Magnesium?

[Reefist]

I have had years of Mg level problems. I've tried to raise levels adding magnesim-P with adverse reactions to corals losing quite a few. Only guessing that by the proximity of the adding times. So I added Neo Mag to my Ca reactor and that doesn't work either. Effluent is at 1100ppm Mg which is what the tank is. When I add Magnesium to the sump in high flow area there is no pH swing since I add it near the probe( yes always check that probe) the Mg level just plummets to below 1000 and usually the the next day I see SPS stress .I even tried dripping it. So now (2 months)I just started adding magnesium-P to the makeup water and nothing changes. Any thoughts here on how Mg precipitating ? I wouldn't care about the levels since my Alk is 8.0dkh and CA420 but there is very slow growth on most of my corals except Montiporas and Bali slimer. Actually alot perish over time. Phos level .04.
Any thoughts
Tom

 

[LetoII]

I use the Seachem MG supplement (in addition to reef calcium and reef builder carbonate supplement) I always find its hard to keep the MG up but I've added spoonfuls of seachems's MG dissolved into tank water into a 3gal pico with no ill effects...

The first time I used MG was to try to kill GHA in my red sea max... it didn't work but what did happen was an explosion of coraline when the level was over 1500. Good luck!

 

[Monkeyfish]

What salt do you use? After I switched from IO to ESV my levels were better across the board and more stable.

 

[Reefist]

I/O Reef Crystals. The point I'm trying to understand how do the readings go lower when I add Mg.If my ph was spiking I'd under stand but they are not . I've bought a new probe recalibrated tens of times. So where is it going? and why the lower readings. If I leave it alone it will come back to 1100. And I have 3 Mg test kits . The last 2 weeks old.I don't know chemistry so I don't get it. What else can preciptate Mg besides pH?
Thanks
Tom

 

[bertoni]

There's nothing that can lower the magnesium level appreciably in saltwater like that except a very high pH or a lot of time.

Do you have the measurements you made and do you know the exact amount of supplement that you added? You might want to do some controlled experiments with a 5g container of fresh saltwater, too. Like measure the magnesium level, add a controlled amount of supplement (say 100 ppm), and then remeasure the magnesium. You could try the same experiment with epsom salts, which are cheap, as a sanity check on the supplement you're using.

This calculator should help with doses:

http://reef.diesyst.com/chemcalc/chemcalc.html