Quick water change question

[navychief]

When doing a 20% water change, is it best to remove 20% of the water all at once or replace the water as you remove it?

 

[Freed]

Remove then replace.

 

[Randy Holmes-Farley]

Depends on what you mean by best. I do water changes automatically with a dual head pump that slowly adds and removes water at the same time (to different parts of the system). This is certainly the easiest and least stressful way to do water changes. It is a tiny tad less efficient than doing remove then refill changes. I change about 1% daily.

I compare the methods here:

Water Changes in Reef Aquaria
http://reefkeeping.com/issues/2005-10/rhf/index.php

 

[navychief]

<a href=showthread.php?s=&postid=11639028#post11639028 target=_blank>Originally posted</a> by Randy Holmes-Farley
Depends on what you mean by best. I do water changes automatically with a dual head pump that slowly adds and removes water at the same time (to different parts of the system). This is certainly the easiest and least stressful way to do water changes. It is a tiny tad less efficient than doing remove then refill changes. I change about 1% daily.

I compare the methods here:

Water Changes in Reef Aquaria
http://reefkeeping.com/issues/2005-10/rhf/index.php

Thanks. I'll give it a read.

 

[PJsStuff]

i would think removing it all then replacing it would be best. If you remove and replace at the same time you might be removing the new stuff.

 

[Randy Holmes-Farley]

While that is certainly true, the difference is surprisingly small, and IMO, not worth the stress. With perfect mixing during the change, twenty 1% changes is exactly equivalent to one 18.2% change. With less than perfect mixing, like adding to the sump downstream from where you are removing it, the value is even higher