Persistent high magnesium ...

[Cenglezopoulos]

Good morning/good evening everyone,

So I ve got this 60 liter reef tank which has been running since 09/2016. Around 12.2016, alkalinity and magnesium reached values around and above upper limits ( KH 11+, Mg >1500) and refused to decline despite water changes. It was like corals stopped consuming everything. I used no chemicals to reduce them, just turned off the dosing pump. After one month with the KH channel off, KH values gradually dropped to 7.7 so the day before yesterday I started adding again. So I ve been adding Seachem Carbonate for 2 days now ... Magnesium channel is also turned off since Xmass but magnesium is still in high levels (1500 and over). I don' t know what to do. Anybody has any ideas ? Thank you very much.

Costas,
Greece.

 

[CodyRVA]

I personally wouldn't worry too much about high MG, many folks have maintained high MG to combat things like bryopsis, although thats an entirely different debate. Ultimately it shouldn't hurt anything; I know a reefer who maintained 1600 MG all the time. If you do want to bring it down, what salt are you using? You might be adding as much MG by water changes as you're taking out. Do you have a lot of coral? Keep in mind MG levels are generally easy to maintain as very little is typically utilized. My 80G system needs 5-10 ml a day max, so it may take longer than a month to drop, especially if your salt mix is adding MG back in. What size are your water changes?

 

[Randy Holmes-Farley Verified Community Expert]

Magnesium depletion will be unnoticeable in that tank and will stay wherever it is in the salt mix you are using.
Real depletion will be roughly 2 ppm or less for each 2.8 dKH of alkalinity depleted.

What salt mix are you using?

 

[Cenglezopoulos]

Ι am using Aquaforest .... but its not the salt ... I measured the water before water change and Mg was 1365 ... so its not the salt ...
I dont mind staying that high if it can cause no harm .....

 

[Cenglezopoulos]

I have some corals which are not big...I dont think they consume much.... 9 zoanthids, 5 ricordee, a clam, one bubble tip anemone, and a few sps frags (3 montiporas and 4 acroporas)

 

[bfsaunde]

I had the same issue until I realized my RedSea Pro test for Mg was reading about 300 ppm high. I bought a Nyos kit and turns out my Mg was fine. Have you had someone else test the water. What Mg test kit are you using?

 

[Randy Holmes-Farley Verified Community Expert]

Ι am using Aquaforest .... but its not the salt ... I measured the water before water change and Mg was 1365 ... so its not the salt ...
I dont mind staying that high if it can cause no harm .....

Elevated magnesium is either from the salt, overdosing a supplement, or testing error.

 

[Cenglezopoulos]

Well perhaps I overdosed initially ... even if I was measuring every day. But pump is closed since X mas ...

 

[Cenglezopoulos]

I had the same issue until I realized my RedSea Pro test for Mg was reading about 300 ppm high. I bought a Nyos kit and turns out my Mg was fine. Have you had someone else test the water. What Mg test kit are you using?

Yes I ve double checked with a fellow reefer .... I am using salifer

 

[bfsaunde]

I understand you are looking to see if this could potentially harm things in your aquarium. For someone to answer this, because I am not sure I can, you will need to provide the actual amount of Mg in your system. You stated above that it is >1500. I don't own any Salifert test kits, but I am assuming you can just keep adding reagent by refilling your reagent syringe and just keep calculating so much reagent equals so much more ppm of Mg until the sample turns to the proper color. Someone here with a Salifert test kit, may be able to assist.

 

[Randy Holmes-Farley Verified Community Expert]

Yes, add a second syringe of fluid to the endpoint.

 

[GoVols]

I had the same issue until I realized my RedSea Pro test for Mg was reading about 300 ppm high. I bought a Nyos kit and turns out my Mg was fine. Have you had someone else test the water. What Mg test kit are you using?

+1
I switched to Salifert and it's a lot quicker than the Red Sea Pro kit too

 

[Cenglezopoulos]

I understand you are looking to see if this could potentially harm things in your aquarium. For someone to answer this, because I am not sure I can, you will need to provide the actual amount of Mg in your system. You stated above that it is >1500. I don't own any Salifert test kits, but I am assuming you can just keep adding reagent by refilling your reagent syringe and just keep calculating so much reagent equals so much more ppm of Mg until the sample turns to the proper color. Someone here with a Salifert test kit, may be able to assist.

Of course... I ve already done that. It has been between 1480-1560 .... this is the range of values I ve been constantly getting ...

 

[GoVols]

I dont mind staying that high if it can cause no harm .....

I don't know of any long term harm but RH-F may correct me on that

I'm here to learn too

In the past, I've had my mag up to 2100 and hold for about six weeks to knock out Bryopsis.

 

[bfsaunde]

Ok- I'm pretty sure that range will be fine. I will let others weigh in. Water changes will bring it down over time.

 

[Cenglezopoulos]

Thnks a lot guys ..!!