep air exposure to a bare minimum. Got the 20 gallons out and no corals nor my 2 BTA's were ever exposed to air. Thanks again for the advice.

 

[captbunzo]

That is a fine technique, Ryan. However, all above are correct that it is NO PROBLEM for corals. Here is a fascinating article on the subject by the esteemed Eric Borneman.......

http://www.reefkeeping.com/issues/2005-11/eb/index.php

Also, I'd recommend doing smaller water changes more often. Perhaps 5-10 gallons twice as frequently, or so. It even works to do two 5 gallon water changes in a row to get MOST of the same benefit. I promise, the math works.