water changes?

[new2scrub]

i would like to start a debate on water changes when using a scrubber. i know santa says not to do them but i am still tempted sometimes. but i DO love that i have not had to lug buckets or pay $50 for a bag of salt in 5 weeks now. does anyone have a tank that has gone for years without them here? does anyone do weekly waterchanges still? my thought would be to do a 10% waterchange every 2-3 months just to freshen things up and remove some of the green tannins from the algae in the water. but maybe that is a waste of time? lets debate!

[mikepao13]

Good question....

I think when you have a successful ATS, a water change may be necessary just to clean / remove the dead "dust" type algae that all over the bottom of the sump.

[redneckgearhead]

THIS IS ONLY MY OPINION! But I think IF you dont do water changes IN A REEF TANK you should dose the trace minerals that get used up. I REPEAT JUST MY OPINION! (some people get really upset about this topic, amoung others) :D The guy that had my tank before me NEVER in five years did a water change! NOT CONDONING THIS BEHAVIOR JUST THE EXPERIENCE THAT I HAD (granted the tank was in horrible shape when i took it over) but I agree that sometimes you might have to clean the "silt" out that acumulates inthe bottom of the tank and sump.

[Vannpytt]

What I came to rest with is. If you don't dose anything but food for the system you won't need a waterchange for anything at all. However, if you dose trace elements you will have to preform waterchange to balance the salts out with what you are adding. How large and how often I'm not sure at all about.

[SantaMonica]

I think when you have a successful ATS, a water change may be necessary just to clean/remove the dead "dust" type algae that all over the bottom of the sump.

This is why the best setup is no sump at all. Sumps don't do anything biologically beneficial for a tank; they only reduce the food, and increase the nutrients, by virtue of organic particles settling on the bottom of the sump. Of course, a strong enough scrubber will overcome the extra nutrients, but the settled particles could have gone to feeding your corals or small fish. Best you can do is to keep strong circulation in the sump. However your bigger problem is really fish-waste settling, not algae, because fish-waste is composed of much larger and heavier particles. Nevertheless, you should be happy to know that all this stuff really does not "accumuate" forever; once it decomposes in the sump, it's basically just dirt, and does not do any more harm, except for being a rough surface that traps more waste easily. So if you scrub strong enough, you can never clean your sump again if you don't want to.


IN A REEF TANK you should dose the trace minerals that get used up

It's important to differentiate between minerals and nutrients. Of course Cal, Alk, Mag (and maybe Str) need dosing, because algae has nothing to do with these. This was the mistake that the "experts" made at the Barrier Reef Aquarium in the 80's... they did not know/think that they needed to replenish these, so they never did, and after a few years the corals were not doing so well. See the studies, below.


If you don't dose anything but food for the system you won't need a waterchange for anything at all. However, if you dose trace elements you will have to preform waterchange to balance the salts out with what you are adding.

This would be correct for FW or for a SW FO tank, but he was asking about a reef tank, and since this includes corals and coralline algae, you would need to add Cal/Alk/Mag/Str as they are used up, because the food you feed does not contain near enough of these. But all the other "trace" things are indeed supplied by the food you feed, and by the algae in the scrubber. The algae, especially, supply key elements for SPS growth: Vitamins (like C) and Amino Acids, which non-scrubber-users have to dose manually.

Here is the Barrier Aquarium info:


1988:

Nutrient Cycling In The Great Barrier Reef Aquarium
http://www.reefbase.org/download/downlo ... ocid=10506 (http://www.reefbase.org/download/download.aspx?type=10&docid=10506)

"The Reef Tank represents the first application of algal scrubber technology to large volume aquarium systems. Aquaria using conventional water purification methods (e.g. bacterial filters) generally have nutrient levels in parts per million, while algal scrubbers have maintained parts per billion concentrations [much lower], despite heavy biological loading in the Reef Tank. The success of the algal scrubbers in maintaining suitable water quality for a coral reef was demonstrated in the observed spawning of scleractinian corals and many other tank inhabitants."

But did you know that they did not add calcium? That's right, in 1988 they did not know that calcium needed to be added to a reef tank. Even five years after that, the Pittsburgh Zoo was just starting to test a "mesocosm" scrubber reef tank to see if calcium levels would drop:

1993:

An Introduction to the Biogeochemical Cycling of Calcium and Substitutive Strontium in Living Coral Reef Mesocosms
http://onlinelibrary.wiley.com/doi/10.1 ... 5/abstract (http://onlinelibrary.wiley.com/doi/10.1002/zoo.1430120505/abstract)

"It was hypothesized that Ca2+ and the substitutive elements Sr2+ and Mg2+ might [!] have reduced concentrations in a coral reef microcosm due to continuous reuse of the same seawater as a consequence of the recycling process inherent in the coral reef mesocosm."

"The scleractinians (Montastrea, Madracis, Porites, Diploria, and Acropora) and calcareous alga (Halimeda and others) present in the coral reef mesocosm are the most likely organisms responsible for the significant reduction in concentration of the Ca2+ and Sr2+ cations."

"Ca is not normally a biolimiting element, and strontium is never a biolimiting element;
HCO3 [alk] can be. It appears that, because of a minor [!] limitation in the design parameters of the mesocosm, these elements and compounds may have become limiting factors. [...] It is surprising that the organisms could deplete the thousands of gallons of seawater (three to six thousand) of these elements even within two or more years [!!].

"The calcification processes are little understood."

So then in the late 90's, the Barrier Reef aquarium start using up it's supply of calcium, and the folks there said "the corals grew poorly". Really. No calcium, and the corals grew poorly. So they "removed the scrubbers" and "experimented with the addition of calcium" sometime after 1998. Then in 2004 it "definitely improved a lot". Really.


Talks about calcium was not added to barrier aq:
http://en.microcosmaquariumexplorer.com ... f_Aquarium (http://en.microcosmaquariumexplorer.com/wiki/Reef_HQ_-_Great_Barrier_Reef_Aquarium)

[Vannpytt]

It's an interesting fact actually SM.

I have a mixed reef, and at the moment I still don't have much corals that eats and competes with alge in the DT (Still only 7 weeks old tank). I have not preformed a waterchange either. My pH is constantly high, around 8,6, and my KH is around 7. A local LFS told me that the buffering capacity for KH looses application >8, and would not really matter much at all if the pH was constantly high, wich was good in itself.

[SantaMonica]

Corals grow the most at pH of 8.4, so if you can stay between 8.2 to 8.6, you'll be good.

[sklywag]

I am on month ten without a water change. But as mentioned in one of the posts. I did clean some crud out of my sump that was actually sort of heavy. Not heavy like sand but it did seem to solidify a little. This is in the empty chamber my skimmer use to be in where my ATS now dumps its water. I keep snails of various types in my sump along with all the pods and a shrimp to keep up maintenance in their. So if you want to count that as a water change you can. I don't. I just replaced water that I lost during that cleaning. About two gallons on a 90g with 30s.

[SantaMonica]

I think everyone will have to do a little adjustment like that once in a while, as I had to after acclimating things for a year... salinity was getting down to .024, so I had to add a little salt.

[new2scrub]

yea think i will keep a bag of salt handy for adjustments only and see how it goes

[Arno]

I know it is a pretty old topic But it am stil interested and have a few questions ?
Know water change how wil it work out in a fowlr tank ?
Easy corals like Kenya Xenia do the need trace elements ?
Reason why I am asking because next year is going to be a bit more busy year than this year.
Currently have vaccination and i am setting up my juwel trigon 190L 50G whit probably a 25 gallon sump.
And I am hoping to set it up for low maintaince.

[SantaMonica]

Trace elements are provided by the food you feed. Kenya and Zenia should do fine. You can do no water changes if your scrubber is working good, and you have snails, crabs, etc for cleaning.

[Arno]

Wel then I am going to do that I will sel my corals that I can keep my calustrea have to leave then en my hamercorAl
.