Are water changes over rated?

[Doctorgori]

^^^^Randy that’s what I was looking for, appreciate it…
…and for the record I don’t argue with chemistry degrees :beaming-face-with-smiling-eyes:

 

[fish farmer]

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!

There are a lot of guidelines in this hobby...your mileage may vary.

There are many ways to manage nutrient/Ca/Alk levels, dosing, skimmers, WC, etc.

You have to figure out what works best for your system.

 

[ISpeakForTheSeas]

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.

So, just to check here, is the benefit of small, frequent water changes just the stability of the water parameters, or are there other noteworthy benefits as well?

(I suppose the constant dilution of any potential "pollutants" would be a benefit, but I don't know if it would be a substantial/meaningful benefit or not).

I've been wondering how small, frequent changes (such as weekly) would compare with large changes (either prolonged over a few days/weeks or all at once) every 6 months provided the main parameters stayed stable.

 

[VintageReefer]

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.

You can’t d whatever you want and not do water changes. The tank has to be stable, observation needs to be made, the tank needs to be planned responsibly.

1) I don’t overstock fish, i don’t over feed, I maintain other nutrient control methods, and I am aware of my alk/ca consumption by tracking and I compensate with all for reef in my top off that I add weekly

2) who knows :) ok happy corals are happy, fish happy. Could we be happier ? Maybe. But we are all happy and doing fine.

 

[Randy Holmes-Farley Verified Community Expert]

So, just to check here, is the benefit of small, frequent water changes just the stability of the water parameters, or are there other noteworthy benefits as well?

(I suppose the constant dilution of any potential "pollutants" would be a benefit, but I don't know if it would be a substantial/meaningful benefit or not).

I've been wondering how small, frequent changes (such as weekly) would compare with large changes (either prolonged over a few days/weeks or all at once) every 6 months provided the main parameters stayed stable.

The benefits I see are:

1. One does not need to, and may intentionally not want to, match parameters to the tank. For example, I used small water changes with a low calcium mix to keep calcium down when using kalkwasser since kalkwasser is slightly overbalanced to excessive calcium. Same would be true of Tropic Marin AFR. Making salinity adjustments by not matching salinity also can be useful as when for example, using a two part.

2. I never heated the water, which can save electricity, but also reduces the potential for precipitation of calcium carbonate from a high alk mix.

3. An AWC overall is far less work than manual changes.

4. If one is dosing something that needs to be spread out, it may be possible to mix it into the water changes. Ammonia comes to mind, but it might be tricky to keep the reservoir from cycling it into nitrate. Certainly, one could dose calcium, magnesium, potassium, and even Balling Part C or AF mineral salt this way.

 

[Pistondog]

I've been wondering how small, frequent changes (such as weekly) would compare with large changes (either prolonged over a few days/weeks or all at once) every 6 months provided the main parameters stayed stable.

Nice analysis above in post19 about dilutive effects vs size/frequency of 30% change.
What would you like compared?

 

[Randy Holmes-Farley Verified Community Expert]

1) I don’t overstock fish, i don’t over feed, I maintain other nutrient control methods, and I am aware of my alk/ca consumption by tracking and I compensate with all for reef in my top off that I add weekly

In #1, I think one also needs to consider the many other aspects of water changes, including export of organics (especially those that are not readily skimmer or bound to GAC), salinity accumulations from a two part, ion deviations from using an imperfectly balanced two part system, and consumption or accumulation of ions that one does not normally test for, from potassium to trace elements..

 

[ISpeakForTheSeas]

Nice analysis above in post19 about dilutive effects vs size/frequency of 30% change.
What would you like compared?

Mainly what the pros and cons of each are and if there would be any substantial benefit to one over the other - Randy's response was useful.

Edit: To add, I've also been wondering if doing a larger change every six months would be worthwhile for environmental/seasonal simulation purposes.

 

[rtparty]

Overrated? Not in the least.

I think it’s actually extremely dangerous to promote no water changes for the vast majority of tanks and hobbyists.

Ryan’s latest talk at RAP Orlando does a great job talking about water changes and why they are beneficial.

For decades we’ve seen hobbyists show up, be successful early on, flex they don’t change water and then just disappear. None of them come back and tell you the tank crashed and they exited the hobby. Far too many are afraid to show their failures.

To the OP, you can’t blame water changes for fluctuations if you aren’t performing them correctly to begin with. Your salt should match the parameters of your tank and you should be dosing whether you do water changes or not. With those things in place, water changes won’t influence any parameter enough to cause issues.

 

[Subsea]

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!

Where does the nitrogen go if we don’t do water changes?

Nutrient recycling uses both inorganic nutrients as well as organic nutrients to grow coral & fish.

 

[Reef Puncher]

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.

yea i agree with this. i watched tidal garden video where than said sps tanks will require dosing of things like trace, or strontium to get the best coloration and without water changes and without dosing of these, how do corals get these? its one thing if you ICP and or dose these and then sure you can skip water changes. but if its just youre average joe, not dosing, and then skipping water changes, how would he get this stuff? i guess if you have softies only its not a big deal but SPS and more demanding LPS?? i guess it just depends.

 

[javajaws]

There is more than one way to keep things at the levels they should be. Unpolluted saltwater is just fresh water plus a bunch of elements. Dirty saltwater is just water, some amount of those original elements and pollution. Not doing a water change but instead having enough nutrient export, dosing, and testing is in many cases better than doing a 20% water change. But most likely not cheaper. Different strokes for different folks...

 

[Paul B]

I feel we need to change "some" water but I think the majority of people change way more water than they need to.
Water actually gets better the longer it stays in our tanks,,, sort of and up to a point. (not forever)

Ref: "Water Chemistry for Advanced Aquarist" by Guido Huckstedt.

I believe this. Does a new tank with all new water look good and healthy? No, it doesn't. Do we change 100% of our water? No we don't.

I change about 40 gallons in my 125 gallon tank about 4 or 5 times a year. Now my tank is all LPS and soft corals but it used to be almost all SPS.

This has been my water change interval for over 50 years in the same set up and I have about 40 fish

 

[Troylee]

Mainly what the pros and cons of each are and if there would be any substantial benefit to one over the other - Randy's response was useful.

Edit: To add, I've also been wondering if doing a larger change every six months would be worthwhile for environmental/seasonal simulation purposes.

This is what I do! I see my sticks perk up if I wait a long time to change water… I was doing them faithfully every other week… now I’m doing them every other month… I noticed slower growth with every other week.. this leads me to think maybe one large change once a month would be my sweet spot! I don’t change water to lower nutrients cause my tank runs really low I do them to replenish trace elements whether I need them or not! I’m not into dosing a ton of stuff or wasting money on icp tests.. I know Jason Fox does one large change of like 800 gallons every so often and that’s it..

 

[shakacuz]

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.

not to mention how salt prices have increased over the years/months. i can't fathom how much $$$ goes towards water changes on high water volume tanks/systems. or for those who do WC's and also dose trace elements. just adds uneccessary spending to the hobby.

i'm on the 0 water changes and dose trace elements as per ICP results with the #reefmoonshinermethod

 

[Jasonak]

I used to do water changes monthly when I did not dose. I now do them every 3-4 months. Im dosing calcium, alk and mag and also adding trace element's.

 

[Jasonak]

not to mention how salt prices have increased over the years/months. i can't fathom how much $$$ goes towards water changes on high water volume tanks/systems. or for those who do WC's and also dose trace elements. just adds uneccessary spending to the hobby.

i'm on the 0 water changes and dose trace elements as per ICP results with the #reefmoonshinermethod

Moonshiners seems little complicated to me,,im lazy :) BUT theres a guy in one of the fall growout comps who does it and it definitely looks like it works. His stuff looks great!

 

[Troylee]

Moonshiners seems little complicated to me,,im lazy :) BUT theres a guy in one of the fall growout comps who does it and it definitely looks like it works. His stuff looks great!

Salt is much cheaper than all them supplements and icp tests…

 

[tritonpower]

The benefits I see are:

1. One does not need to, and may intentionally not want to, match parameters to the tank. For example, I used small water changes with a low calcium mix to keep calcium down when using kalkwasser since kalkwasser is slightly overbalanced to excessive calcium. Same would be true of Tropic Marin AFR. Making salinity adjustments by not matching salinity also can be useful as when for example, using a two part.

2. I never heated the water, which can save electricity, but also reduces the potential for precipitation of calcium carbonate from a high alk mix.

3. An AWC overall is far less work than manual changes.

4. If one is dosing something that needs to be spread out, it may be possible to mix it into the water changes. Ammonia comes to mind, but it might be tricky to keep the reservoir from cycling it into nitrate. Certainly, one could dose calcium, magnesium, potassium, and even Balling Part C or AF mineral salt this way.

As Randy discussed the issue with 2 part and high salinity will become a problem over time. The bigger the tank and the bigger the corals, the faster it will occur. Salinity will always rise with 2 part then you will need to do water changes to bring it down. You can also just remove saltwater and replace with RO but then you deplete the trace elements.

My tank was ok for the 1st couple years but then the salinity battle began. As I am setting up a new tank I will use both kalk and 2 part to hopefully not have as much issues with salinity but I will still need to do occasional water changes to keep it stable.

 

[javajaws]

As Randy discussed the issue with 2 part and high salinity will become a problem over time. The bigger the tank and the bigger the corals, the faster it will occur. Salinity will always rise with 2 part then you will need to do water changes to bring it down. You can also just remove saltwater and replace with RO but then you deplete the trace elements.

My tank was ok for the 1st couple years but then the salinity battle began. As I am setting up a new tank I will use both kalk and 2 part to hopefully not have as much issues with salinity but I will still need to do occasional water changes to keep it stable.

Yeah - it's one big balancing act. You COULD try to manually correct using RO water and correct other values with dosing and ICP testing. But really at that point a few water changes back to back to reset everything is probably easier and cheaper.