Water Changes: Why do you do them

[reefnewbie83177]

OK, So the title sounds a bit lame, but I am curious about the reasoning to water change. I would guess that the biggest reason to do water changes is to reduce nitrates/phosphates/or other contaminants that you do not want in your water, so by remove a certain percentage of water you are effectively reducing these unwanted contaminants. The other reason that I see is to add back in essential nutrients that get stripped by coral.

Anyway, the reason I am interested in this is b/c I have now gone almost 2 months without a water change. I feel like I have a very effective system set up with my 90 gallon (oversized skimmer, live rock, good bacteria base, and a solid refugium). I have a mostly SPS reef system with a few LPS. I dose my own ALk/Ca and they are always 9.5/475. Everything in the tank looks great and is growing just fine. I check my nitrates and phosphates at least once a week and they are always zero. Of course I now they aren't really zero, but I have no algae problems in my DT, and in my refugium I am growing Mangrove and Chaeto to help sequester nitrates and phosphates.

Anyway, my question is: For those of you who have SPS dominant tanks and don't do weekly water changes, do you dose other additives than your basic calcium/carbonate? Do you replace trace chemicals with additives? Or does everyone do weekly water changes.

Thanks in advance

 

[jerpa]

I don't view water changes as being an effective means of nutrient export when compared to GFO, carbon dosing, and macro algae. They do help but my motivation for water changes is more for trace element replenishment and the hope that anything harmful that may buildup will be diluted. I don't do weekly water changes although I always end up using my system water for fragging, brine shrimp, quarantine tank changes and the like so I'm constantly adding new water. I also rinse my carbon and GFO by running system water through it and down the drain. Then occasionally I do a ~30 gallon change on its own every month or so.

 

[bertoni]

This article covers why water changes can help:

http://reefkeeping.com/issues/2005-10/rhf/index.php

Restoring the ionic balance is one important purpose. Removing any organics that build up can be useful, too.

 

[Ron Reefman]

reefnewbie,
I have a 350g system (180g DT mixed reef of sps and lps, a 75g anemone tank and a 120g sump,refugium, DSB). It's been set up for 2 years now and I change about 25g/month. I don't dose trace elements and like you, I have a great skimmer, lots of LR, good flow, a 30g fuge, a seperate 30g DSB and a diy coil denitrator. I have no algae issues (other than the macro algae in the fuge doesn't grow much... I assume no food), zero nitrates and usually zero phosphates. Oh, and the corals that were very small 2 years ago are now growing into each other.

 

[tmz]

I do 1% daily water changes plus extra changes related to maintenance totaling about 40% per month for consistency in ionic balance as well as minor and trace elements.

 

[spinsonic]

I recently ask this same question. I too have had zero issues with ammonia, nitrite and nitrate. keeping phosphates down with gfo reactor between .04-.10. daily dosing of b-ionic two part to keep ca, alk, and mag levels up.