Calcium level of saturated limewater

[pmcustom]

What is the calcium level of saturated limewater at room temp, 1.026sg, or basically standard conditions? I'm not sure I'm adding enough kalk to saturate the RO. Thanks.

[Randy Holmes-Farley]

It is about 816 ppm at 25 deg C.

It is easier to measure limewater saturation via conductivity (about 10.3 mS/cm at 25 deg C).

One can also get a crude measure by pH.

It is also about 41 meq/L in alkalinity at 25 deg C.

[pmcustom]

Thank you!

[Randy Holmes-Farley]

You're welcome.

Happy Reefing. :)

[Hobster]

what would that come out to for say adding 1gal to 50 gal of water. How much would the Ca and Alk be raised?

[Randy Holmes-Farley]

That would be a 50 fold dilution, so you'd add 1/50 of the amount present, or about 816/16 ppm calcium and 41 meq/l/50 = 0.8 meq/l (2.3 dKH).

[Hobster]

Thank you.

So the 816ppm Ca and 41 meq/l is the amount in each gal of solution?

[Randy Holmes-Farley]

Yes. It is also the amount in a million gallons of solution. :D

OK, seriously now, those units (ppm and meq/L) are amount per unit volume (well, OK, ppm is not strictly amount per unit volume, but it is close).

So if you have X of something in one solution, and dilute it by 50, then you have X/50 in the new solution. Strictly, it was diluted 1:51, not 1:50, but that is also a minor issue.

Does that make sense?

[Hobster]

yes, I think so.:)

Not that I would ,but if I did add 5 gal to 50 gal tank

816/50=16 x 5=80 ppm increase in Ca ?

for 100 gal:

816/100=8 x5=40 ppm Ca.

Not accounting for the rounding or the exact ratio of 1:55 or 1:105

yay or nay?:lol:

[Randy Holmes-Farley]

yay :)

[Hobster]

Thanks :thumbsup:

[Randy Holmes-Farley]

You're welcome. :)

[Randy Holmes-Farley]

One clarification to make sure we all agree about what I thought was clear, but Bojan correctly pointed out is not:

If you add 50 gallons of 400 ppm Ca++ tank water to 5 gallons of 820 ppm Ca++ limewater, the resulting calcium concentration is raised by 38 ppm, ot 438 ppm. [ (50 x 400) + (5 x 820) ] / 55

If you then allow that to evaporate back to the original 50 gallons, the concentration rises to 482 ppm.

So the 1/55 correction vs 1/50 correction is rather significant in thinking about how much the calcium rises.