Why do you do water changes?

[NS Mike D]

I've been thinking about this, aside from removing detritus from the sand bed, is there any real benefit from water changes (not talking about responding to an accidental)?

If you do a 10% water change, that still leaves 90% of what you were seeking to remove - so it seems that a water change isn't really an effective export method.

If you are seeking to replenish what your tank has consumed, seems that unless your tank is consuming trace elements at the same pace as your salt provides during a water change, you are just guessing. We test for a few major elements/compounds, but other that that, who knows if we are concentrating or deficient in the trace stuff.


I change 5gal of my 29gal every week to two weeks and anecdotally it appears that it's good, but as for actual water chemistry - it's really a guessing game. The white sand and the clean glass and other maintenance I do along with the water change is probably giving me a false sense of a "better" tank.

I test for CA, K, MG, Ammonia, Nitrates, Nitrites, Ph and Phospates. I add Red Sea Reef Foundation ABC as per their charts to my water, but I have to confess, I have no idea the levels of the rest of the elements/compounds. Aside from trying to match sea water, I have no clue what levels are good or bad.


Is my logic off base for questioning if water changes are giving me a false sense of security?

 

[Raul-7]

I'm not sure why the same is not found in the SW hobby [probably the expense of SW]; but in FW we do large water changes to remove DOCs, excess nutrients, toxins and detritus. It makes perfect sense - dilution is the cure for pollution.

 

[Dmorty217]

Most don't use water changes as a means of exporting nutrients (thats what my skimmer is for) If you have a full blown reef you are most likely using a calcium reactor or dosing something. There are some trace elements that are only replaced with water changes so there is benefit there. I do a water change (25%) every month or two just because it seems like the right thing to do! Really I could go every 6-8 months before doing a water change on my DT. QTs eat up water too

 

[madweazl]

I'm not sure why the same is not found in the SW hobby [probably the expense of SW]; but in FW we do large water changes to remove DOCs, excess nutrients, toxins and detritus. It makes perfect sense - dilution is the cure for pollution.

It is the same, people just try to eliminate "work" with technology or chemistry. In the end, I think a more natural approach is better (water changes) but there are so many examples of "successful" setups using just about every method imaginable so there seems to be a plethora of "right" answers.

 

[Raul-7]

Most don't use water changes as a means of exporting nutrients (thats what my skimmer is for) If you have a full blown reef you are most likely using a calcium reactor or dosing something. There are some trace elements that are only replaced with water changes so there is benefit there. I do a water change (25%) every month or two just because it seems like the right thing to do! Really I could go every 6-8 months before doing a water change on my DT. QTs eat up water too

But a skimmer does not remove all the DOCs; I'm sure Randy's article states that it has a strong affinity for amphiphilic compounds.

 

[NS Mike D]

Most don't use water changes as a means of exporting nutrients (thats what my skimmer is for) If you have a full blown reef you are most likely using a calcium reactor or dosing something. There are some trace elements that are only replaced with water changes so there is benefit there. I do a water change (25%) every month or two just because it seems like the right thing to do! Really I could go every 6-8 months before doing a water change on my DT. QTs eat up water too

this is what I am talking about. same here.

 

[Spar]

FWIW, my new tank (450g) has been setup for about 9 months now with only coral and live rock, and a few inverts (i.e. no fish yet). I have only done 1 water change of ~10% in that time period. Coral and other life is doing great.

I used to do daily 1% WC's with my old setup, but am discontinuing that going forward and will likely only do WC's when I need water for QT'ing new fish.

 

[NS Mike D]

But a skimmer does not remove all the DOCs; I'm sure Randy's article states that it has a strong affinity for amphiphilic compounds.

Ok, let's say that is true (and I agree). A water change will only remove a small % of what the skimmer misses. The math, IMO, is fairly basic. Isn't the rest of the life in the tank that is consuming the remaining compounds?

 

[j_mazzy]

what if you used a skimmer and algae scrubber.... if you dosed what you needed would you ever really need a water change?

 

[jason2459]

Basically it comes down to Importing stuff and Exporting stuff.

Good read by Randy Holmes-Farley
Water Changes in Reef Aquaria
http://reefkeeping.com/issues/2005-10/rhf/

I'm on an automatic water change setup now and do around 1% daily.

If someone is in a drought stricken region I can see trying to avoid them. Only person I know of so far to be successful, IMO, at not doing water changes is GlennF. So, if someone wants to go this route check him out and the DSR method.

 

[NS Mike D]

what if you used a skimmer and algae scrubber.... if you dosed what you needed would you ever really need a water change?

I would think you still need to address the detritus build up in the sand bed. As far as I know there are two ways to remove detritus from the sand bed: Strong flow and stirring the bed so it gets caught in the filter sock in your sump and siphoning the bed during a water change.

That is my understanding, but I don't have years of experience (which is why I started this thread)

 

[jason2459]

I would think you still need to address the detritus build up in the sand bed. As far as I know there are two ways to remove detritus from the sand bed: Strong flow and stirring the bed so it gets caught in the filter sock in your sump and siphoning the bed during a water change.

That is my understanding, but I don't have years of experience (which is why I started this thread)

These pictures say it all

Carbon dosing for healthy bacteria to remove NO3

Liquid iron dosing to bind PO4

Powerfilter te remove detitritus

I even dose PO4 and NO3 to control these values.


Happy Reefing, GlennF.

 

[Timfish]

Every animal needs fresh water. A couple decades ago when I started my maintenance business what I realized doing cold calls was the common denominator for successful systems was not equipment or methodology but consistent maintenance including water changes. Now I know that's probably the best way to get rid of refractory DOC along with removal of any nuisance algae. With multiple systems, fish and corals decade old and no skimmers, reactors, chemicals or supplements (I use auto feeders to add aragamight) I'm inclined to think they're critical to long term success.

 

[NeilFox]

I think it can be done both ways. Back in the day, Alf Nielson and Peter Wilkens suggested small and infrequent water changes. The salt was pretty basic Instant Ocean then. With the newer salt mixes a lot of the guesswork is taken out. It's possible to run a tank without water changes, but you need to stay on top of your chemistry and dose accordingly. For the average hobbyist a water change regimen makes things pretty simple. I do water changes now because it is easier. In the late eighties and early nineties I had a pretty nice reef. I only changed a little water when I cleaned up the bottom. The idea was that my water would be more stable and the salt mix couldn't keep up with demand for calcium and trace elements through water changes alone.

 

[Raul-7]

Ok, let's say that is true (and I agree). A water change will only remove a small % of what the skimmer misses. The math, IMO, is fairly basic. Isn't the rest of the life in the tank that is consuming the remaining compounds?

I do not believe so; but we must ask what a build of DOCs results in.

For example, a build up of DOCs has been known to cause stunting and poor development especially in fry. Hence why Discus breeders change their water religiously and frequently.

Does a buildup of DOCs cause poor coral growth and fish development in SW?


I mean we focus on nutrient replenishment but I think in WCs; toxin removal is just as important.

 

[NS Mike D]

I do not believe so; but we must ask what a build of DOCs results in.

For example, a build up of DOCs has been known to cause stunting and poor development especially in fry. Hence why Discus breeders change their water religiously and frequently.

Does a buildup of DOCs cause poor coral growth and fish development in SW?


I mean we focus on nutrient replenishment but I think in WCs; toxin removal is just as important.

I don't disagree, I just think skimming, carbon and other export methods are more effective than typical water changes.


Think of it this way. How many reefers will go a month between a water change? How many would turn off their skimmer or refugium for a month?

 

[jason2459]

keep in mind water changes should not and most likely can not be relied on for all nutrient import or export especially as the tank size increases.

That said my 20 gallon tank with softies is maintained 100% on just water changes done weekly. If I miss a week here an there no big deal. No other filtration or export is done on it. Heater and a couple power heads is all that's in there.


Also, keep in mind skimmers are not very efficient at mechanical filtration.

 

[2_zoa]

Is my logic off base for questioning if water changes are giving me a false sense of security?

Nope, not in my opinion. I for one don't like doing water changes. Not cause I'm lazy but, because I ask the same questions to myself.

I think this is where triton enters the picture. They do the testing for you and you add only what you need. Regardless of what equipment any setup has or feeding regiment.

 

[d2mini]

If you are seeking to replenish what your tank has consumed, seems that unless your tank is consuming trace elements at the same pace as your salt provides during a water change, you are just guessing. We test for a few major elements/compounds, but other that that, who knows if we are concentrating or deficient in the trace stuff.

This is the thought behind the Triton method.
So no water changes, but all minor and major trace elements are replenished in balance through daily dosing.

 

[Raul-7]

That begs the question, does carbon remove DOCs?