Are water changes over rated?

[saltyMJ]

I've had a 30 gallon reef tank setup with all soft corals and 5 fish for almost 2 years. I think the best advice I got over this time was to stop doing routine water changes. The first year of my tanks life I was on a weekly water change schedule and was constantly battling fluctuations with readings and corals being happy and then unhappy. Then I stopped doing water changes, and my tank has flourished over the past year! Haven't done one in months and i just took readings. Nitrates are at 0 and the corals and fish couldn't be happier! So are water changes over rated? What do you think?

 

[liddojunior]

Well depends on the corals and if you are dosing.

I have a softie only tank that can get away with me adding just trace elements. And only doing small water changes like bimonthly.

But my LPS tank requires frequent changes and keeping up with dosing. LPS and SPS corals soak up the alk, CA, Mg. And it’s easier to do water changes than rely only on dosing. I feel like there’s some trace things that build up or are lost that just needs some new water to be mixed in the system.

 

[saltyMJ]

Well depends on the corals and if you are dosing.

I have a softie only tank that can get away with me adding just trace elements. And only doing small water changes like bimonthly.

But my LPS tank requires frequent changes and keeping up with dosing. LPS and SPS corals soak up the alk, CA, Mg. And it’s easier to do water changes than rely only on dosing. I feel like there’s some trace things that build up or are lost that just needs some new water to be mixed in the system.

Yeah I did forget to say that I started dosing when I stopped water changes. Reef fusion 1 & 2 once a week and magnesium once a week and the levels stay stable. Took a few times to get the amounts right but once you do it's way easier than weekly water changes in my opinion.

 

[Dragen Fiend]

Only time I WC is if something needs immediate attention or I have an algae bloom and need to lower nutrients faster.

Otherwise I monitor parameters and dose accordingly.

 

[JNalley]

I might be in the minority, but I am of the opinion that everyone should be actively pursuing the goal of no water changes. At the beginning, it's sort of mandatory as a Nutrient Export mechanism, as well as a way to replace some trace element loss (more on this below)... But as your tank matures, and your ecosystem adapts, they become less and less necessary. I typically stop water changes on new tanks (from a dry rock start) after about 6-12 months, depending on how stable things are. From a Live Rock start, I find that can be moved down to 3-6 months or less sometimes.

The "trace" element replenishment argument is one I hear about often, but you have to wonder how a 10% water change is bringing those elements back up to levels that they need. Let's take Calcium (Not really a "trace" element) because it's easy. Let's say your salt mix is 450ppm Calcium. Your tank is 100 gallons total water volume, and your tank is consuming 50ppm Calcium a week. So you get to your first water change, your tank is down to 400ppm calcium, you remove 10 gallons of water (the water is still 400ppm calcium) and you add in 10 gallons of freshly mixed water which is at 450ppm calcium. You only increased the total calcium in the tank from 400ppm to 405ppm Calcium. Next week, you're down to 355ppm Calcium because of the 50ppm weekly consumption, and you change 10% of the water again, bringing it up only to 360ppm calcium... This is why trace element replenishment is sort of a bad argument. You're always going to need to dose if something is consuming, unless you're doing 100% water changes to account for the loss.

 

[malacoda]

There is waayyyy too much diversity and variability from one tank to the next to get a resolute answer to ... or try to come to a consensus on ... a question like, "Are water changes overrated?"

I'd even go so far as to say there is way too much variability and progression in a tank to come to the conclusion that specific tank will never benefit from regular water changes again at some point in the future.

Life in our tanks is complex and always changing. What works well today may signficantly change next month ... or next year.

I've seen tanks became more stable when regular water changes were stopped.

I also know of tanks that did great without regular water changes ... only to suddenly go downhill literally overnight and be resuscitated by beginning a regimen of steady, regular water changes.

A lower nutrient ... or even ULN ... SPS tank with a light bio-load may likely be a little less stressed, and do better, with careful dosing and no water changes.

A higher nutrient SPS tank ... or heavily fed LPS tank ... could have a much higher likelihood of suffering a nutrient spike or crash without them.

It all depends on the current state and balance of your tank ... as well as your specific filtration, dosing, and other maintenance steps you take.

In short, IMO, no, they are not overrated. Sometimes they may not be needed, other times they may be key part of success.

It all depends on the tank. How it is maintained. And its balance/need at a given point in time.

 

[York1]

No

 

[ca1ore]

Water changes are NOT overrated, whatever that actually means; but they may be unnecessary under certain circumstances.

When I deleted my 450 gallon SPS tank from my system, retaining only the 120 gallon softie/LPS tank, I kept much of the support equipment the same. So the 90 gallon per month AWS that was a 15% monthly change before is now a 60% monthly change. Softies and LPS have never looked better. Even my blue ridge coral has polyps now.

No matter how clever you think you are or your filtration is, stuff builds up over time.

 

[KandAReefs]

I would not say no water changes is the goal but I do them as needed. If the tank needs it every week I do it if not 2 or 3 weeks or more but to not change out any of the water I don't see as a great idea.

 

[Uncle99]

When I do the small water changes, tank stays clean.
When I stop over a few months, it gets dirty, especially pumps.

 

[fish farmer]

There is waayyyy too much diversity and variability from one tank to the next to get a resolute answer to ... or try to come to a consensus on ... a question like, "Are water changes overrated?"

I'd even go so far as to say there is way too much variability and progression in a tank to come to the conclusion that specific tank will never benefit from regular water changes again at some point in the future.

Life in our tanks is complex and always changing. What works well today may signficantly change next month ... or next year.

I've seen tanks became more stable when regular water changes were stopped.

I also know of tanks that did great without regular water changes ... only to suddenly go downhill literally overnight and be resuscitated by beginning a regimen of steady, regular water changes.

A lower nutrient ... or even ULN ... SPS tank with a light bio-load may likely be a little less stressed, and do better, with careful dosing and no water changes.

A higher nutrient SPS tank ... or heavily fed LPS tank ... could have a much higher likelihood of suffering a nutrient spike or crash without them.

It all depends on the current state and balance of your tank ... as well as your specific filtration, dosing, and other maintenance steps you take.

In short, IMO, no, they are not overrated. Sometimes they may not be needed, other times they may be key part of success.

It all depends on the tank. How it is maintained. And its balance/need at a given point in time.

This.

My 14 year old 29 gallon sumped tank needs regular twice monthly water changes. I'm not just changing water, I'm also sucking out detritus, occasional algae, loose mushrooms, etc.

I actually got to a point around 2020 -2022 when algae was under control, chaeto wasn't growing in the fudge, N and P were barely detectable, corals growing well. I even started feeding much more. I started to cut back on my volume of water changes.

This past year I removed a large rock, disturbing things a bit. I immediately started a cyano/GHA battle, which I feel is turning a corner, larger water changes, new chaeto, new CUC.

I know several would call for a rip clean of the tank with a 100 percent water change, but that is not how I roll. Corals generally doing well currently.

 

[Randy Holmes-Farley Verified Community Expert]

I've had a 30 gallon reef tank setup with all soft corals and 5 fish for almost 2 years. I think the best advice I got over this time was to stop doing routine water changes. The first year of my tanks life I was on a weekly water change schedule and was constantly battling fluctuations with readings and corals being happy and then unhappy.

IMO, better advice would be to do water changes in a way that did not mess with your basic parameters. That can be accomplished in at least two ways:

1. Use a salt mix matching your tank
2. Dd very frequent small water changes, such as by AWC.

 

[Subsea]

There is waayyyy too much diversity and variability from one tank to the next to get a resolute answer to ... or try to come to a consensus on ... a question like, "Are water changes overrated?"

I'd even go so far as to say there is way too much variability and progression in a tank to come to the conclusion that specific tank will never benefit from regular water changes again at some point in the future.

Life in our tanks is complex and always changing. What works well today may signficantly change next month ... or next year.

I've seen tanks became more stable when regular water changes were stopped.

I also know of tanks that did great without regular water changes ... only to suddenly go downhill literally overnight and be resuscitated by beginning a regimen of steady, regular water changes.

A lower nutrient ... or even ULN ... SPS tank with a light bio-load may likely be a little less stressed, and do better, with careful dosing and no water changes.

A higher nutrient SPS tank ... or heavily fed LPS tank ... could have a much higher likelihood of suffering a nutrient spike or crash without them.

It all depends on the current state and balance of your tank ... as well as your specific filtration, dosing, and other maintenance steps you take.

In short, IMO, no, they are not overrated. Sometimes they may not be needed, other times they may be key part of success.

It all depends on the tank. How it is maintained. And its balance/need at a given point in time.

Kudoes to this post.

“I'd even go so far as to say there is way too much variability and progression in a tank to come to the conclusion that specific tank will never benefit from regular water changes again at some point in the future“

As a Laissez Faire reefer, I don’t do regular water changes. I only monitor salinity and to compensate for evaporation, I add RO water to control salinity increase and I add trace minerals. Once a year, in a 7 day period; I do three 50% water changes to get tank parameters back to standard seawater. If I need to test water, I send it off to a regional agricultural lab.

 

[Doctorgori]

yes, overrated until your tank crashes…

TBH I’m torn: just submit to the ole “bucket brigade” OR keep adding, adjusting, tweaking my current water till it’s biologically perfect …
…did I mention I hate water changes

 

[Alexraptor]

The issue with no water change approaches is there is no way to reliably test for everything going on in our system. Not just changes in water chemistry, but build up and balance of toxins and metabolites. This can lead to situations where a tank that is seemingly fine, goes downhill very quickly.

Personally I have a tank i run without frequent water changes, but I always do a series of large ones in short succession about once a year, to eliminate any kind of buildups and reset drifting parameters.

 

[Doctorgori]

The issue with no water change approaches is there is no way to reliably test for everything going on in our system. Not just changes in water chemistry, but build up and balance of toxins and metabolites. This can lead to situations where a tank that is seemingly fine, goes downhill very quickly.

Personally I have a tank i run without frequent water changes, but I always do a series of large ones in short succession about once a year, to eliminate any kind of buildups and reset drifting parameters.

Related:

pardon to drag in celebrity but @Randy Holmes-Farley advocates (or does) frequent small H2O changes but I’ve never wrapped my head around the “digression” math problem ( for “pollution dilution” in a given volume)
…. this issue (large vs small H2O changes) has been the topic of many threads

…Just my observation but: On one hand small changes makes sense from a replenishment/ stability POV but not from a correction/dilution POV ….especially when observing the noticeable positive effects a massive 33% change has on tank inhabitants…

perhaps a mix of the two techniques….I dunno

 

[saltyMJ]

I guess over rated is the wrong phrase. I just meant that when you start a tank or first get into the hobby you hear how you have to do weekly 20% water changes to keep nitrates down and that is the only way to properly do things. Or at least that's what I read and i believed. The advice to simply "stop water changes and try dosing" was shocking to me because wouldnt all the nitrates build up? And I was even more shocked when my tank started to flourish after doing it. So after atleast 6 months of not doing a single water change, why aren't my nitrates building up? Where do they go if water changes are the only way to get rid of them and I'm not doing those? My conclusion was that weekly water changes were not necessary at all for my tank! Perhaps this is just a temporary phase my tank is going through though. I hope not cause water changes suck!

 

[VintageReefer]

Every tank I’ve managed over 24 years has no water changes in mind. My only failure was one of my first tanks that had a 6/7” dsb, and even that lasted 6+ Years

This tank was setup 8 years ago. There hasn’t been a water change in at least 4 years

 

[Randy Holmes-Farley Verified Community Expert]

…Just my observation but: On one hand small changes makes sense from a replenishment/ stability POV but not from a correction/dilution POV ….especially when observing the noticeable positive effects a massive 33% change has on tank inhabitants…

The dilution with small changes comes about by doing many of them.

it is not nearly as inefficient as many people think, and that is easily demonstrated mathematically.

All of the change procedures in the table below change 30% of the total water volume. It is done as one x 30%, 2 x 15%, etc., and the way down to continuous changes. The only math math assumption is that the water mixes completely between changes.

One can see that the amount of any impurity remaining is 70% with one big change, and 74.08% with continuous changes. Everything else is in between. Those are VERY close together and not worth of worry, IMO.

In reality, the results can be even better because one can take out the old water just upstream of where the new water enters.

 

[Randy Holmes-Farley Verified Community Expert]

Every tank I’ve managed over 24 years has no water changes in mind. My only failure was one of my first tanks that had a 6/7” dsb, and even that lasted 6+ Years

This tank was setup 8 years ago. There hasn’t been a water change in at least 4 years

Obviously water changes are not "needed" since there are many tanks that do not do water changes. If that is the literal question, then the answer is unambiguous: they are not "needed".

But there are two related questions that are important:

1. If one is not going to do water changes, what all is needed to attain a tank the reef keeper is happy with given the existing creatures and husbandry practices it currently uses.

2. For any given tank not doing water changes, is the tank going to be better (or worse) in any detectable way by doing water changes. No picture of a tank can answer that question.