Kalkwasser not keeping ALK up

[Jacob D]

Randy (and others),

I have been happily using Oceanic and Kalkwasser for top off for a while now (close to a year). I randomly test my CA and ALK, these days my CA is still high (450-500 ppm) while ALK has dipped a little (2.6 m/eq). My standard regime is 3 tblspns of Mrs. Wages to 5 gallons of RODI water. I think a combination of less evaporation and my corals becoming larger has tipped the balance on the ALK (which has usually been right at 2.9 or just over) and I'm not keeping up any more, in fact I have always wanted to be around 3.5 m/eq but settled for 2.9.

So, on to my questions... Could switching from Kalkwasser to a topoff of PartB (possibly a semi-diluted mixture in RO water) be a solution to my low alk? How does your PartB recipe compare to saturated limewater? I have not tried the vinegar method with my Kalkwasser yet, which may be a better place to start.

I'm also planning to be running Phosban again soon so I'm bracing for another hit on my already low alk and looking for ways to stay in the comfort zone without having to do manual daily dosing of anything.

Advice, thoughts, criticism welcome, Thank you.

 

[steve the plumb]

you should try Randys alk formula baking soda with ro water.Look in his articles and you will find the formula.

 

[jdieck]

Because of the usually high Calcium in the Oceanic Salt, my preferred supplement will not be Kalk mix. The Kalk adds Calcium and Alkalinity so higher additions of Calcium may help depress Alkalinity by abiotic precipitation.
If you want to use a high Calcium salt then you shall try an unbalanced supplement like a two part but adding more of the Alkalinity one and the Calcium portion only as needed when needed.
Other alternative will be to use Baking Soda or Baked baking soda for your Alkalinity and adjust Calcium only as necessary.


Have you tried a more balanced salt?

 

[Randy Holmes-Farley]

One good option is to continue the limewater as is, but every day or two, give it an additional boost with a baking soda solution, at least until the calcium comes down a bit. Then you could use both parts of the DIY two part system in addition to the limewater, since it appears that the demand may be more than limewater alone can support.

Increasing the evaporation (with fans, for example), may also allow more limewater to be used, and that may solve your problem.

 

[Jacob D]

Thanks all.

Basically what was suggested by Steve and JDieck was what I was wondering about in my post above.

Could switching from Kalkwasser to a topoff of PartB (possibly a semi-diluted mixture in RO water) be a solution to my low alk?

MY concerns with that are:
a) I don't know how much my CA will drop, weekly water changes may not keep it high enough. (only one way to find out I guess)
b) I'll be dripping in way too much PartB (or whichever the ALK part is) - could I dilute the recipe or use less baking soda so I don't overdose by using it as top off water?

Randy,

I see you suggest to continue to use limewater AND both parts of your recipe. Wouldn't my calcium be through the roof in doing so? Any reason not to stop using limewater and just switch to the ALK part?

 

[Randy Holmes-Farley]

I don't know how much my CA will drop, weekly water changes may not keep it high enough. (only one way to find out I guess)

Trial and error is the best way. It is slow,and will take a while. A typical demand might be on the order of 10 ppm calcium per day.

The alkalinity supplement can be diluted in fresh water as much as you want to.

Any reason not to stop using limewater and just switch to the ALK part?

That is fine. But since you may want to go back to it, keeping it going is fine too.

After calcium has declined to normal, if limewater is not maintaining alkalinity, it is also not maintaining calcium (unless you artificially boost it with water changes using a high calcium salt). That calcium drop effect takes longer to notice, but it is always the case. That is why I suggested adding both parts of the two part.

This article described such issues:

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