Help me calculate KALK dosing.

JPG Corals · Feb 14, 2026

I am trying to dose KALK (BRS kalk pharma grade) for the first time, and could use some assistance.

I have a UNS r60 tank (Total Volume (Including Sump): 45.5 gallons)
I estimate i have 40Gal. total water volume after displacement.

I am currently losing about .1 - .2 dKH daily, I will error on the lower side of .1dKH
I want to dose fully saturated Kalk, via Apex DOS.

From what i have calculated, i should be dosing roughly 130mL daily.

Also, should i have concerns about raising any other parameter before dosing this?
-dKH 8 (this is the level i want to maintain)
-Calcium ~425ppm
-Mag ~1230ppm

Thanks.

rishma · Feb 14, 2026

looks good. Your dose is right. You’ll want to dose 1-2 ppm magnesium each month (or each ~3500 ml of kalk dosed). Don’t bother testing magnesium, home tests are too inaccurate to bother with.

JPG Corals · Feb 14, 2026

rishma said:
looks good. Your dose is right. You’ll want to dose 1-2 ppm magnesium each month (or each ~3500 ml of kalk dosed). Don’t bother testing magnesium, home tests are too inaccurate to bother with.

Awesome, thanks for the confirmation.
Yes, I am aware of the inaccuracy of Cal/Mag test. I figured my range was is in the ballpark but wanted to confirm i didn't need to raise anything before starting the KALK.

Thanks for the heads up on the "1-2ppm" Mag addition monthly. I would not have thought of this.

Any recommendations on dosing 24/7 or nightly? (to minimize PH swing)
I am leaning toward 24/7...

rishma · Feb 14, 2026

JPG Corals said:
Awesome, thanks for the confirmation.
Yes, I am aware of the inaccuracy of Cal/Mag test. I figured my range was is in the ballpark but wanted to confirm i didn't need to raise anything before starting the KALK.

Thanks for the heads up on the "1-2ppm" Mag addition monthly. I would not have thought of this.

Any recommendations on dosing 24/7 or nightly? (to minimize PH swing)
I am leaning toward 24/7...

130ml or even 2x that is not enough to significantly influence pH so there isn’t really a strong argument for nightly vs 24/7. I’ve dosed kalk nightly for most of 30 years just because that’s the way I’ve always done it. You really cannot go wrong either way.