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yraveh
02/09/2009, 05:19 PM
In Recipe #2, Part 3A, Randy outline the proportion of MgCl and Mg-sulfate to mix for the maintenance mag supplementation.
Where can I find the detailed calculation why this is the correct ratio of sulfate versus chloride?

HighlandReefer
02/09/2009, 05:22 PM
Do-It-Yourself Magnesium Supplements for the Reef Aquarium
http://reefkeeping.com/issues/2006-07/rhf/index.php

Randy Holmes-Farley
02/09/2009, 06:34 PM
For the DIY two part recipe, the results of the calculations are here:

http://reefkeeping.com/issues/2006-02/rhf/index.php#19

Are you asking exactly how I did it?

HighlandReefer
02/09/2009, 06:48 PM
Sorry. :)

I am still confused as to why there are two different ratios of chloride to sulfate? From what I understand, one ratio is for boosting your salt mix and the other is for supplementing. I don't understand why there is a difference. :confused:

yraveh
02/10/2009, 12:42 AM
<a href=showthread.php?s=&postid=14357605#post14357605 target=_blank>Originally posted</a> by Randy Holmes-Farley
Are you asking exactly how I did it?
Yes. I am looking for the data from which you derived the molar ratio of consumption (precipitation) of sulfate and Cl anions.

Randy Holmes-Farley
02/10/2009, 06:56 AM
Ah, there is no consumption. The goal is to just add chloride and sulfate so that overall what you added you matches the chloride to sulfate ratio in seawater.

With just the mag supplement alone (MgCl2 + MgSO4), that gets to the 10:1 and is simple to calculate.

When you are using calcium chloride as part of a two part, you also need to account for the chloride from the calcium chloride, hence a lower ratio of MgCl2 to MgSO4 (5:3)

Make sense?

HighlandReefer
02/10/2009, 07:07 AM
OK, if I am bumping up IO mix with calcium chloride (MagFlakes) along with bumping up magesium. Does this mean I use the 5:3 ratio?

Randy Holmes-Farley
02/10/2009, 07:30 AM
I'd use 10:1 in that case. In the two part that gives 5:3 you are adding a lot more calcium than magnesium, but to IO you are probably adding more magnesium than calcium, so the input from calcium chloride is low.

I actually use mag flake alone most of the time, and about 10% of the time use Epsom salt alone to balance it. Not perfect, but simple.

HighlandReefer
02/10/2009, 07:33 AM
Thanks Randy, for clearing my confusion. :D

yraveh
02/10/2009, 09:42 AM
<a href=showthread.php?s=&postid=14360995#post14360995 target=_blank>Originally posted</a> by Randy Holmes-Farley
Ah, there is no consumption. The goal is to just add chloride and sulfate so that overall what you added you matches the chloride to sulfate ratio in seawater.

With just the mag supplement alone (MgCl2 + MgSO4), that gets to the 10:1 and is simple to calculate.
If I understood correctly, U R saying that while supplementing Mg , the anions cl and sulfate accumulate and their concentration increase. U wrote a recipe designed so that their ratio is preserved even if the absolute concentrations increase.

If that's indeed the case I am not sure that this recipe makes sense.
lets assume for the sake of the argument that in saltwater tank hyper- Cl is more toxic than hyper- sulfate. Then I would prefer to supplement Mg with epsom. even if that means abnormal ratio of the 2 anions.
a clinical corrolary, for example plasma ratio of Na To K is 140/4.5. If i was forced to induce both hypernatremia and hyperkalemia, I would prefer to increase the NA over the K thus ignoring the ratio. That is of course because hyperkalemia is much more dangerous.

Randy Holmes-Farley
02/10/2009, 12:52 PM
If I understood correctly, U R saying that while supplementing Mg , the anions cl and sulfate accumulate and their concentration increase. U wrote a recipe designed so that their ratio is preserved even if the absolute concentrations increase.

Yes.

Don't forget the cap that salinity monitoring puts on the rise in ions. :)


I have no reason to believe that you want to change the ratio of chloride to sulfate. You keep the total ions in line by salinity measurements and adjustments. If salinity is correct, and the ratio is correct, there cannot be any significant excess chloride or sulfate since together they account for nearly all of the anions present. :)