Why does my tank consume more Ca than Alk?

[luther1200]

So I have had my dosing pumps up and running for about 1.5 months now. And I am noticing that I had to bump my Alk timer down 6 minutes less than my Ca timer to keep my levels stable. My Ca has been holding at 400-410. And my Alk at 9.0-9.3 which I think is good. But in order to do this I have to add about 30% less Alk solution than Ca solution. Isn't it supposed to be the other way around if anything? I am getting pretty good growth and everything looks good. I just thought it was wierd. I am using B-Ionic if that matters. If I run both timers for the same amount of time my Alk goes up to the 11dKh range which is a little higher than I would like.


I run my Ca timer 2x a day at 10 minutes each. For a total of 22ml.

My Alk timer runs 2x a day for 7 minutes each. For a total of 15.4ml.

I do weekly 5 gallon WC with Reef Crystals which has an Alk 11 dKh.

So is this pretty normal or does it mean something is going on. My Mg has been 1400 for the whole time with no supplements. Just WC with Reef Crystals which has 1400 ppm Mg when I mix it up.

[bertoni]

Maybe one of the solutions is not at the standard strength. I wouldn't worry, personally, as long as the test results are fine. I'd probably get a second opinion on the kits, though, as testing problems are common.

[luther1200]

Yea, maybe I will get a new Alk kit, the 1 I have is almost up anyway.

[timmmysli]

I want your tank, I've got the opposite problem, my ALK drops so fast and my cal hardly moves.

Do you have Halimeda macro or just heeps of corals as they'll all use lots of calcium.

You might also have something buffering your alk a bit in the tank like your sand/substrate.

Either way I would rather the high alk than a tank that chews Alk like mine does lol

[sedor]

My tank is the same way. Use BRS 2 part I am currently dosing 30ml Ca and 20ml Alk. For a while I fought unbalancing them because I had it in my head that everything had to be equal, but hey if its working don't mess with it right? Your alk test is probably fine I think its normal for this sort of thing to happen.

[cccapt]

When Do Calcium and Alkalinity Demand Not Exactly Balance? (http://www.reefkeeping.com/issues/2004-12/rhf/index.php)

[acrylic_300]

I'm sure someone will argue with what I'm about to say BUT.

When balancing Alk and Ca the higher number will push the lower number down.

To make sense of this you have to know what the balance is.

400Ca = 5.6 Alk
410Ca = 6.9 Alk
425Ca = 9.0 Alk
4.27Ca = 9.3 Alk

From my own experience, running Alk @ 9-10 and Ca @ 400-410 uses a little more CA.

My preference is to run the Ca 440 and Alk 8-9 so that more alk is used.

If you really want to see the difference...bump your Ca up to 500 and see if the Alk falls faster.

On rare occasions when I am able to keep the numbers balanced, they seem to work well enough to drip only kalk. One 10% water change can screw it up depending on what mix.

[luther1200]

Thanks for the reply's. It may have something to do with my substrate. When I do my WC I gravel vac, so over the course of a year or so I loose some sand. So about once a year I add 5 or 10 lbs of new sand. Which I just recently did, so maybe its buffering it.


Acrylic300- Thanks I might try to bump up my Ca a little and see if it happens. But if other people have the same situation going on I am not as worried as I was before. I just thought it was odd.

And my tank is 3 yrs old but its acting like a newer tank. Because I had a bleaching incident about 5-6 months ago so I mostly just have frags and no big colonies os SPS. I have a big Hammer and a 5-6 head Frogspawn but that it. My next largest is a Pagoda. None of which are super fast growers.

[bertoni]

Those balance numbers make no sense. There's no need to "balance" calcium and alkalinity against each other. As long as the calcium, magnesium, and alkalinity numbers remain in their recommended zone, the tank will be fine.

Furthermore, seawater runs about 6-7 dKH or so, and perhaps 350-400 ppm.

There's a number of articles and threads on the topic, if anyone wants to do some reading.

[luther1200]

Thanks I read Randy's article poste above. And I think I was dosing 2 much of both parts,(according to the article) which makes sense. So since I bumped down my Alk and not Ca the Alk went down and the Ca seemed to remain stable, but probably went up slightly.

Overall I think my numbers are just fine, but I am going t turn down the Ca to dose as much as the Alk dosing pump and see if it stabalizes. I suspect it will.