Tropic Marin All for reef dosing calculations

[Randy Holmes-Farley]

@Randy Holmes-Farley in the past you've recommended 10% dosing mg to calcium. Based on those weights AFR contains 5% - is this too low in your opinion?

The magnesium to calcium demand ratio will depend on exactly what is using the calcium. Coralline algae has about the highest ratio, and is about the 10%. Some corals are much lower. 10% would be best for a tank where coralline is a lot of the demand,. 5% might be better when it is a small part of the demand.


In either case, water changes, very high levels in most salt mixes, and the very slow natural movement of magnesium make the differences typically minor.

My RMM thread says:

ANY time that you add calcium, add 5-10% as much magnesium (so for 10 ppm calcium, add 0.5 - 1 ppm magnesium). If coralline is the main user of alk in your tank, use the 10%, if corals are, use 5%. A lot of products, like commercial two parts, AFR, CaCO3/CO2 reactors with suitable media, and my DIY two part systems all add magnesium for you, without measurement.

Just say NO to magnesium testing: RMM is born

OK, this thread has been many years in the making, and I'm posting it here since folks in the chem forum are probably already tired of all the threads relating to problematic magnesium testing. I'm going to propose a method, let's call it the Randy Magnesium Method, or RMM for short. All good...

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