rota.la MgSO4 GH wrong? - The Planted Tank Forum
 
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post #1 of 1 (permalink) Old 03-23-2015, 05:53 AM Thread Starter
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rota.la MgSO4 GH wrong?

http://rota.la and http://calc.petalphile.com are giving unexpected results for MgSO4 dGH.

CaCO3 GH
= Ca GH + Mg GH
= [Ca] * CaCO3/Ca + [Mg] * CaCO3/Mg
= [Ca] * 100.0857 / 40.078 + [Mg] * 100.0857 / 24.305
= [Ca] * 2.497 + [Mg] * 4.118

1 dGH = 10 ppm CaO = 10/56.077*100.0857 = 17.848 ppm CaCO3

dGH = ([Ca] * 2.497 + [Mg] * 4.118) / 17.848

(http://en.wikipedia.org/wiki/Hard_water says 2.5Ca + 4.1Mg)

http://rota.la (10 gal, DIY, {Stuff}, Dry dose, result of dose, 10g, 3 digits):

10g CaSO4.2H2O in 10 gal yield 61.494 ppm Ca, 8.589 dGH
check: 61.494 * 2.497 / 17.848 = 8.603. ok for [Ca] to dGH

10g Mg(NO3)2.6H2O in 10 gal yield 25.042 ppm Mg, 5.736 dGH
check: 25.042 * 4.118 / 17.848 = 5.778. ok for [Mg] to dGH

but:

10g MgSO4.7H2O in 10 gal yield 26.051 ppm Mg, 1.459 dGH
check: 26.051 * 4.118 / 17.848 = 6.011. oops.

My sanity check is nearly identical [Mg] (25ppm, 26ppm) and 0 ppm Ca should yield same dGH, but they are not.

[Contact on rota.la yields "503 Service Unavailable"]
justin12 is offline  
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