Another question if you don't mind regarding my low tec plant.
Melbourne's water is 3 degrees GH according to my test kit.
I am happy with these levels for both flora and fauna in my tank.
With time (as i don't anticipate doing water changes) GH levels will drop.
I will then need to supplement GH levels.
My understanding is that 0.79g CaCl2+0.33gMgSO4=1 degree GH

This formula gives me a ratio of Ca/Mg of 7:3.

ie. I will need to add 11.85g of CaCl2 to obtain a 0.7 degree increase in GH (or 12.6ppm) and
4.95g of MgSO4 to get a rise of 0.3 degrees in GH (or5.4ppm) in 150 gallons of water.

Is this correct if i want to increase GH by 1 degree?

I note in the fertilator , if i key in 11.85g CaCl2 in 150 gallons water my Ca++ reading is only 7.74ppm and for MgSO4 4.95g gives 0.86ppm of Mg++.

My understanding is that GH test kits measure in CaCo3??
To obtain the actual Ca++ and Mg ++ in ppm you need to divide Ca by 2.5 and Mg by 4.1. Is this correct?

LAKA