Cal and Alk : A Frustration

[GPB]

I've had my 38 gal. cube tank over a year now. I have good growth of LPS, soft corals, and corraline algae.

I've struggled greatly maintaining Alkalinity and Calcium in this tank.

I've read every article on this topic I can find and I either don't get it , or something is out of whack.

First of all, here are my parameters

PH: Early AM 7.9 Evenings: 8.15-8.2
Alk: 7 dkh
Cal: 340

I use IO salt. Change 20% water every two weeks.

I am dosing 35 ml ea. of C-Balance 2 part daily in addition and my top off water is RO, with 1 tsp of kalkwasser mix added to each gal of water.


It seems to me I'm adding a ton of additives to such a small tank. Is this a case of simply not adding enough 2 part or is something dreadfully out of balance that I;m not getting.

I want to get Alk up to about 9-10 dkh and cal up to 400 .

Also, since I don;t have a kalk reactor, I mix up the Kalk directly to the top off water in jugs, let it settle ,and pour into tank. I'm careful not to get the undisolved Kalk in the tank. I get this nasty film on the water surface. Anybody ever experience this and how do I stop it.

Need some practical advice on how to overcome this issue.

 

[Randy Holmes-Farley]

Most likely the tank is just using the additives as fast as you add them.

That said, you might find it worthwhile to check magnesium and see if it is low. Low magnesium can contribute to excessive abiotic precipitation of calcium carbonate (like on heaters, pumps, etc).

I'd also boost the calcium to 420 ppm using just the calcium part of the C-balance, or just calcium chloride. This calculator shows how much to add, and this article guides you through the process:

Reef chemicals calculator
http://home.comcast.net/~jdieck1/chem_calc3.html


Solving Calcium and Alkalinity Problems
http://www.advancedaquarist.com/issues/nov2002/chem.htm

Once the calcium is up, and you've checked and adjusted magnesium if necessary, try dosing more each day and see if that boosts the alkalinity into the range that you want.

I get this nasty film on the water surface. Anybody ever experience this and how do I stop it.

The tank surface? Do you have an overflow or any sort of surface skimming?

 

[GPB]

The tank surface? Do you have an overflow or any sort of surface skimming?

Yes, I use a remora pro Skimmer that uses the surface skimmer. The overflow doesn't seem to be able to suck the film below the surface.

 

[Randy Holmes-Farley]

Maybe some better positioning of the currents in the tank can help break it up?