Neptune Aquatics

Dosing Magnesium, am I doing it right?

badbread

badbread

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So, I picked up a Magnesium test kit tonight and decided to test my salt mix magnesium levels. I've read that some salts have low levels of magnesium so I thought I would test.

The vital info:
Using a Red Sea magnesium test kit
Water change water is at about 77 degrees at 1.024 salinity
Using Coralife Scientific Grade Marine Salt

I tested the water twice with the same result both times:

For those familiar with the Red Sea test kit, this is how I performed the test:

  • [li] Fill the ml syringe with 1ml of reagent C (I filled until the liquid was at 1ml, not the plunger)[/li]
    [li] Add 0.4ml of reagent C to the test tube while mixing gently (ok, did that)[/li]
    [li] Add 1 drop of reagent, mix gently, wait 2 seconds to see if the color changes[/li]
    [li] Step 9: Note the amount of reagent C used. Reagent used (ml) = 1 - regent left in syringe[/li]

According to a reefkeeping magazine article the target level for Magnesium is between 1250-1350 or 1200 - 1400. I guess my mix is not off by that much but I bought the kit and a bottle of Kent Tech M magnesium so I might as well bring the level up.

So I used 0.56ml of reagent.

According to the test kit instructions Magnesium concentration (ppm) = Amount of reagent used (ml) x 2000

So, 0.56ml x 2000 = 1120ppm Magnesium

The Tech M Magnesium directions say:
1ml = 18.3ppm in 1 gallon of water
15ml x 18.3ppm = 274.5ppm
274.5ppm + 1120ppm = 1394.5ppm

But that is only for 1 gallon of water.

If that is correct then I need to multiply the 15ml of Tech M by about 4.5 for the 4.5 gallons of water in the bucket right?
15ml x 4.5 = 67.5ml to get my level up to 1394.5ppm

That seems like an awful lot of product compared to other things we dose in our systems. Does this sound right? Are magnesium additives super diluted or something?
 
So I double checked with that online reef calculator and my math was about 7ml off from that site. I dosed and tested and my Mag levels were at about 1390.

Is it safe to assume that every batch I mix up in this bag will have about the same level of Magnesium? I mix the salt mix bag up well before opening every time.

Thanks,
Jay
 
Salts generally are pretty consistent, most of them are mixed at the same facility to the manufacturers specs. Notice I said generally, I just bought a bucket of SeaChem reef that tested off the charts for calcium and would have precipitate no matter how long I mixed it. I'm afraid to even mention Reef Crystals that horse has been beat to death. It's a good idea to test your make up water before changing out when using a new container.

BTW, it is friggin crazy how much mag you need to boost your levels, there's a lot of that stuff in saltwater water :D
 
I'm on my second bucket of SeaChem Reef after using only Tropic Marin Pro for a few years. The precipitate for me only clears up after two full days in my big Brute with a strong PH. I also have to net a bunch of crap that floats to the surface.
 
I've been using the SeaChem Reef for over a year and never had trouble mixing on site. That is very important to me, I need the salt in solution within 1/2 hr maximum, the last bucket I bought didn't do that and it REALLY made a headache for me. I had to bottle up the cloudy mix, then drive from HMB to San Mateo and back with a bag of IO, it was a real drag.
 
Ya... I've never had that problem with IO or Tropic Marin... I have a new bucket of SeaChem Reef I'm going to try this weekend and I'm hoping it does not have the same problem... probably will.
 
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