High mag level too high?

[hobbby3]

My mag levels appear to be going higher and higher. When I first started testing it was in the mid 1300s now I'm up around 1500. At what point does mag become dangerous? Why would it increase I don't dose anything and use RO/DI water tds is currently 3. Maybe I just need more coral to suck up the nutrients... ? :)

I use Kent reef salt
testing with Red sea kit
Alk = 9.2
Calc = 500
Mag 1500
Specific gravity = 1.024
Temp 79.5
ammonia 0
nitrite 0
nitrate 0
phosphate 0

[bertoni]

I would measure the magnesium in some freshly-mixed saltwater. The magnesium level should not rise if nothing's being dosed and the salt is okay. Getting a second opinion on the test kit might be useful, too.

[hobbby3]

I would measure the magnesium in some freshly-mixed saltwater. The magnesium level should not rise if nothing's being dosed and the salt is okay. Getting a second opinion on the test kit might be useful, too.

Thanks Bertoni I'll do that. Should I test my Ro/DI water mag level before mixing salt also or would that just be a waste?

I used reefrock dry rock wonder if I could be leaching mag

Do you know at what point it becomes dangerous for fish and coral (sps, lps)

[bertoni]

I don't think measuring the RO/DI water will work at all. :) It had better be so close to zero as makes no difference, in any case.

[Nicodemus85]

Not too much to worry about with your Fish and Corals and the Mg levels, at least not at 1500. The only consequence will be an inorganic MgCO3 precipitate that is basically like sand. But if your Alk < 10, then this probably won't happen unless your DIC is really low.
Also, a 200ppm change is not a whole lot given the precision of the test kits. Simply testing at different times in the day and thus at different points in your daily evaporation process could account for some difference as well.

Your LR or sand could be leaching Mg. What is your pH? On real coral reefs, when the pH drops at night to 7.8, the sand and LR will naturally "leach" Mg and Ca. Aside from freshwater input, this is how reefs naturally obtain these cations. Also, how deep is your sandbed? A really deep sand bed can have a good deal of anaerobic metabolism in the deeper parts, creating a low pH environment which will leach out Mg and Ca as well. Just some thoughts.... :)

[hobbby3]

I don't think measuring the RO/DI water will work at all. :) It had better be so close to zero as makes no difference, in any case.

haha indeed!

[hobbby3]

Not too much to worry about with your Fish and Corals and the Mg levels, at least not at 1500. The only consequence will be an inorganic MgCO3 precipitate that is basically like sand. But if your Alk < 10, then this probably won't happen unless your DIC is really low.
Also, a 200ppm change is not a whole lot given the precision of the test kits. Simply testing at different times in the day and thus at different points in your daily evaporation process could account for some difference as well.

Your LR or sand could be leaching Mg. What is your pH? On real coral reefs, when the pH drops at night to 7.8, the sand and LR will naturally "leach" Mg and Ca. Aside from freshwater input, this is how reefs naturally obtain these cations. Also, how deep is your sandbed? A really deep sand bed can have a good deal of anaerobic metabolism in the deeper parts, creating a low pH environment which will leach out Mg and Ca as well. Just some thoughts.... :)

Facinating!
Alk is 9.4
My PH is 8.2 tested in the evening just before lights out.
Sand is 2-3 inches
The live rock and sand must be the culprit then?
Do they eventually stop leaching or do I seriously just need more coral to use it up?

[reefling]

I would not worry about it. People were raising alk to 2000 for bryopsis, and their corals are fine. Your salt is 1500 mag. That is why your tank is at that level. The sand and rock can only Leach so much. Soon coralline and corals will use enough that you have lower than the base salt amount.

[mr_bigl]

One thing no one mentioned was making sure your test vial is clean. Just rinsing with tap water is not good enough. Some titrate and other stuff will stay behind Thus giving u inaccurate test. Fill it with hydrogen peroxide shake it up, rinse with rodi water then dry it out then test. You'll start getting consistant numbers . Then you'll know for sure if its moving or user error. Also make sure your kit is up to date.

[tmz]

At 8.2ph , I don't think sand and rock are dissolving and/or leaching calcium and magnesium. 1500ppm is not a big worry in any case. I'd look toward the salt mix or a testing issue .

[bertoni]

I agree that the live rock and sand can't be leaching magnesium. I suspect that either the salt is a bit high in magnesium or the kit is a bit off. As long as the animals are doing well, I wouldn't worry.