Magnesium dropping fast

[Walla2GSP]

So as I bring my tank back from the dead, I've been dosing Mag to keep the levels up so I can maintain a little higher Alk and Ca. I didn't have a working magnesium test so I just got a new Salifert 2 weeks ago and started testing. My initial test was 1350 so I upped dosing a little as I was shooting for 1500, a few days later it was 1320 so I upped it a little more, then tested a couple days ago it was 1200 so I put in the max recommended dose and tested this morning and got 1050. Now, this morning's may be off and I'll doublecheck a little later, but it appears my Mag has dropped 200-300 ppm over the course of two weeks. Shouldn't it have gone up slightly with dosing? Alk and Ca have been staying pretty steady, so i haven't had to worry about them other than the occasionally test to make sure they aren't being too effected my carbon and magnesium testing. I'm using Kent tech-M.

pH: 8.2
kH: 13
Ca: 440
Mag: 1200-1050

Has anyone dealt with this? Am I missing something?

 

[thegrun]

Are you sure you are following the testing directions exactly? If you don't swirl the solution for the recommended duration before adding the titration solution it will give you inaccurate results. Also are you sure you are dosing the correct amount of the tech-M? It takes a lot more magnesium solution than calcium or alkalinity solutions to raise your magnesium levels. It's rare to see such large drops in magnesium, I suspect the problem is in testing or dosing. On a side note unless you are battling Bryopsis, 1350 ppm is the recommended magnesium level, 1500 is a bit high.

 

[mcgyvr]

What are your target cal/alk numbers?
13 is too high for alk..

Most are finding its better to run alk at the lower range (8-9) vs high range (10-11)..

 

[Sk8r]

Get an egg timer and use it to count the seconds of 'swirl' needed. Voice-counting is not that accurate unless you're real used to it. THis is the one test that requires precision. I frequently tuck the vial I'm swirling into my little finger's hold while I proceed to open the next bottle, fill the syringe, etc: it's just the gentle motion that step needs. Also: the BOTTOM of the plunger should rest on the zero line for a fill of the syringe.

 

[Walla2GSP]

Are you sure you are following the testing directions exactly? If you don't swirl the solution for the recommended duration before adding the titration solution it will give you inaccurate results. Also are you sure you are dosing the correct amount of the tech-M? It takes a lot more magnesium solution than calcium or alkalinity solutions to raise your magnesium levels. It's rare to see such large drops in magnesium, I suspect the problem is in testing or dosing. On a side note unless you are battling Bryopsis, 1350 ppm is the recommended magnesium level, 1500 is a bit high.

I treat it like any other Chemical titration and stay fairly precise with my procedures. I'm not sure I'm dosing the correct amount, I started out dosing a little to bring it up slowly because I wasn't in a hurry, but now with it dropping faster than calcium and ALK, I guess I'll have to mix up a big batch of Magnesium and dose it at regular intervals which kinda contradicts my understanding of how Ca, ALk, and mag are related in the aquarium.

What are your target cal/alk numbers?
13 is too high for alk....

Alk I am shooting for 9-10 and Calcium I am shooting for 450, but I always struggle to keep Alk below 12 without dosing Muriatic acid daily, which I would rather not do. Typically if i can get calcium and magnesium up slightly ALK will come down slightly, which was my other reason for wanting to dose mag.

 

[Walla2GSP]

I jsut did a second test because I suspected my testing this morning was off and got 1200, so it hasn't gone up or down in the last 72 hrs .

 

[Sk8r]

Well, you may be into the 'ask the Reef Chemistry' forum territory with this one if your procedures are spot-on.