Figuring out how much kalk to dose

[bfortune76]

For the past 3 years I have dosed BRS 2 part and I feel like I could never get it right. I ran out several months back and have just been doing water changes with reef crystals. Some of my SPS are super hardy and others have shown signs of low alkalinity so I decided to try something different and go with kalk. I have the general idea of adding it to the ATO line but kind of want to use my doser instead and need to figure out how much to use and how often to dose. Or just mix it with my ATO water like everyone else lol.

Part of my frustration is my tank has always sucked more alk than calc and everywhere I read says you should dose in equal parts but I always end up dosing twice as much alk. I bought bottles of reef fusion 1 and 2 to get my levels square and some powdered kalk today and took my initial levels.

Mag 1300
CALC 395
Alk 5.6

I dosed and re tested again getting

CALC 420
Alk 6.5

I didn't mean to go a whole point and dosed according to the seachem calculator. Calcium went up to 420 like planned but alkalinity jumped .9 instead of the intended .5. Tomorrow at this time I will test again and get my consumption then the next few days bring up alkalinity to 8 and prepare for the lime dosing.

My question is why is my alk not equally drawn? If it is consumed faster than the calcium will this be a problem dosing kalk? And are there any calculators for figuring out kalk mixing levels vs tank size vs consumption? I couldn't find any.


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[mcgyvr]

It is VERY normal to need to dose more alk than cal...
Plenty of others are in the same boat including myself...

In a perfect world consumption should be equal...Our tanks are rarely perfect environments and as such you simply dose as needed....IMO stick with 2 part so you have control

 

[nycman]

I too dose two part in different doses. I just keep reprogramming my electronic doser to tune my alk and calc. I also put 1.5 teaspoons of Kalk per gallon in my ATO container. And recently I added a calc reactor b/c I was using a gallon a week of each of the two parts - too much work. So now I run my calc reactor fairly strongly, and then fine tune with the two part, which now I go a couple of months before i deplete the gallon containers. My alk is 8.3, and calc 420.

 

[thegrun]

Ditto the above, your usage should be fairly close but rarely will they be exactly the same. If your salt mix is different than where your desired calcium and alkalinity levels are the difference in what you dose will be even more pronounced. I use Instant Ocean salt which mixes fairly close to where I keep my calcium (425), but it is quite a bit higher in alkalinity (11.3 versus 8.3), so I need to dose more calcium than alkalinity.
If you know about how much calcium and alkalinity your tank was using on a daily basis and about how much water your tank evaporates daily Bulk Reef Supply has a calculator that will let you know about how strong to mix your kalkwasser. If not I would start with 1/2 teaspoon per gallon of kalk and then adjust the mix as required.