High Magnesium, would it negatively affect SPS?

[shandoee]

Recently I just did a 15 gallon water change on my system which is a year old, 60 gallon display with roughly 20 gallons of water in the sump. Mixed reef but mostly SPS dominated.

I have noticed that my WD and Mille have retracted polyps. All others are doing fine. The ORA pearl berry still has some PE but not as spectacular as before.
I keep my alk around 7.5, cal 500, and mg 1550 and I am using IO purple bucket. After the water change, my parameters are: dkh 7.95, Cal 5.49, Mg 1672, NO3 0, PO4 1.3
Mg levels shot up by about 120 ppm post water change.


Would very high magnesium levels have any negative effects on SPS? Mind you, my NO3 have always been reading at 0 on both hanna and nyos test kits.

 

[shandoee]

I edited the original post. I looked at my numbers on my fusion app and they have been at or near the1500s, not 1300s. Doh

 

[Spare time]

I doubt it. I have never experienced nor heard of magnesium in that range causing issues.


0 nitrate and high phosphate is an issue

 

[shandoee]

I doubt it. I have never experienced nor heard of magnesium in that range causing issues.


0 nitrate and high phosphate is an issue

Yeah I’m thinking phosphate might be the issue. My nitrates have always tested 0. The WD has always shown great PE even with 0 nitrates. I may try dosing nitrates. I feed very heavily, so that is contributing to the high po4. I actually don’t like dosing anything except for dkh and ca. Thank you for responding!

 

[Spare time]

Yeah I’m thinking phosphate might be the issue. My nitrates have always tested 0. The WD has always shown great PE even with 0 nitrates. I may try dosing nitrates. I feed very heavily, so that is contributing to the high po4. I actually don’t like dosing anything except for dkh and ca. Thank you for responding!

Alternatively, you could dose amino acids. The only thing to watch for is cyano (in which you could cut down on the aminos). The coral is probably getting by via the amount of feeding you do (via fish ammonia or whatever)

 

[Randy Holmes-Farley Verified Community Expert]

I suspect the high magnesium is test error. IO is not that high, and for a water change to boost it as much as you report would put it incredibly high in the mix.

 

[shandoee]

I suspect the high magnesium is test error. IO is not that high, and for a water change to boost it as much as you report would put it incredibly high in the mix.

Thank you for the response, Randy. I thought it was very high, especially when it went up after a water change. Initially I thought it could’ve been a bad batch so I went and bought another bucket of salt. Water change day is tomorrow so we’ll see. I have a new batch of trident reagents coming in tomorrow. I’ll test this against the salifert test kit as well.