How to lower Magnesium without water changes?

[Anchor]

I recently did water changes, about 10% on 2 tanks. the next day I noticed all of my LPS corals were receding. I did not connect the problem right away so did another 10 percent on both tanks. IT GOT WORSE!!.. Aside from my 4 Euphylia and a Leptosiris coral I have lost most of my LPS. It was at this time I decided to test my newly mixed salt. Mg 1500 +, Ca 480 and Alk 7.2 to 7.6 at 1.025 salinity. Is there a way to lower Mg without buy new salt and doing water changes???

The box of salt was for 200 gallons and 3 of the 4 bags tested like this.. the one bag I have left I will use for my other tank as I cant go out and afford new salt at the moment.

Ideas would be appreciated if anyone knows a way. I can add that the parameters before water changes were within normal ideal before the water changes. As another note, it was a box of IO RC salt.. I know ya get what ya pay for sometimes.. just did not have theis kind of problem before.

 

[Brett S]

Magnesium is something that is rarely a problem. Quickly changing magnesium levels doesn’t usually affect corals and even high levels of magnesium are OK. And frankly just doing 10% water changes, even if the magnesium in the new water was sky high would be unlikely to create too much of a swing.

I suspect that something else is causing your problems.

But to answer your question, other than just waiting for the level to naturally decline (which it will eventually) a water change is the only other option. But I really don’t think it’s necessary here.

 

[SPR1968]

As far as I know, and as said above, the only way to reduce the magnesium level is with water changes.

I’ve been over 1500 with Magnesium with no issues whatsoever, and am actually tending to favour higher levels to be honest because of the interaction with the other elements and coral health, just from what I’ve seen in my own system.

I would suspect the problem may be something else, and as a basic, it may be worth trying a different salt brand.

Might also be worth checking nutrient levels in particular phosphate to make sure it’s not high, but I’m sure you have it under control.

 

[Halal Hotdog]

Apparently black mangroves use magnesium to help filter salt out. Not sure how much they use or how quickly, but some people reported a large decrease. Might be worth looking into if you plan to continue to use this brand of salt and want a lower magnesium level.

In your parameters you stated magnesium was 1500+. Did you stop titrating once you reached 1500 with no color change or continued past 1500? Salifert stops their scale at 1500 but you can extrapolate higher numbers based on a simple equation.

 

[bdare]

Which salt are you using?

 

[120reefkeeper]

As others have stated there are only a few ways to lower Magnesium. It would have to be very very high to be an issue.

Water changes with a salt that has a lower magnesium concentration.

Time.... let it drop naturally.

Add Montipora , they love magnesium for some reason . [emoji23]

 

[Anchor]

Apparently black mangroves use magnesium to help filter salt out. Not sure how much they use or how quickly, but some people reported a large decrease. Might be worth looking into if you plan to continue to use this brand of salt and want a lower magnesium level.

In your parameters you stated magnesium was 1500+. Did you stop titrating once you reached 1500 with no color change or continued past 1500? Salifert stops their scale at 1500 but you can extrapolate higher numbers based on a simple equation.

I was not adding any Mag to the system, figuring water changes would be enough. My concern is that it is suddenly 1500 (using Salifert) without any additions on my part. Ca levels were very high as well. And I only added small amounts of Ca on a weekly basis depending on testing levels. Water changes were every 3 to 4 weeks.. Thus my confusion.. a sudden increase in Mag, huge actually, and Ca stressed out the corals. I emptied the syringe on the test.. did not continue.. Mg was running about 1350 to 1380 on weekly testing. Ca about 400... Alk was 8.5 ish.. then dropped without any new additions.. IO fresh mixed showed very elevated levels of MG, CA and low levels of ALk.. below 6.. and of course I cant find the receipt.. So I am still calling it the salt.. Phos and Nitrates all reasonably low.. .05 and 10ish for Nitrates. tested parameters were essentially backwards from what would be expected from IO reef salt.

 

[120reefkeeper]

I was not adding any Mag to the system, figuring water changes would be enough. My concern is that it is suddenly 1500 (using Salifert) without any additions on my part. Ca levels were very high as well. And I only added small amounts of Ca on a weekly basis depending on testing levels. Water changes were every 3 to 4 weeks.. Thus my confusion.. a sudden increase in Mag, huge actually, and Ca stressed out the corals. I emptied the syringe on the test.. did not continue.. Mg was running about 1350 to 1380 on weekly testing. Ca about 400... Alk was 8.5 ish.. then dropped without any new additions.. IO fresh mixed showed very elevated levels of MG, CA and low levels of ALk.. below 6.. and of course I cant find the receipt.. So I am still calling it the salt.. Phos and Nitrates all reasonably low.. .05 and 10ish for Nitrates. tested parameters were essentially backwards from what would be expected from IO reef salt.

IMHO the magnesium being at 1500 wouldn’t be the cause for worry . The sudden Alkalinity drop is more of an issue . You’ll need to slowly raise that up over time ... try not to increase more than 1dkh per day if you want to stay safe.

Just a quick question... did you mix the salt in the bag or bucket before using it? Sometimes people have noticed the same issue you’re talking about and they didn’t mix up their salt before use. The theory behind this is that different additives within the mix can become stratified inside the packaging during shipment. So you could end up using scoops that are made up of more magnesium and less Alkalinity as an example.

 

[OutsideBrian]

Have you calibrated your refractometer recently? If it was off and you were actually saltier that might account for some of the higher numbers.

 

[Jet915]

Yeah, i usually try to keep my mag around 1500 so I dont think thats the problem.

 

[johnalicia]

something else other then mag is my vote as well. I keep mine at 1450.

 

[Reefs and Geeks]

I recently raised my mag from 1350 to 1600 over 3 days with no issues at all. I agree that magnesium is an unlikely cause of your issues. You can safely dose up to 100ppm of magnesium at once without issue, so your new salt mix would have to have astronomical mag to raise your levels significantly by a normal sized water change.

I have, however, had issues when doing a water change that had much higher alk than my tank. What alk do you run your tank at and how does it compare to your newly mixed salt? I'd suspect it to be the easiest thing to cause an issue in normal circumstances.