Why do we do water changes so religiously if we can remove the nitrates?

[MexiReefer]

I am positive. I'm tired of seeing the same topic beaten to death. No one searches for previous threads on topics.

you can choose not to open the thread

 

[DJ H]

You can’t mimic the ocean

 

[saltyhog]

I have never found any utility in water changes for reducing nitrate and phosphate. No matter how many water changes I've done in the past it never seemed to affect my NO3 or PO4. There are better ways to address those issues. I do water changes every 2-3 weeks but not for nutrient control or alk/calcium/magnesium purposes.

 

[Paul B]

You can’t mimic the ocean

No, we can't, but I think we are all trying to as much as possible in a few gallons of water.
Our fish and corals don't care what we are trying to do, but they want to be in the ocean. The closer we can get to that, the better.

New water with new, clean rocks and 12 hours of blaring light that shuts off instantly with freeze dried or peleted food is not what they had in mind when they were collected.

They came from a place with unlimited, but tiny pieces of "fresh live" food that they could find all day and night.
Their water had plenty of oxygen and a sun that rises and drops every 12 hours along with a tide that is different every day according to the moon which provides it's own light on some nights.
Their home was full of tight crevices, and almost no pure white PVC elbows with a bar code printed on it.

They all had plenty of mates to choose from and multiple places to deposit their eggs which they lay every 10 days or so.

 

[kingkapoor]

The idea of replacing trace elements with 10% water changes is a bunch of hooey.

If youre doing it the "right way" youre probably using RODI water which in theory has absolutely nothing. Then youre adding your favorite mix of salt to the mixture.

If you have a protein skimmer which removes salt water by X amount a week (lets say 2 cups - 1 quart/1 liter weekly), your ATO is probably replacing that amount with more RODI. At a month you could add a quarter cup of salt to make up for the lost balance

 

[vanpire]

A lot of animosity in this thread. I don't know why. If I don't like a thread, I don't read it.

Anyway I think we change far to much water in this hobby. I have been here since the hobby started and I don't remember who came up with that changing water every week thing.
I have a full reef, it is very old and I change water maybe 4 or 5 times a year and I only do it that much because I like going to the beach to collect water.

[/QUOTE

If only I could go to the beach and get sea water......

 

[josephxsxn]

I skipped alot of comments due to some of the possible trolling. So waterchanges are a weird thing it seems like to me.. At first I always assumed we could use a good water change schedule to handle the required imports and exports in the reef tank.. But upon modeling it, it doesnt seem like thats really the case as it functions more like a self-optimizing system.

What I found really interesting in just making a simple math model is that the import and exports really seem to balance out right at about 3-4 months.. Which anecdotally seem to line up with when people say this ugly phase passes, etc.

 

[Tired]

The difficulty is, it's hard to know if an ugly stage goes away, or other signs of maturity appear, because of the water or because of something else. Maturity of the rock counts for a lot. The ugly stage tends to ease up about when the rock starts turning interesting colors instead of being a white, blank slate, for example. You would want to compare signs of stability and maturity between only tanks set up with roughly the same type of rock, because live and dry are going to produce VERY different results half a year out.

 

[Randy Holmes-Farley Verified Community Expert]

I skipped alot of comments due to some of the possible trolling. So waterchanges are a weird thing it seems like to me.. At first I always assumed we could use a good water change schedule to handle the required imports and exports in the reef tank.. But upon modeling it, it doesnt seem like thats really the case as it functions more like a self-optimizing system.

What I found really interesting in just making a simple math model is that the import and exports really seem to balance out right at about 3-4 months.. Which anecdotally seem to line up with when people say this ugly phase passes, etc.

I've modeled water changes pretty extensively, as have others, and I have a different conclusion: they can help quite a lot over time, particularly with things that you cannot or do not measure.

Water Changes in Reef Aquaria by Randy Holmes-Farley - Reefkeeping.com

While I think that nitrate is not a primary reason to do water changes, the modelling is the same for any accumulating material.

The graph below, for example, says nitrate, but it could be any accumulation material (say, an organic toxin or an inorganic ion) and shows what can potentially happen to it over time under various water change scenarios:


Figure 12. 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 (in other words, 0%, 0.25%, 0.5% and 1% per day). In this example, nitrate is present at 100 ppm at the start, and is accumulated at a rate of 0.1 ppm per day when no water is changed.

 

[kingkapoor]

I've modeled water changes pretty extensively, as have others, and I have a different conclusion: they can help quite a lot over time, particularly with things that you cannot or do not measure.

Water Changes in Reef Aquaria by Randy Holmes-Farley - Reefkeeping.com

While I think that nitrate is not a primary reason to do water changes, the modelling is the same for any accumulating material.

The graph below, for example, says nitrate, but it could be any accumulation material (say, an organic toxin or an inorganic ion) and shows what can potentially happen to it over time under various water change scenarios:


Figure 12. 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 (in other words, 0%, 0.25%, 0.5% and 1% per day). In this example, nitrate is present at 100 ppm at the start, and is accumulated at a rate of 0.1 ppm per day when no water is changed.

In this study is there a nitrate removal method in place? Chaeto

 

[Randy Holmes-Farley Verified Community Expert]

In this study is there a nitrate removal method in place? Chaeto

It is a mathematical model that assumes accumulation of nitrate (or other chemical of interest). No matter what else is happening, if something is accumulating, this sort of graph can show what will happen.

 

[kingkapoor]

It is a mathematical model that assumes accumulation of nitrate (or other chemical of interest). No matter what else is happening, if something is accumulating, this sort of graph can show what will happen.

You can make any sort of mathematical model you wish to, however if you arent naming the trace elements and actually conducting a lab study, it is essentially invalid.

 

[kingkapoor]

You can make any sort of mathematical model you wish to, however if you arent naming the trace elements and actually conducting a lab study, it is essentially invalid.
This is entirely negated under the fact that carbon should remove most of the impurities and toxins. And chaeto should remove the nitrates.

 

[josephxsxn]

I know when I did my math model it was meet to be very simple just so I could have some graph of understanding what things may act like. From that perspective it helped me understand that some things you could export or import faster if they are not consumed or accumulating to fast.. Or that some things would self stabilize at higher amounts etc.. I didn't know what may consume trace elements but could assume that they would be consumed or that a toxin would accumulate. Of course doing more then water changes like Carbon also add alot of variables I did not consider in my simple model.

@Randy Holmes-Farley thank you for that link to the WC article. I completely agree with you they can useful for a number of things we may not be able to see. I oversimplified my post as I was thinking more about things which a WC may not export fast enough.

 

[Randy Holmes-Farley Verified Community Expert]

You can make any sort of mathematical model you wish to, however if you arent naming the trace elements and actually conducting a lab study, it is essentially invalid.

lol

I named it nitrate, that makes it valid, especially since it isn't a trace element.

You apparently misunderstand what the point of a model it. It says what can happen, not what will happen under scenarios that do not match the assumption.

In ANY scenario where something is accumulating, water changes will tend to reduce the accumulation. The model shows how much different size and frequency of water changes impact the reduction.

Obviously, if nitrate (or anything else) is not elevated, then water changes are not going to reduce it.

 

[NJDragonet]

 

[the1320god]

Wow... there are lot of things people can find time to argue about.

It has already been said by someone here... in a fish-only system the need for water changes depends on how well you are removing phosphates and nitrates. That can be done with a refugium, GFO, or some other methodology. Since there are no corals, you are not going to be depleting any major chemicals at a rapid rate (Ca, Mg, Alk), or even trace elements for that matter. Those are the two primary reasons for water changes to "remove" toxic substances and to "replenish" nutrients. For those of us dosing reef tanks to minimize water changes, like myself, it is all about knowing the rate of depletion of nutrients. If you have a lot of corals and you are not dosing, chances are you are doing a lot of water changes. If you don't have a lot of corals, in all likelihood, your need for dosing is almost non-existent.

I was surprised it took 3 pages of BS to find someone to answer the op correctly. This is exactly what I was going to say. Nothing absorbing alk, cal, mag, and t elements as this is a "fish only". If you keep nitrates and phosphate in check, the less you need to water change.

 

[mattdg]

BRS just answered some of that question in this video about Tropic Marin Part C, especially if you are dosing 2 part with a heavy bio load.

 

[Sm51498]

There are things that accumulate in your water that are not nitrates or phosphates which could be detrimental to overall health. You cannot directly measure them but many people acknowledge them and take measures to reduce them (carbon and other removal medias). As the article above shows, a diligent water change schedule will do a lot to mitigate that accumulation.

Even in a fish only tank, hormones and other waste compounds can accumulate which you do not want in your tank.

 

[LordJoshaeus]

I do not know how applicable this is to saltwater tanks, but in freshwater planted tanks decaying detritus - whether fish poop, uneaten food, or dead/dying/damaged live plant leaves (not sure if long dead botanicals like driftwood or indian almond leaves cause similar problems) - produce enough localized ammonia and organics to set off algae issues even if the nitrogen cycle prevents ammonia levels in the tank as a whole from reaching problematic levels. There's no logical reason for me to think something similar does not happen in saltwater aquariums if we do not perform water changes and other maintenance often enough to remove said detritus, especially early in the tank's life when the bacteria that process organic waste are not as robustly established.