How much Magnesium to dose?
 

Work has slowed me down previously but now I have the time to start setting up the dosing regiment.

Currently my levels are low, and I realize that it is best to raise Mg first, before tackling the others.

Recently I purchased bulk magnesium from reefsupplies.ca, the magnesium chloride/sulfate mix:

http://www.reefsupplies.ca/online-st...-1-Gallon.html

At a current level of 1150ppm; I would like to raise/keep it at 1350ppm. The problem is, the product didn't come with a chart on the proper level/dosage. There's two bags of stuff, one MgCl and the other MgSO. It says the two bags make 1 gallon of solution but that doesn't really help how much volume I should dose? It does say it's 5 part MgCl and 3 part MgSO.

Is there a proper online calculator which will allow me to see how much to dose? Thanks!

(total water volume is ~200g)

I use the BRS calculator on their site. Works for me. I mix BRS mgcl with Walmart Epsom salts. Saves some money in the end, and mixes very good.

Not sure if it helps but i believe bulk reef supply may have an online calculator for that. It will be suited to their product but may give you a general target

The thing with the BRS calculator is, they have dosage for MgCl, MgSO, and then a "BRS Mix Solution" which I cannot verify is the same product as the stuff I got from reefsupplies, so at the moment I am stuck.

That's the same thing Brian, just use that one. All the chemicals are the same, no matter where they come from. Just the grade is different.

To be clear... Use the mix solution one.

I don't disagree. It's just that I am unsure if the reefsupplies (which is 5 part MgCl, 3 part MgSO) is the same as the BRS Mg Mix (which doesn't say anything about the ratio of the mix, which if different from the reefsupplies one, then it would throw the calculator off).

I think that the mix one is just the 5 part / 3 part pre measured out.

Yup. Both have the same mix ratio.

BRS mixing directions for two part
 

5 cups magnesium chloride & 3 cups magnesium sulfate in one gallon fill with rodi

Yep BRS is the same mix as Warren and Dave said , 5 / 3 mix

Thanks guys for the confirmation.

It calculated that to raise 100ppm of 200ga total volume, I'll need 1612.9 mL. Does that sound like a sensible number? That's like almost 1/2 of the whole mixture lol.

That sounds about right. Dump half of it in and test in a few hours.

It takes a lot of mag solution to raise the numbers , much more compared to Alk/cal

Use the following calculator:
http://reef.diesyst.com/chemcalc/chemcalc.html

George beat me to it. But you might also find this article on DIY Magnesium supplementing useful. http://reefkeeping.com/issues/2006-07/rhf/

Will add 750mL tonight (half of the recommended dosage) and check back with a Mg test tomorrow morning. My levels are all pretty low since I haven't dosed at all since the tank began 3 months ago, all I've done are simple 25% monthly WCs. Still working on getting N and P down, Foz-down since last month and vinegar dosing recently.

What salt you using?

In the interest of you becoming a mod, I shall leave this information secret. :lol:

Nah but for reals I'm just using regular IO.:wink:

Ya, don't tell them anything, they'll use it against you one day!!

I'm so tired right now, that I don't even have any smart a$$ comments to hurl at you guys.

IO mixes at around 1200... so 1150 with not dosing sounds about right. Ever thought about changing salt? You should start a poll on peoples favourite salt. :lol:

Gimme a moment, let me go look at my batch numbers first and I'll get back to you :wink:

Not for a while though, I picked up two 200g boxes a while back and that will last me some time.

Tested today's levels, actually slightly overshot, currently Mg at 1400ppm. (aiming for 1350ppm) I think I overestimated my total water volume.

Next WC in a week and gradual lowering should take care of that.

Now aiming to get my Alk back up, it's at 7 dkh. Will hope to get that around 8.5 then I will get the Ca up, but not before a lights-out soon, as I'm battling some cyano problems. I have Chemi-Clean but I'm saving that as my last option.

Stable alkalinity will help w cyano.

Should I let it stay at 7.0 for now then?

From what I understand, you should try to aim for 8. Gives you a bit more room for swings. Currently I am running between 7.3 and 8, still trying to balance it out by tweaking the doser... 7 weeks on.

7 is a bit low unless you're doing full Zeovit or some such thing. Figure out where you want it, get it there, and get it stable.

I raised it from 6 to 7 two days ago, and my pH climbed to an alarmingly high number, only steadily lowering since last night to a more acceptable reading. Should I continue to raise Alk slowly to avoid a pH spike? I was told that 8.5 is the number I should shoot for, yes?

What type of salt are you using for water changes? May be able to boost the magnesium by using RC instead of IO for instance instead of dosing.