Can anyone explain rotala butterfly and GH dosing?

[Pepere]

I was advised to ensure dosing of 35 ppm calcium and 5ppm Mg…. Of course I have also had people tell me The Ca to Mg ratio should be between 3-1 to 4-1…. But regardless, though feel free to offer insight on that as well..



35 ppm calcium yields 4.9 degrees of GH.



5 ppm Mg yields 1.15 degrees of GH…


But…

Degree hardness to Parts per million converter (°dH to ppm) - MathDA.com

Degree hardness (°dH) to Parts per million (ppm) converter. Degree hardness to Parts per million converter. How to convert Degree hardness (°dH) to Parts per million (ppm)

mathda.com

This page insists that 1 degree of hardness is the same as 17.85 ppm…


But, 35 ppm Ca, and 5 ppm Mg would be 40 ppm…. And if 17.85 ppm equals 1 degree of hardness… 40/17.85=2.241 degrees of hardness…

I freely admit I might be missing something… can anyone enlighten me? I just dont understand…

 

[SkaleyAquatics]

Not really sure about mathDA but I have tested gH after water changes and it comes very close to the combined gH of Ca and Mg on rotalabutterfly.

 

[vinzphua]

When we say 1ppm of GH, we mean equivalent of 1ppm of CaCO3. 1dGH is equivalent to 17.86 ppm of CaCO3.

Don't worry about the ppm of GH, use dGH. Just dose the ppm of Ca and ppm of Mg you need.

 

[vinzphua]

But let's say you dose a certain ppm of Ca and Mg, you can calculate how much GH it should raise in dGH and if you measured it, it will match. Most people don't use ppm of CaCO3 when talking about GH levels... It is confusing as you experienced.