Tell me about magnesium!

[Aquattro]

So years ago, nobody heard of Mg, probably couldn't buy it if you wanted. Corals grew like crazy, and had brilliant colors.
Skip to modern day, and everybody is dosing Mg. It's missing from salt, and we even have vendors specializing in it.
So, from my side, I've never needed it. People tell me I'm wrong, and it's not like the old days, blah blah.
So my new tank, using new salt, is growing corals really well, and they have great colors, and everything is doing fine. So maybe, just maybe, I need to look into this Mg thing a bit more. I just read that Dez added something like 47 tonnes a year to get the tank he has, and I'd like mine to look like that in a year.
Skip to today, I went and picked up a Mg kit, and I measure 1350mg with a salifert kit.

So if you've read all this and are still paying attention, why do I have proper levels? It's been 2 weeks since water change, tons of new growth, just like the old days. Am I alone in my need to NOT dose Mg? The only thing I can think of is my Ca reactor. It's big, and melts a lot of rubble. Perhaps this is keeping my Mg at the right level? Do others with large reactors not need to dose either? I thought it was something every successful reef needed in the hobby today.

So tell me where you fit in the Mg scheme, and if you don't dose, why and what results do you get?

[The Grizz]

Well Brad first thing I would ask is what brand of salt are you using? Do you use any other additives? 1350 is good Mg levels, not sure what Dez keeps his level at but I have been told that 1400 - 1450 is optimal. I have not been able to test mine lately as my Elos test kit ran out of part c but I do know that I started to add Mg flakes from sivermax again and once I get a new kit I will test and bring mine up to level again. I think that SPS require more Mg, Ca and trace element to grow in our tanks as opposed to the ocean but I am in no way an expert on SPS that is for sure.

[Aquattro]

I'm using Reefer's Best, but my last tank, running IO, had similar levels.

[The Grizz]

I am not exactly sure how it works completely but I do know that keeping Mg levels up will hold Ca levels and maybe visa versa. I don't have a Ca reactor so I can't speak on that. It could be that Reefers Best has a high level of Mg and you coral is not demanding as much.

[StirCrazy]

I think Mg was depleted by DSBs. I needed to add it from day 1 when I had my DSB. when I got rid of my sand I only needed it to bring my water changes up to normal levels, which didn't take much with my IO. I was testing between 11 and 1200 in the IO so I would bring it up to 1350.

now I also found that when I hooked up my ca reactor with ARM media I didn't need as much also.

what I also found is that some people could use it with out even knowing. if you are pounding a Ca reactor to your tank and adding kalk through make up you could be masking the Mg condition. I could maintain my Ca that way with my old tank but I found that when I brought up the Mg I had to dial back my Ca reactor or my Ca would get to high.

I blame it on DSBs

Steve

[Aquattro]

Originally Posted by StirCrazy

I blame it on DSBs

Steve

Well, ya, but today's LED systems should counter that, no?? -lol

[don.ald]

Originally Posted by Aquattro

I'm using Reefer's Best, but my last tank, running IO, had similar levels.

off hand do you know the Mg reading in RBS salt?

[Delphinus]

I think our understanding has progressed in those years Brad. I started looking at Mg a long time ago, 5 or 6 years easily so it feels a little old hat to me now but it was an eye opener when I did start looking into things.

Now .. I can't honestly say I've noticed a difference with corals and Mg levels. The things I have noticed about Mg however:

1) Easier to maintain balanced Ca/Alk levels when Mg is right. When Mg is too low, it feels like I'm adding way more calcium to get it to raise. Also, a lot less precipitates out on powerhead impellers and so on. My salt mixing rubbermaid always had a 2mm thick layer of calcium encrustation over the whole surface and that stopped once I started mixing Mg into my makeup water before adding salt.

2) A.R.M. reactor media outputs a reasonable level of Mg so if you're using A.R.M. I would suggest that's why your Mg level in the tank is a solid "not bad" without even trying. You can also add Mg crystals from KZ to your media if you wish it to output a higher Mg but I always did find that Mg in my tank was never bad when I ran a reactor, it was things like my makeup salt had it too low and water changes were throwing the levels off.

3) I do notice when my Mg is low in the tank because the anemones don't seem to open as much. No idea why they care about Mg (ie. the biology behind this) but they do. I've seen it enough times to have a slight empirical basis to the observation. So having Mg at proper levels really doesn't hurt.

and

4) Although 47 tonnes in a year might be a slight exagerration nevertheless it is absolutely shocking how much Mg media it takes to raise Mg in a tank. A lot. I found with liquid additives I'd have to use up an entire $30 bottle to raise 24g of water change water to bring it from say 1100 (or whatever the starting point, depends on the salt I'd be using) to 1400 which is where I like my water change water to be. $30 per w/c is not sustainable so I switched to bulk and man I am going to miss LittleSilverMax/ChemMaster VERY much in this regard because buying from him was several orders of magnitude cheaper than bulkreefsupply.com. I just ordered some from BRS and the shipping was killer: I won't be buying bulk chems from them again. Off to Univar for me from now on.

5) I find that Mg depletion does occur in a system that also uses up Ca and Alk but it's a fraction of the depletion rates of Ca and Alk. So it's not really necessary to dose the tank unless you really want to - it's easy enough to maintain proper levels using water changes and tracking the Mg going in via w/c.

[dunl]

Gentlemen, please check out this thread:

http://www.canreef.com/vbulletin/showthread.php?t=72209

It's not pure calcium hydroxide....the other main element/ ingredient is magnesium.

Two birds, one stone.

[The Grizz]

Originally Posted by dunl

Gentlemen, please check out this thread:

http://www.canreef.com/vbulletin/showthread.php?t=72209

It's not pure calcium hydroxide....the other main element/ ingredient is magnesium.

Two birds, one stone.

This is interesting, I will have to check it out before I run out of Mag flake.