Correction to magnesium supplement receipe

[Greg Hiller]

Thanks to Ed P. for catching an error I made in the large volume prep of this supplement.

The first (smaller prep) measurement is correct. The second measurement should be:

7.3 lbs MgCl2.6H2O
1.25 lbs MgSO4.7H2O (Epsom salts)
plus enough DI water to make 5 gallons

It looks like the mistake I made made no difference in the Ratio of the two chemicals to each other, it's just that the solution would be much less concentrated than it could be.

 

[nunofs]

Greg: do you happen to know how that translates into cups or other household measure? The reason I'm asking is that I don't have a precision scale to weigh the chemicals (my kitchen scale is so bad that it's probably got a 1/2 lb accuracy...) and am afraid of creating an imbalanced solution.

Thanks,
Nuno

 

[Greg Hiller]

Nuno,

I don't remember off hand. You can pick up a kitchen type balance at the supermarket for probably $7.

 

[reefnroll]

Greg/Ed -
Thanks so much for this correction. I had been dosing epsom salts for a year before switching to the Mag chloride/sulfate mix... but I couldn't understand why it was taking so much of the new mix to keep my levels up (compared to what I was using with the straight epsoms). I was thrown off at having just doubled the volume of my system... but not understanding why doubling what had been my old dosage wasn't coming anywhere near keeping up!

Nuno -
I just measured the stuff out so that I culd mark a container to use with the levels I want to mix for each batch. Right now I'm only mixing 1 gallon at a time, which translates roughly to 1.5 lbs. of Mag chloride and .25 lbs of Mag sulfate per gallon. That works out to about 2 cups of Mag chloride and about 1/3 cup of Mag sulfate per one gallon of DI water. For my 300 gallons of water, that gallon should keeps my levels in check for about a month (or so)...FYI. Hope that helps.

bec

 

[nunofs]

Bec, it sure helps, thanks! Maybe this weekend I'll dose magnesium (yes, I still haven't bought a scale, so I'll try the 2 cups + 1/3 cup recipe).

Nuno

 

[reefnroll]

Based on the revised numbers at the top of the thread, it should be close enough... about 6 to 1 ratio. Nothing to be concerned about if its a little bit off. It takes what seems like a ton of this stuff to make a dent in the levels... so overdosing would be tough.

b

 

[ReeferMedic]

How much amonia does mag contain? Just something to keep in mind while dosing.......

 

[Greg Hiller]

Randy asked the same question on the old thread, and a valid concern.

Here was my response:

So, I preped some of the supplement last night using the MgCl2 from the new bags. I diluted the stuff out (necessary to run on this instrument) and ran it on an analytical instrument here at work and the ammonia level came out pretty close to the lower limit of detection of the instrument. After a quick calculation I come up with about 60 ppm ammonia (NH3) maximum in the concentrated supplement. If we were to use the supplement as I outlined above to increase a tank about 100 ppm Mg per day then you would be adding a maximum of 0.15 ppm NH3 to your tanks water with each dose. In a functional reef tank this is not a level I would be particularly concerned about. I would imagine this would be processed by the nitrifying bacteria in your tank within a few hours at most.

So, I think we are fine on the ammonia question.

One thing to note, for the supplement I preped I used lab grade magnesium sulfate (along with the magnesium chloride bags we received) rather than Epsom salts as I didn't want any ammonia in the Epsom salts to confound the results. I don't think that there is likely to be a lot of ammonia in Epsom salts since it is USP grade, but YMMV (your mileage may vary)!

 

[ReeferMedic]

Thanks Greg, just something I was curious about.....