Dialing in kalkwasser

Doob · Apr 4, 2017

Hello all,

I've recently joined the limewater club. I could use some help dialing in the dose.

I'm using Mrs. Wages pickling lime in my ATO, 5 gallon bucket for a reservoir. The first batched I mixed up at about 1/2 tsp per gallon. To be more specific, I added 10 level 1/4 tsp measuring spoons to a VERY full 5 gallon bucket (forgot to set a timer again, DOH).

The trend seems to be a .3-.4 dKH increase per day. It's finally up to where I'd like to keep it, so I need it to stop increasing! My calcium is steady at 375 though, strangely. The test doesn't seem to repeat as well as the alk though (Red Sea titration). It's possible that it's slowly going up and I'm experiencing testing error.

So when I mix up the next batch, how big of a change do i need to make? Cut the amount of lime in half, or just cut back a little? Is there a calculator or will i have to feel it out? Thanks for the help.

Todays parameters:
Cal: 375
Alk: 9.2
Sal: 1.024
Nitrate: between 10 and 25
Phos: undetectable

cmcoker · Apr 4, 2017

Check out this calculator
https://www.hamzasreef.com/Contents/Calculators/KalkContribution.php

Doob · Apr 4, 2017

cmcoker said:
Check out this calculator
https://www.hamzasreef.com/Contents/Calculators/KalkContribution.php

Nice! That's exactly the kind of thing I was looking for.

Except this calculator says the daily ALK contribution is .06dKH, meaning my tank demand is -.24dKH. [emoji23]

.4 ppm calcium contribution explains why I'm not seeing that rise very much.

Could something cause more ALK to be added, like an abundance of CO2 in the water? My ph has always been low, even with a CO2 scrubber.

cmcoker · Apr 4, 2017

Weird, I just started back up on kalk and my contribution number is low too.
Off to test and compare to a couple days ago haha

Doob · Apr 5, 2017

I made a mistake last night. These are more accurate.

Now the ALK addition matches my daily increase. Before starting this I had my ALK usage calculated to 1dKH/day. So something still seems of.

Randy Holmes-Farley · Apr 5, 2017

Doob said:
Nice! That's exactly the kind of thing I was looking for.

Except this calculator says the daily ALK contribution is .06dKH, meaning my tank demand is -.24dKH. [emoji23]

.4 ppm calcium contribution explains why I'm not seeing that rise very much.

Could something cause more ALK to be added, like an abundance of CO2 in the water? My ph has always been low, even with a CO2 scrubber.

CO2 in the source water will, if anything, drop the alkalinity and calcium in the limewater by causing precipitation of calcium carbonate.

As with any additive, unless you know the daily demand, trial and error is the way to determine the dose needed to match the demand. In this case, base it on the tank alkalinity only (not calcium).

What seems to be off? The calculation?

Doob · Apr 5, 2017

Randy Holmes-Farley said:
CO2 in the source water will, if anything, drop the alkalinity and calcium in the limewater by causing precipitation of calcium carbonate.

As with any additive, unless you know the daily demand, trial and error is the way to determine the dose needed to match the demand. In this case, base it on the tank alkalinity only (not calcium).

What seems to be off? The calculation?

The Alk reading dropped about 1dKH/day before adding the lime water. With the limewater, it's increasing .3dKH/day. So I would expect the daily contribution to be 1.3dKH.

Addition:

If I went by the calculator, I could level my Alk off by adding zero lime to the ATO. Or am I missing something?

Randy Holmes-Farley · Apr 5, 2017

Daily demand doesn't work exactly that way. Using limewater raises pH which likely raises demand. Higher alk also causes higher demand.

I'd drop it substantially, however, and see what happens.

Randy Holmes-Farley · Apr 5, 2017

FWIW, your limewater is already pretty weak.

What is the alk now?

Why are you measuring with 1/4 teaspoons? That's a very small spoon lol

Doob · Apr 5, 2017

Randy Holmes-Farley said:
FWIW, your limewater is already pretty weak.

What is the alk now?

Why are you measuring with 1/4 teaspoons? That's a very small spoon lol

That's the only one that I KNEW what it was, the markings on the rest of the set had rubbed off from use. [emoji23]

It seems to be swinging a lot for a 40 gallon with only a few corals. I fee like I'm missing something.