Considering kalk with AFR

joseph.timbs · Dec 29, 2025

I’m thinking of adding kalkwasser as my 3 part consumption increases. I’m using AFR and aquaforest reef salt. The two have my alk at 7.5 calcium 510 magnesium idk I imagine around 1400- 1450. Don’t really test it anymore except in ICP. If Randy doesn’t care for Mag testing, I don’t either. Anyways, my oh is decent 8.1-8.2. With the AFR and salt keeping the Calcium level above 500 I’m not sure enough to not ask opinions. Thought about AFR in the Day and Kalk at night. The reason is I’d like the PH boost and not dosing quite as much trace with AFR only half the time. Since the kalkwasser doesn’t contain traces. That’s my thought anyways. There’s Kalk +2, kalk and a brightwell product for alk and PH boost for considering the calcium. Would appreciate any help/opinions.

rishma · Dec 29, 2025

joseph.timbs said:
I’m thinking of adding kalkwasser as my 3 part consumption increases. I’m using AFR and aquaforest reef salt. The two have my alk at 7.5 calcium 510 magnesium idk I imagine around 1400- 1450. Don’t really test it anymore except in ICP. If Randy doesn’t care for Mag testing, I don’t either. Anyways, my oh is decent 8.1-8.2. With the AFR and salt keeping the Calcium level above 500 I’m not sure enough to not ask opinions. Thought about AFR in the Day and Kalk at night. The reason is I’d like the PH boost and not dosing quite as much trace with AFR only half the time. Since the kalkwasser doesn’t contain traces. That’s my thought anyways. There’s Kalk +2, kalk and a brightwell product for alk and PH boost for considering the calcium. Would appreciate any help/opinions.

I use AFR during the day and kalk
At night. About 60% of my alkalinity is from AFR. I limit my kalk use based on the size of reservoir (I want it to last 45 days). I have been doing it this way for most of 5 years. The only other thing I do is dump in a little magnesium on Sundays to account for the lack of Mg in the kalkwasser. My ICP shows trace in good shape in my tank.

I don’t suggest using the kalk+2, not a good product. I just use regular kalk. I use the BRS stuff these days.

rishma · Dec 29, 2025

I’ll expand on my trash talk about kalk+2. The magnesium hydroxide in it is insoluble. Thats why you cannot mix kalk and magnesium. It won’t dose any useful amount of magnesium to the tank. Brightwells own analysis indicates it would only supply 0.05 ppm Mg for each 20ppm Ca from saturated liquid. To get their full claimed amount of 0.5ppm Mg per 20 ppm calcium yiu would have to dose some suspended solids. This makes no sense to me. Furthermore a reef needs 1-2ppm Mg for every 20 ppm calcium dosed.

The amount of Mg provided by kalk+2 is not meaningful.

Ok, glad I got that off my chest.

joseph.timbs · Dec 30, 2025

rishma said:
I’ll expand on my trash talk about kalk+2. The magnesium hydroxide in it is insoluble. Thats why you cannot mix kalk and magnesium. It won’t dose any useful amount of magnesium to the tank. Brightwells own analysis indicates it would only supply 0.05 ppm Mg for each 20ppm Ca from saturated liquid. To get their full claimed amount of 0.5ppm Mg per 20 ppm calcium yiu would have to dose some suspended solids. This makes no sense to me. Furthermore a reef needs 1-2ppm Mg for every 20 ppm calcium dosed.

The amount of Mg provided by kalk+2 is not meaningful.

Ok, glad I got that off my chest.

Thanks man. Awesome help, just the stuff I was wondering about with sustained success. I was thinking Kalk+2 would be the way to go. Now, not so much lol. Thanks

Rosengrant826 · Dec 30, 2025

joseph.timbs said:
Thanks man. Awesome help, just the stuff I was wondering about with sustained success. I was thinking Kalk+2 would be the way to go. Now, not so much lol. Thanks

rishma said:
I’ll expand on my trash talk about kalk+2. The magnesium hydroxide in it is insoluble. Thats why you cannot mix kalk and magnesium. It won’t dose any useful amount of magnesium to the tank. Brightwells own analysis indicates it would only supply 0.05 ppm Mg for each 20ppm Ca from saturated liquid. To get their full claimed amount of 0.5ppm Mg per 20 ppm calcium yiu would have to dose some suspended solids. This makes no sense to me. Furthermore a reef needs 1-2ppm Mg for every 20 ppm calcium dosed.

The amount of Mg provided by kalk+2 is not meaningful.

Ok, glad I got that off my chest.

And I just got the biggest bag of Kalk+2 .... Crap