Brightwell kalk with magnesium

[KevinC]

Having some trouble understanding how to use kalk and magnesium…

I have read that magnesium shouldn’t be mixed with high PH additives since it would precipitates, hence my understanding is that you cannot add magnesium directly to kalk solution for drips.

So how is product like brightwell able to incorporate magnesium into their kalk+2?

(2 being strontium and magnesium)

 

[Randy Holmes-Farley Verified Community Expert]

Having some trouble understanding how to use kalk and magnesium…

I have read that magnesium shouldn’t be mixed with high PH additives since it would precipitates, hence my understanding is that you cannot add magnesium directly to kalk solution for drips.

So how is product like brightwell able to incorporate magnesium into their kalk+2?

(2 being strontium and magnesium)

It's not. It's a crazy bad product claim.

Here's a copy and paste from older threads:

Magnesium is not soluble in limewater, so it will just sit on the bottom and worse, the amount present in kalk+2 is not nearly enough to meet the demand for magnesium, and far worse yet, is LESS than is present in many bulk brands of calcium hydroxide as an impurity.

Here's the Brightwell kalk+2 claim:

http://brightwellaquatics.com/products/kalk2t.php

Guaranteed Analysis
Calcium (min) 54.20% (542,000 ppm), Strontium (min) 1.00% (10,000 ppm), Magnesium (min) 0.15% (1,500 ppm)

So that is a ratio of magnesium to calcium of 1:361.

I show in this article that bulk calcium oxide (dried calcium hydroxide) has more magnesium as an impurity (1:263) and that in the actual limewater, the magnesium ratio does not exceed 1:36,000, with the remainder ending up undissolved on the bottom.

Magnesium and Strontium in Limewater

Aquarium Chemistry: Magnesium And Strontium In Limewater​

Because of a potential imbalance between the amount of magnesium and strontium used by corals, and the amount delivered by limewater, using limewater can potentially lead to depletion of both ions in aquaria.


I show in this article that a typical coral or coralline aglae incorporation rate is 0.1 to 4%by weight, for a ratio of about 1:400 to 1:10.

https://reefs.com/magazine/aquarium-chemistry-magnesium-in-reef-aquaria/

 

[besskurz]

I got lots of softies and low reading of MG and I thought kalk+2 would help me.
Tested after months, mg is still low.
What a bad product.

I'm gonna dose mg alone and that's it.

 

[Randy Holmes-Farley Verified Community Expert]

I got lots of softies and low reading of MG and I thought kalk+2 would help me.
Tested after months, mg is still low.
What a bad product.

I'm gonna dose mg alone and that's it.

True, it’s not ever a suitable way to add magnesium.

 

[besskurz]

True, it’s not ever a suitable way to add magnesium.

Yeah that's truly deceiving.

Probably that's why all corals are kinda stagnated and an acan ultra is not puffy anymore.

Thanks for all the knowledge shared @Randy Holmes-Farley