1680 Magnesium

[whotzler]

Yep Just like the title says, I somehow got mag up to 1680. I have been adding without testing for the last couple months.. Yes that is always a good idea... So I tested today, twice with the same result.. Using salifert test. I still did not believe it, so mixed up some fresh reef crystals at .026 tested and got 1400 just as it should. Based on this I do believe the 1680 is accurate. Also I believe it has been this high for a few weeks if not a month already.

My tank is 120 gals, plump full of colonies, mixed reef, mostly acros and monties. Salinity at .025 DKH 8 ish calcium 420. Tank consumes a gallon and a half of full saturated kalk with the addition of .5 dkh of soda ash per day. I add supplement calcium and mag when needed, and apparently when not needed also. Would it be a good idea to just ride this out? I heard of high but 1680 is HIGH.

I have a fist size green slimmer that mysteriously no longer has any polyp extension. I first noticed this about a month ago and may or may not be related, but other than that all corals seem fine. My thought was to do at least a 30% water change and bring it closer to upper 1500, and let it ride. Anyone have experience with this high mag?

 

[vegamedic]

Personally I'd just let it ride. I've purposely jacked my mag up that high before and didn't see any problems. I don't believe high mag is known to have any deleterious effect

 

[Bob Weigant]

I know people who maintain 1600. I keep mine around 1500- 1600

 

[Swoody]

Interesting to read since I just recently read somewhere else on here that Mg at or over 1500 can or does cause stn and or rtn... and since reading that have been slowly letting mine lower from a little over 1500 by stopping the dose since I experienced some stn’ing in my tank... going to let mine get to 1450-1425 and see how thinks do there.

 

[vegamedic]

Interesting to read since I just recently read somewhere else on here that Mg at or over 1500 can or does cause stn and or rtn... and since reading that have been slowly letting mine lower from a little over 1500 by stopping the dose since I experienced some stn’ing in my tank... going to let mine get to 1450-1425 and see how thinks do there.

I'd be interested to hear if letting your mag drop helps with your STN. When my mag was 1500+ I didn't have SPS in the tank

 

[chipmunkofdoom2]

Yep Just like the title says, I somehow got mag up to 1680. I have been adding without testing for the last couple months.. Yes that is always a good idea... So I tested today, twice with the same result.. Using salifert test. I still did not believe it, so mixed up some fresh reef crystals at .026 tested and got 1400 just as it should. Based on this I do believe the 1680 is accurate. Also I believe it has been this high for a few weeks if not a month already.

My tank is 120 gals, plump full of colonies, mixed reef, mostly acros and monties. Salinity at .025 DKH 8 ish calcium 420. Tank consumes a gallon and a half of full saturated kalk with the addition of .5 dkh of soda ash per day. I add supplement calcium and mag when needed, and apparently when not needed also. Would it be a good idea to just ride this out? I heard of high but 1680 is HIGH.

I have a fist size green slimmer that mysteriously no longer has any polyp extension. I first noticed this about a month ago and may or may not be related, but other than that all corals seem fine. My thought was to do at least a 30% water change and bring it closer to upper 1500, and let it ride. Anyone have experience with this high mag?

A 30% water change will not bring the Mg to anywhere near 1,500 ppm in your situation. If your newly mixed saltwater has Mg close to 1,400 ppm, a 30% water change would only drop your Mg to around 1,600 ppm. You would need to do a 65% change to get your Mg to 1,500.

You really only have three options to reduce Mg. The first is to do nothing, stop dosing, and let the Mg fall on its own. The second is to do a water changes. One large one (65% or more) would work, as would 3 - 4 smaller ones (30% or more) over the span of a few days. The third is to buy a bucket of salt mix with lower magnesium, such as Red Sea's blue bucket, and do a few changes with that. Because the Red Sea salt has lower Mg than your salt mix, you would need fewer water changes to get the same drop in Mg.

Personally I would let the Mg fall on its own.

 

[whotzler]

Thanks for all the suggestions. I think I will do a 30% change with my current salt mix, to scared to try something new. 30% 1400 mag and 70% 1680 mag should get me around 1590. From there I will just let the tank consume it. Does any one know how to estimate mag consumption by DKH or Calcium consumption. Example, my tank consumes 2 DKH and around 13 calcium per day. Is there a formula to calculate Mag consumption based off that?

 

[chipmunkofdoom2]

Yes. For every 1 dKh of alkalinity consumed per day, Mg will drop on average by about 0.43 ppm. So your tank will consume about 0.86 ppm of Mg per day.

It's worth noting that Mg consumption can vary. Tanks with a lot of coralline algae will consume more. Tanks with more abiotic precipitation and less calcification will likely consume less.

 

[whotzler]

Yes. For every 1 dKh of alkalinity consumed per day, Mg will drop on average by about 0.43 ppm. So your tank will consume about 0.86 ppm of Mg per day.

It's worth noting that Mg consumption can vary. Tanks with a lot of coralline algae will consume more. Tanks with more abiotic precipitation and less calcification will likely consume less.

Thanks, that will at least give me a good idea of what to expect. Soooo adding around 100ppm per month and you may end up with high mag, like 1680 lol.

 

[chipmunkofdoom2]

Thanks, that will at least give me a good idea of what to expect. Soooo adding around 100ppm per month and you may end up with high mag, like 1680 lol.

Unless your tank is using about 3.8 dKh of alkalinity per day, then yes, this is likely the case

If you do a 30% change now and get your Mg down to 1,600 ppm, after four more 25% changes your Mg will be down to about 1,460 ppm. And that does not account for consumption, which will likely be occurring to some degree. So after a few months of no dosing you should be back to normal