Elevated Mag and its affects on SPS Growth?

[LebaneseDlight]

To all my reef chemists out there,

 

I've been keeping my Magnesium elevated to reduce Bryopsis and GHA (does it even work on GHA?) for about a month and a half. Although all of my Bryposis and most of my GHA is gone, my elevated Mag is a bit more stubborn and is very slowly declining back to normal levels. My salt, Tropic Marin Pre Reef, is apparently pretty high is mag level, as the last two weekly 20% water changes have only made small, incremental changes. My Mg was up to 1850 and is now about 1700-1750 (getting a water change ready for today, which should hopefully get it down to 1600~).

 

During this month+ of elevated Mg, I have not noticed much SPS growth. In fact, all of the white signs of growth have colored up. Given the relationship of Mg to Calcium, my Ca has been high at 490-510 depending on the level of Mg. I have not dosed any Ca during this time, only Alk about twice a week (and it's staying between 8.5-10 without any large swings). If my system cannot utilize the Ca in the water, then can this be the reason SPS is not growing at visible rate? Although I cannot see growth, the SPS seem healthy, polyps extended etc.

 

Also, two other reasons for poor growth could be elevated phosphates and nitrates. Although my test at home showed an unreadable level of nitrates, I took a water sample a few weeks ago to the LFS who said my Nitrates were at 20ppm. I did some spring cleaning in my back chambers (I wasnt using a filter floss in the overflow box, so there was a bit of detritus collected there) and am staying on top of my water changes. Also, I added a modded Aquaclear70 fuge, a Phosban reactor, and upgraded my skimmer to a Tunze 9002. All these factors should help bring down Phosphates (and hopefully put an end to the GHA as well, and help with SPS coloration).

 

Thanks for your input.

 

Tank Specs:

 

34 gallon Solana

Sg 1.025

Temp 79

Ca 490

Alk 9.5

Mag 1750

[Amphiprion1]

To all my reef chemists out there,

 

I've been keeping my Magnesium elevated to reduce Bryopsis and GHA (does it even work on GHA?) for about a month and a half. Although all of my Bryposis and most of my GHA is gone, my elevated Mag is a bit more stubborn and is very slowly declining back to normal levels. My salt, Tropic Marin Pre Reef, is apparently pretty high is mag level, as the last two weekly 20% water changes have only made small, incremental changes. My Mg was up to 1850 and is now about 1700-1750 (getting a water change ready for today, which should hopefully get it down to 1600~).

 

During this month+ of elevated Mg, I have not noticed much SPS growth. In fact, all of the white signs of growth have colored up. Given the relationship of Mg to Calcium, my Ca has been high at 490-510 depending on the level of Mg. I have not dosed any Ca during this time, only Alk about twice a week (and it's staying between 8.5-10 without any large swings). If my system cannot utilize the Ca in the water, then can this be the reason SPS is not growing at visible rate? Although I cannot see growth, the SPS seem healthy, polyps extended etc.

 

Also, two other reasons for poor growth could be elevated phosphates and nitrates. Although my test at home showed an unreadable level of nitrates, I took a water sample a few weeks ago to the LFS who said my Nitrates were at 20ppm. I did some spring cleaning in my back chambers (I wasnt using a filter floss in the overflow box, so there was a bit of detritus collected there) and am staying on top of my water changes. Also, I added a modded Aquaclear70 fuge, a Phosban reactor, and upgraded my skimmer to a Tunze 9002. All these factors should help bring down Phosphates (and hopefully put an end to the GHA as well, and help with SPS coloration).

 

Thanks for your input.

 

Tank Specs:

 

34 gallon Solana

Sg 1.025

Temp 79

Ca 490

Alk 9.5

Mag 1750

 

There's not much info out there on it, as I asked this question to Eric Borneman and another biologist (local) and they couldn't really find an answer. Granted, I was considering using Mg as a treatment for nudibranchs, not Bryopsis as well as even higher levels, but for shorter periods of time. Anyway, the only thing that comes to mind with elevated Mg is the increased solubility of calcium carbonate. Sounds great on paper, but the corals have a hard time calcifying without being able to precipitate it.

[LebaneseDlight]

Well, my Mg is now under 1500 and I have noticed a big difference. I had accidentally fragged my Digi a month back, and the fragged area hadn't changed (i.e., it wasn't encrusted with polyps and the cut was flat) for a month. Since lowering my Mg, the fragged area has healed itself and I've had an 1/8" of growth in a week over the cut. Maybe it's just coincidental timing...

[blasterman]

It's funny, but the highest growth SPS tanks I've seen lately don't dose mag or suppliments. They just tend add truckloads of calclium in their reactors, and rely on water changes to handle the rest. YMMV....

 

I know high mag helps with nuisance algae problems, but I've never noticed it do much else.

 

Phosphate is bad news at any detectable level. Nitrate below 20ppm should be fine. Some of us obsess to get zero nitrate, but if the tank has a natural tendencey to stay at 10-15ppm, I don't think it's that big a deal.

[franklypre]

I keep my Mg high just to keep my calc up, I shoot for 1500. I don't think it ever gets any higher that maybe 1550 and I tend to notice my PH stays more constant than when I used lower levels. Just my experience. Are you using a calc reactor, doser, or just pouring it in?

[LebaneseDlight]

I keep my Mg high just to keep my calc up, I shoot for 1500. I don't think it ever gets any higher that maybe 1550 and I tend to notice my PH stays more constant than when I used lower levels. Just my experience. Are you using a calc reactor, doser, or just pouring it in?

 

I don't even dose Ca! My salt Tropic Marin Pro Reef is high in Ca and have been doing 20% w/c. But since lowering my Mg to 1400-1500, my Ca has dropped to 450 and in just two weeks, believe or not, I've seen a big growth spurt.

[franklypre]

Very interesting, makes you wonder where it all went and why, good input though.