Alk Swing, but not Calc....

[idisc]

Hello Guys & Gals,

I am having a problem or at least I think that I am. I have a 24G Aquapod AIO tank that has a bunch of SPS and a few LPS and handful of zoas.

Over the course of 1 week between Sunday - Sunday I don't lose any Calc. On the other day I lose at-least 1-2dkh daily... I am currently using Reef Fusion 1 & 2, but only ever dose #2 for the Alk.

It was my understanding that 1dkh of Alk Loss = 20ppm Calc loss. If I am losing assuming 7dkh a week (1 per day, why is my Calc still at 440ish) right before a water change on Sunday. It basically hovers between 460-440 according to API kit.

I know the Reef Fusion kit it supposed to be used together to maintain both alk and calc...but i don't bc I dont want my calc to raise.

I even have noticed a good amount of growth in my sps / lps... Someone help me figure this out please. Although it seems to be working, it does not make sense to me.

 

[redwhiteandblue]

Could it be your sand bed/ rock consuming the alk...

 

[keithhays]

Alkalinity is burned off as a part of nitrification. This is why some form of alkalinity is added to tanks even in fresh water. You will likely need to adjust alkalinity separate from calcium.

 

[markalot]

A swing of 2 KH is only a very small amount of calcium, usually within the range of a hobby grade test kit, especially an API kit. Do yourself a favor, if you're using a balanced 2 part, just test Alk and dose equal parts A and B based only on Alk consumption. Calcium will balance out. Only test Calcium occasionally, just to make sure you are within acceptable limits (400 - 480) or so.

You might also want to consider changing to a better test kit. I like Salifert.

In my opinion.

 

[downbeach]

"Pure calcium carbonate contains one calcium ion for each carbonate ion. That ratio corresponds to 1 meq/L of alkalinity (= 2.8 dKH or 50 ppm calcium carbonate equivalents) for each 20 ppm of calcium. In a real coral skeleton, some magnesium ions get into spaces ordinarily occupied by calcium, so the real ratio in corals and coralline algae is usually closer to 18-20 ppm calcium for each 1 meq/L of alkalinity, and that ratio varies a bit by organism."
From this article:
http://reefkeeping.com/issues/2007-04/rhf/index.php#5

So, the uptake of Ca vs Alk is closer to ~ 20ppm Ca to 2.8dKH or ~ 10ppm Ca to 1.4 dKH. Regular WC's may be keeping up with the amount of Ca and Mg your system is using, but not enough to keep up with your alk demand since it will require more alk, and there is less alk in reserve. So its not unusual for the need to supplement only the alk component until the demand increases. You may see more of a change with a test kit that has a better resolution, i.e. Salifert, Red Sea Pro, etc.

 

[zangmann]

It was my understanding that 1dkh of Alk Loss = 20ppm Calc loss. If I am losing assuming 7dkh a week (1 per day, why is my Calc still at 440ish) right before a water change on Sunday. It basically hovers between 460-440 according to API kit.

20ppm Ca to 2.8dKH/1 meq/L

Simple mistake, I've made the same ...

 

[acrohead500ppm]

API kits are a joke, esp with Calcium, without a decent kit you truely have no idea what your actual level is at.
Again ditch the API. Also some tanks consume each differently, I have noticed tanks packed with tridacnids will eat through calcium like crazy vs a full SPS tank that consumes carbonates at a faster rate than calcium.

each tank is a bit different based on bioload, therefore dosing regimes should be tailored to demands. What the back of the bottle says dosing wise may not be right for you systems needs. That is why you get reliable test kits find your daily swings, and tailor a dosing regime to counter them.