Any way to get away with not doing water changes?
- Thread starter whatnot45
- Start date
I find regular water changes relatively easy to do, so I do them. But, mathematically, I'm not convinced that they do all that much, other than with the occasional replacement of a significant portion of the water volume. I have toyed with doing this, say every year, by replacing say 90% of the volume - it's just not easy to do logistically.
Do a bit of math based on a weekly 10% water change, figure out dilution effect, and you find that waste buildup is still a problem unless you accept that filtration methods can keep it in check. And if that is true, then why do a W/C; how much time does it buy you? Similarly, a water change is not going to magically restore the right element balance to your tank, for the same 'dilution' reason. Yes, it will add some back to the system; but how is this any different than dosing a trace element additive (which popular opinion now frowns upon).
The trouble, of course, is that we are unable to properly measure all the things in our tanks, and must therefore rely on proxies. Water changes are just one such proxy.
Do a bit of math based on a weekly 10% water change, figure out dilution effect, and you find that waste buildup is still a problem unless you accept that filtration methods can keep it in check. And if that is true, then why do a W/C; how much time does it buy you? Similarly, a water change is not going to magically restore the right element balance to your tank, for the same 'dilution' reason. Yes, it will add some back to the system; but how is this any different than dosing a trace element additive (which popular opinion now frowns upon).
The trouble, of course, is that we are unable to properly measure all the things in our tanks, and must therefore rely on proxies. Water changes are just one such proxy.
Gary Majchrzak
Team RC
Every aquarium is vastly different.
If you are feeding a large fish population and/or hungry anemones it's easy to see how water changes benefit certain corals in the same system.
All you have to do is monitor phosphates and growth to prove this
I don't find this thread to be a 'no water change vs water change' thread and I feel that kind of thinking will not be very productive.
If you are feeding a large fish population and/or hungry anemones it's easy to see how water changes benefit certain corals in the same system.
All you have to do is monitor phosphates and growth to prove this
I don't find this thread to be a 'no water change vs water change' thread and I feel that kind of thinking will not be very productive.
Aqualund
New member
And see, as much as I respect your knowledge and vast experience on the matter, I can right now say to you that I have done no water changes on two separate 2k gallon heavily stocked coral propagation systems for 5 years now with no ill effects on water quality. (phosphates are .08, respectively)
Pests are another issue.
So yes, every system is different, but there seems to be some question to the validity of the idea that you can have a successful reef system with few or no water changes. I'm simply stating that you can.
Others disagree with this, which is fine.
Pests are another issue.
So yes, every system is different, but there seems to be some question to the validity of the idea that you can have a successful reef system with few or no water changes. I'm simply stating that you can.
Others disagree with this, which is fine.
CStrickland
New member
This article has some good illustrations of how diff wc regimes replace elements and dilute waste products: http://reefkeeping.com/issues/2005-10/rhf/
For example:
Alkalinity as a function of time when performing very large daily water changes of 0% (no changes), 5%, 10%, 15% and 30% of the total volume EACH DAY. [in a low alk consuming tank]
Nitrate concentration as a function of time when performing daily water changes equivalent to 0% (no changes), 7.5%, 15% and 30% of the total volume each month
Sorry those are so big! idk how to make the pics diff sizes
For example:
Alkalinity as a function of time when performing very large daily water changes of 0% (no changes), 5%, 10%, 15% and 30% of the total volume EACH DAY. [in a low alk consuming tank]
Nitrate concentration as a function of time when performing daily water changes equivalent to 0% (no changes), 7.5%, 15% and 30% of the total volume each month
Sorry those are so big! idk how to make the pics diff sizes
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It's late, and my brain is mush - but I don't see why at higher percentages, the lines would curve. I'd think they'd be straight lines. Otherwise, it nicely illustrates my point that W/C simply postpone the inevitable - if you accept that we are not truly able to process wastes fully through current filtration methods.
mhucasey
Acros & wieners, oh my!
Nitrate breaks down fully to nitrogen gas and bacterial biomass in a real world reef tank. The above curves only really apply to a freshwater tank. Many reef keepers have to add nitrate because their system is very efficient at removing them.
CStrickland
New member
The graphs are for real world reef tanks.
Randy explains it better than I can in the linked article from which they were sourced, but it is pretty long. If you mean the lines in the alk graph I think that it's like the alk finds its level, so that tank's using 2meq/l of alk per day and a 30% daily change can keep it steady at 3.5 ish. So the lesser changes continue to drop cause they aren't keeping up, and the larger ones drop less (curve up). Lol dunno if that made it clearer
I'm sure that nitrate processing and alk depletion and everything else varies widely by tank. The experiments are obvi not meant to predict a result any of our particular tanks, rather to illustrate a general trend. Tthe article is worth a read when the brain is unmushed
Randy explains it better than I can in the linked article from which they were sourced, but it is pretty long. If you mean the lines in the alk graph I think that it's like the alk finds its level, so that tank's using 2meq/l of alk per day and a 30% daily change can keep it steady at 3.5 ish. So the lesser changes continue to drop cause they aren't keeping up, and the larger ones drop less (curve up). Lol dunno if that made it clearer
I'm sure that nitrate processing and alk depletion and everything else varies widely by tank. The experiments are obvi not meant to predict a result any of our particular tanks, rather to illustrate a general trend. Tthe article is worth a read when the brain is unmushed
mhucasey
Acros & wieners, oh my!
It's a model, based on calculating a system where nitrate is only removed by water changes. That is clearly stated in the article. If you have a reef tank with a reasonable amount of live rock or a deep sand bed nitrate breakdown to nitrogen gas reduces nitrate. If you add a carbon dosing system and a skimmer you can reduce nitrate to nothing without a water change rather quickly.
Using Nitrate reduction as a reason for performing water changes is just incorrect. Fish only systems, it may be needed. Reduction of toxic elements and phosphate, or replenishment of trace elements may be legitimate arguments for changing reef tank water.
Using Nitrate reduction as a reason for performing water changes is just incorrect. Fish only systems, it may be needed. Reduction of toxic elements and phosphate, or replenishment of trace elements may be legitimate arguments for changing reef tank water.
CStrickland
New member
Ah, I see. I wasn't saying nitrate is the only reason to change water because there's no other way to remove it. I chose those graphs for examples because one shows stuff being removed and the other shows stuff being replaced. Those are the 2 basic issues that people address with waterchanges, and the graphs illustrate them reasonably well.
Like I said, nitrate processing and alk depletion vary wildly, those particular elements are not my point. Had I used a pic of phosphate reduction, someone would've said run gfo, toxic elements - run carbon. There are many ways to adjust husbandry to compensate for changing less water. That's really the takeaway from these threads: you can not do water changes but you'll be doing something to replace and remove.
Like I said, nitrate processing and alk depletion vary wildly, those particular elements are not my point. Had I used a pic of phosphate reduction, someone would've said run gfo, toxic elements - run carbon. There are many ways to adjust husbandry to compensate for changing less water. That's really the takeaway from these threads: you can not do water changes but you'll be doing something to replace and remove.
mhucasey
Acros & wieners, oh my!
There is a lot of great info I the article, primarily the data that shows how the size of the water change is essentially unimportant, just the cumulative quantity.
CStrickland
New member
Yup.
I also got from it that just changing water isn't going to keep up unless you go cray with the amounts you're changing. But like you said, we've got other stuff going on too.
I also got from it that just changing water isn't going to keep up unless you go cray with the amounts you're changing. But like you said, we've got other stuff going on too.
I tend to agree. Though I'm unconvinced that a water change offers a more precise methanism for trace replenishment than dosing does. Ironic, to me at least, that the former is generally promoted where the latter is discouraged.
reefgeezer
Active member
I agree with the assertion that water changes are not needed to manage nitrate, phosphate, calcium, alkalinity, and magnesium in our systems. I'll stipulate that dissolved organics are relatively unaffected by small water changes even when used to siphon detritus.
How is everyone who is not doing water changes handling the maintenance of minor trace elements that we don't measure? IMO, this is the key issue that gets skipped over when arguing about the easy stuff i.e. nutrient control & major trace element management.
How is everyone who is not doing water changes handling the maintenance of minor trace elements that we don't measure? IMO, this is the key issue that gets skipped over when arguing about the easy stuff i.e. nutrient control & major trace element management.
This is THE question I have been wrestling with for years. Folks generally dismiss dosing based on 'don't dose what you don't measure', and I would tend to agree (though triton may change things); BUT, how is replenishing trace elements with water changes really any better? OK, there's a minor dilution effect, but it's really minor. Assuming one doses with an element mix that mirrors the salt mix (also artificial) I see no defendable reason to excoriate one and support the other. Just my opinion, of course.
Green Chromis
New member
:fish1: Hi all. beautiful tanks their Glenn and Casey. I do water changes using NSW, and I do agree with you that if you are diligent and keep up with all the elements need to maintain the correct levels in NSW you can have a very beautiful system. I have a question though, when you add all these elements in the correct concentrations to mimic NSW, are you doing a water change or are you changing the water? :fish1:
reefgeezer
Active member
Cool. What trace elements are you dosing?
