View Full Version : Specific Water Change Question

09/01/2017, 08:33 PM
So, a year ago I added cheato to my sump and a 200 watt grow. My nitrate went to trace shortly there after and the cheato filled a 8x8x8 space, full every two weeks or so. This was with minimal water changes and dosing supplements.

So the last three months or so, I built a new water mixing station in the garge and have switched to 50 to 60% changes once a month. Feeling that my previous routine was perhaps resulting in 'stale' water and changes would be best.

So now, my nitrate is still trace, however, my cheato growth is almost zero, there is a little bit, that is just becuase I am over feeding to get it to grow.

Could my water be too clean now? I liked having the cheato growth and see little effort in chnging a measly 10 percent.

Should I embrace the slow cheato and keep up the 50 percent changes or go back to running older water longer, does saltwater in an active closed system go stale? Thanks. I look forward to all thoughts on this.

09/01/2017, 08:46 PM
10-20% a month seems like a reasonable rate to me. I wouldn't do 50% changes except in emergencies, but if you do them regularly, the tank should be fine with them. This article discusses water changes in detail:


I don't think "stale" is a good term to use for water. The tank might have a buildup of certain elements or organics, or it might be come depleted of some elements, or both. Water changes can fix those issues.

09/02/2017, 08:30 AM
Large water changes like 50% can also throw off element balances . Water,H2O, doesn't go "stale ".

09/02/2017, 04:45 PM
When possible I always choose the water change and I have no problem with 50%. My corals love it.

09/02/2017, 05:19 PM
I would go with the lower % water changes. I added a algae scrubber to my sump and took out my skimmer after the pump went out. It's been six months and I do half the water changes I used to and my corals look great!

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09/02/2017, 08:12 PM
Thanks everyone. I see no negative results from the largr changes and with the nice setup I made I actually enjoy doing the changes. Only a couple of valves to flip.

The other thing I have done and liked was continious, daily dosing pump water changes. Thamks everyone, good points all, more to think about.

09/03/2017, 05:46 PM
Algae, phytoplankton and bacteria compete for similar nutrients. Large water changes have been shown to greatly disturb bacterial populations (I think this was a Shedd aquarium study). In your case, a large water change might have allowed a particularly aggressive species or multiple species of bacteria to dominate nitrogen consumption and starve the Chaeto. For the aquarium water chemistry, no net change, but a detriment to the macro alga.

With regard to the notion of stale water, maybe think of water that is never changed as a microbiome that evolves over time in the number and types of bacteria, in a manner we know little about at this time. And maybe water changes of the right size and frequency act like bacteria population resets, where generally good or at least harmless changes to the microbiome occur. Understanding the aquarium microbiome might be the next big thing in aquarium management.