magnesium levels for SPS

LPS, SPS and all coral chat
Olive
Posts: 19
Joined: Wed Jun 07, 2023 9:12 pm

magnesium levels for SPS

Post by Olive »

I've been struggling to keep my SPS happy lately. My magnesium levels are sitting around 1200 ppm, but I've heard conflicting advice on the ideal range. What's everyone else running for their SPS tanks?
lurecaster
Posts: 3
Joined: Fri Nov 25, 2022 6:56 am

Re: magnesium levels for SPS

Post by lurecaster »

1200 is kinda low, dude. I keep mine at 1350, and my Acros are poppin'. You gotta bump it up slow though, like 50 ppm per day.
rubyking
Posts: 3
Joined: Fri Jan 19, 2024 10:34 pm

Re: magnesium levels for SPS

Post by rubyking »

I've had success with 1300–1350 ppm. Anything lower and my montis start looking pale. What's your calcium and alk at? They all play together.
quart
Posts: 6
Joined: Thu Oct 10, 2024 9:31 pm

Re: magnesium levels for SPS

Post by quart »

My tank's been thriving at 1280 ppm. Not too high, not too low. Just gotta find that sweet spot for your system.
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dakora
Posts: 38
Joined: Tue Aug 02, 2022 2:54 pm

Re: magnesium levels for SPS

Post by dakora »

rubyking wrote: Sun Jul 20, 2025 11:59 am I've had success with 1300–1350 ppm. Anything lower and my montis start looking pale. What's your calcium and alk at? They all play together.
Yep, alk's gotta be stable too. If that's swinging, mag won't matter much.
flarion
Posts: 6
Joined: Thu Oct 10, 2024 3:56 pm

Re: magnesium levels for SPS

Post by flarion »

I aim for 1300 ppm. My SPS seem to do best there. How often are you testing? Could be a consistency issue.
coralmist
Posts: 5
Joined: Thu Oct 10, 2024 5:25 pm

Re: magnesium levels for SPS

Post by coralmist »

I'm new to SPS, but my LFS said to keep mag at 1250. Is that too low?
seafarer
Posts: 4
Joined: Thu Oct 10, 2024 5:18 pm

Re: magnesium levels for SPS

Post by seafarer »

1250 might work, but it's on the lower end. If your corals are happy, roll with it. If not, creep it up.
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Lumina42
Posts: 13
Joined: Fri Sep 30, 2022 7:35 am

Re: magnesium levels for SPS

Post by Lumina42 »

I run mine at 1350 ppm, and my SPS are growing like weeds. But like others said, stability is key. No point in chasing numbers if everything else is out of whack.
novate
Posts: 11
Joined: Sat Dec 24, 2022 10:22 am

Re: magnesium levels for SPS

Post by novate »

1200 is sketchy for SPS, bro. Bump it to 1300 and see how they react. My tank went from meh to wow after adjusting mag.
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