Water Changes: What "percentage" makes it worth doing?

[darwindiaz]

Hmmm. Interesting topic. I've always been doing anywhere from 20% - 30% water change. And, Every time after I notice a dinoflagellate bloom for a week or so. Maybe I'll try doing a 15% water change.

 

[Siberwulf]

Working within the triton method, I'm hoping to not have to do water changes...or at least only for major issues

 

[workhz]

15% every couple of weeks. Will slow that down as the tank matures but may need to augment with supplements as I get more corals or the smaller ones grow.

 

[Quietman]

I used to do 2L a day for my 170L for several months. That's about 1.2% a day which equals 30% a month. I stopped after a vacation a couple months ago and so far haven't started it up again.

Now was it doing anything? I don't know. I never had any issues to correct through dilution. Didn't do jack squat for my dino problems (maybe worse). My nutrients are always low and my ICP test after stopping for a couple months didn't show anything at all. Could a WC be fixing things I'm not seeing in testing? Of course. Is it really though?

Does it sound like a good idea to do 25% a month? Sure. Does it hurt? No. Am I going to start it up again? Depends how tank does and how this new ATS I just put in works out, especially since I removed skimmer. Is it my go to if I have any problems? Yup!

Does this help anyone? Doubt it. Can you read anything you want to in here? Uh-huh - just like any discussion on water changes. Did I over use the question and response format - likely.

 

[UkiahTheTurtle]

All water changes are worth it

 

[Jbell370]

I change 5g per day, about 2% against the approx 240g water volume.

 

[Spicy Reef]

Any amount is "worth it". Please refine the question, give us more to go on. I think this is a good topic.

 

[Calm Blue Ocean]

I normally do 10% a week but lately it hasn't seemed to be enough. I think if everything is chugging along in a "normal" fashion, 10% is great, but when problems arise it's going to take more. I believe the saying goes something along the lines of 10% leaves 90% of the problem. For my tank it will be 30% changes until I can get a PO4 reading on my Hanna checker without having to dilute the sample.

 

[Turkey head]

I do almost 20% weekly in my reef tank. My non-coral tank gets a 20% every 2 or 3 weeks. I’m debating 20% every two weeks in my reef tank because is may be too clean for my LPS dominant tank. They seem to like some food in the water

 

[Tracy in Tampa]

If you do not have any issues and you dose regularly, in my experience, water changes are not only a waste of time but also makes it very difficult to stabilize your water perimeters.

 

[R33fDaddy]

Gradually working my way Towards doing no water changes at all. When my tang Gang grows up they'll need a much larger tank, so I'm trying to perfect the "no water" now.

Currently I'm down to 10% Water changes weekly. I test Nitrates and Nitrites daily.

 

[99gtbaby]

I do at least 10-15% a week and a bigger 30-40% change once a month, but my tank is also a freshly cycled immature tank, as it matures I’m hoping to cut it back to once a month to once every 3 months, and eventually a no change tank is the end goal.

 

[jgvergo]

It really depends on a number of factors, but frequency of change is critically important. If you do it daily, the necessary percentage is going to be much lower than if you do it weekly or monthly.

 

[ultraArcite]

I do 17% once a month, I can only store 45 gallons of saltwater and my tank is 180 gallons of total volume. I should probably do the full 45 gallons instead of 30 and do it more often, but it's been working so far... why fix what isn't broken?

 

[Murphs_reef]

About 10% every 2 weeks seems to keep me good. Anything more and phosphate drops too low

 

[LPS Bum]

I perform weekly 5% water change in my reef aquarium. Not to dilute nitrates or phosphates, or even really to balance water chemistry, but rather to "get under the hood" of my aquarium.

These small water changes allow me to siphon detritus that has settled on my sand bed and rock structure, to bring in some fresh trace elements for the corals on a regular basis (without having to dose for every single minor element) and to keep the tank looking healthy and clean. It also gives me a chance to clean the skimmer, replace the carbon, etc.

I have a 75 gal reef and I've got it pretty dialed in by this point. Only takes me 20 min start to finish. The fish and corals seem to like it.

 

[Twigg]

10-15% a week on all my systems.

 

[McPuff]

I generally only do water changes to remove sediment from the sump or vacuum the sand. So even though I'm taking out relatively little water (5-10%), it's the dirtiest water.

 

[DistillingDoug]

I feel 10 - 20% a week is sufficient if your tank is established and you're not battling an issue. Here's a follow up question. If you're doing an automatic change where x amount is taken out per day and replenished, how are you taking care of your sand bed?

 

[beaslbob]

Consider the following
1) something is changing at a rate of 'daily change' (say 1ppm/day increase)
2) you change out a fraction 'fraction changes' every so many days 'days' (say 1/5 every 7 days)
3) the replacement water has 'replacement water' in that . (say 30ppm)

What is the value of that just before water changes 'windup' after lotsa water changes. In effect the amount before water changes are so constant you measure the same amount.

Ans: windup=(replacement water)+(daily change)*days/(fraction changes)

For instance, say your increasing at 1ppm/day. and doing 1/5 water changes every 7 days with 30ppm water.

The system winds up at (30ppm)+(1ppm/day)*7days/(1/5)=30ppm+1/(1/5)=30ppm+(7ppm)*5=65ppm.

(hopefully i got the math correct. LOL.)

What happens is we at looking at the future end point where the system is heading as opposed to what effect any single water change does. At that end point the amount of the stuff removed is equal to the amount in the replacement water plus the build up between water changes.

With nitrates plant life like algae will consume those to eliminate the build up and additionally consume anything in the replacement water. As can anaerobic anoxic bacteria as well but the benefits of algae are so much greater. In other words nitrates will be unmeasurable.

With calcium/magnesium/carbonate (alk) I do have to use dosing. Two part, reactors and so on.

Sure you may need to do water changes for emergencies, But for normal operation they should not be needed. And actually can be detrimental.

Instead, what is important is to balance out the system where the changes being produced are being consumed. So the changes are zero or at least as close to zero as needed.

my 02