High Calcium, Low ALK no current dosing.

[Davy Jones]

Hello, as the title says my tank has very high calcium and fairly low alk (day of waterchange)

They are

Cal 557ppm Per hanna checker
Alk 6.68dkh Per hanna checker

I tested these right before my weekly waterchange. I use Reef Crystals salt, and dont do any dosing. (aside from the occasional NoPox)

The tank is fairly new, and all my coral look colorful and healthy but id like to correct my parameters.

What do you recommend on doing to solve this issue?

My new bucket of water tests at 11.2dkh, and i changed about 7 gallons last night. I will test again when i get home but it appears my alk is getting sucked up while my calcium isnt being used at all.

 

[tcoyle]

Recheck the Hanna. It in notorious for high readings.

 

[Davy Jones]

How do i do this?

 

[djbetterly]

Yes, double check with Hanna. I've been using for some time and really have it down. For me the trick was using high quality distilled water. According to Hanna, the calcium checker is so sensitive to calcium that if any calcium traces were left behind by your RODI unit, it will show up or skew the results. I now order 1 gallon of distilled from Hanna every few months and have very accurate results.

 

[Randy Holmes-Farley Verified Community Expert]

It suggests to me that you need to dose some alkalinity. Baking soda is fine. I recommend 7-11 dKH.

This shows how much to use to get to whatever target you want:

http://reef.diesyst.com/chemcalc/chem_calc3.html

And this describes more sophisticated methods going forward:

The Many Methods For Supplementing Calcium And Alkalinity

 

[tcoyle]

recheck with another test kit to make sure its close. But Randy's suggestion is right on as well, your ALK is on the low side.

 

[Davy Jones]

As per the calculator and Randy's suggestion, can i mix the Baking soda into my top off water? My thoughts are this will Allow the addition to be inputed slowly and not raise my ph or alk all at once as well as having things slightly more stable over the week between waterchanges.

What is another good test kit? Nyos? red sea? i bought the Hanna checkers as i wanted an accurate test kit, if its garbage then i wasted money. Wonderful.

Lastly, i understand that calcium and alkalinity have some what of a balance, if i bring my alk up with that also lower calcium or is that not how it works?

 

[tcoyle]

unbaked baking soda won't raise the PH.. I would add the amount in small batches and not in your ATO. Raise your Alk to your desired level slowly as to fast can cause issues with SPS, if you have any.

Hanna is great for ALK, and Phosphate. The Calcium one is good as well, but you have to use lab grade distilled water and do the test exactly as they say. I have used the Red Sea Calcium and like it. I just both the Salifert one to check out and see if I like it better.

If you raise your Alk and are not adding any Calcium supplement to your system, then your Calcium will drop some. I am sure Randy has the calculations of how many DKH of Alk will lower Calcium by X PPM.

 

[Davy Jones]

I will test when i get home what the alk is after my waterchange and go from there! thanks for the help!

 

[Randy Holmes-Farley Verified Community Expert]

FWIW, if you supplement alkalinity and not calcium, calcium will decline as they are both consumed together in a relatively fixed ratio. If you add the equivalent of 14 dKH of alkalinity over time and it comes back to the same starting alkalinity, then calcium will have dropped by about 100 ppm (unless water changes mess with that ratio).

Putting baking soda in top off is fine, and so is manual dosing for the amounts we are talking about here (which are likely low after the initial correction).