Picking brain's on magnesium

[Dirtyshoez]

My tank is about 3 months old and is consuming magnesium fast. Wanted to hear people's thoughts, here's what I have read and heard so far...

1st was told it was my salt, but I don't care to chalk it up to that and act like it may not be me or my tank... I have been reading and I am still fighting my way through the ugly stage however all my other parameters are good and I do all my due diligence. The main thing I read and want more feedback on is coraline growth. I have read that while coraline is attempting or beginning to plant itself the rock (specifically dry rock) will consume much magnesium while trying to stabilize a foundation for it to grow. About 6 weeks ago I dumped arcreef coraline spores into my tank, I do regular water changes and husbandry. I do have an algae bloom right now but that's just a part of the process, with my parameters in check other than maintenence I'm just living in it. So can someone give me feedback on this or input on if there is something I am maybe missing? I do have coral but at the rate of consumption I don't believe it is coral growth as it seems to be depleting by 60-80 ppm per day.

 

[Randy Holmes-Farley]

I don’t believe your tank is consuming magnesium at all. I’d stop testing it. It cannot ever be consumed faster than 1/10th of the calcium consumption, and to drop magnesium by a barely detectable 20 ppm, you need to consume more than 28 dKH of alk.

I suggest not measuring it at all:

Just say NO to magnesium testing: RMM is born

OK, this thread has been many years in the making, and I'm posting it here since folks in the chem forum are probably already tired of all the threads relating to problematic magnesium testing. I'm going to propose a method, let's call it the Randy Magnesium Method, or RMM for short. All good...

www.reef2reef.com

 

[Dirtyshoez]

Hm... thats interesting. So you're saying i should just watch my calcium and alk. And go from there? I monitor my alk daily, I was monitoring it all because I wanted to see what was going on on a day by day. But that is when I noticed my magnesium taking a hit after about a day on a fresh water change. So I took a sample to a LFS that does the aquaspin and the numbers were significantly lower than my salifert. So tried another LFS and numbers were sky high so I went home and did 6 tests back to back and all ranged around 1260-1290 with my salifert which was what I thought was correct but still the day before it was 1370. My calcium and alk stay within a range of 7.9-8.2 depending on time of day and my calcium depletes at a pretty normal rate. I keep the numbers around 400-420 calcium and would like the alk a little higher but I mean i figure if my mag is depleting then my alk isn't gonna plant it's feet anywhere.

 

[Euphylliaphyle]

If it is causing you lost sleep, you can have ICP testing done, but it's costly. Home (and LFS) Mg tests are notoriously inaccurate and twitchy. ICP will give you a result you can trust if you must know. If Ca and Kh are good and corals look happy, I wouldn't worry about it.

 

[Dirtyshoez]

If it is causing you lost sleep, you can have ICP testing done, but it's costly. Home (and LFS) Mg tests are notoriously inaccurate and twitchy. ICP will give you a result you can trust if you must know. If Ca and Kh are good and corals look happy, I wouldn't worry about it.

Sounds good, I don't think it is anything that is killing me. The tank is operating so I guess I will just keep on pushing and keep a not so close eye for a bit. I have a nano that I literally just let ride and it's kicking butt lol. So it very well be one of those you know what you gotta do but aren't listening type of things.

 

[Randy Holmes-Farley]

Hm... thats interesting. So you're saying i should just watch my calcium and alk. And go from there? I monitor my alk daily, I was monitoring it all because I wanted to see what was going on on a day by day.

Yes.

The variety of results you got demonstrate the futility of magnesium testing short of icp.

 

[Dirtyshoez]

Yes.

The variety of results you got demonstrate the futility of magnesium testing short of icp.

Randy, can you shed some knowledge on me about the relation of coraline and magnesium consumption. Is that factual?

 

[Tikki]

Hm... thats interesting. So you're saying i should just watch my calcium and alk. And go from there? I monitor my alk daily, I was monitoring it all because I wanted to see what was going on on a day by day. But that is when I noticed my magnesium taking a hit after about a day on a fresh water change. So I took a sample to a LFS that does the aquaspin and the numbers were significantly lower than my salifert. So tried another LFS and numbers were sky high so I went home and did 6 tests back to back and all ranged around 1260-1290 with my salifert which was what I thought was correct but still the day before it was 1370. My calcium and alk stay within a range of 7.9-8.2 depending on time of day and my calcium depletes at a pretty normal rate. I keep the numbers around 400-420 calcium and would like the alk a little higher but I mean i figure if my mag is depleting then my alk isn't gonna plant it's feet anywhere.

What’s your salinity?

 

[Dirtyshoez]

What’s your salinity?

1.025

 

[Tikki]

What’s your salinity?

1.025

You could mix your water a little heavier and the other numbers would raise respectively.

 

[Randy Holmes-Farley]

Randy, can you shed some knowledge on me about the relation of coraline and magnesium consumption. Is that factual?

I tend to not make clams that are not factual. lol

Coralline deposits high magnesian calcite, not aragonite that corals do.

Elemental analysis of coralline algae skeletons show it to be 2.0-4.4% magnesium (remainder is mostly calcium and carbonate). Most coral skeletons are in the 0.1-2% magnesium range

This article has much more discussion of magnesium, including a bunch of data supporting the above numbers. :

Aquarium Chemistry: Magnesium In Reef Aquaria

This article details the nature of magnesium in seawater, how it is added, measured, and removed from marine aquaria, and how it impacts the maintenance of calcium and alkalinity.

reefs.com

 

[Dirtyshoez]

Yeah I typically have it 1.026 but a batch ran 1.026 and I guess tapered off so when it mixed it in with my tank it ran low. So this last one I ran 1.027 and this one will read 1.026 but taper off to 1.025 again. So I ordered a Milwaukee refractometer and am going to see if I need to recalibrate my hanna. But my other numbers seem to run fine so it's just trial and error there.

 

[Randy Holmes-Farley]

Yeah I typically have it 1.026 but a batch ran 1.026 and I guess tapered off so when it mixed it in with my tank it ran low. So this last one I ran 1.027 and this one will read 1.026 but taper off to 1.025 again. So I ordered a Milwaukee refractometer and am going to see if I need to recalibrate my hanna. But my other numbers seem to run fine so it's just trial and error there.

Just an FYI, natural seawater at a sg of 1.025 will have 1212 ppm of magnesium while natural seawater at a sg of 1.027 will have magnesium at 1309 ppm. So those changes can make a substantial difference in magnesium.

 

[The Ugly Phase]

@Dirtyshoez do you have a build thread or can you tell me what corals you have my tank is 3 months old but yet too add any corals

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[Dirtyshoez]

Just an FYI, natural seawater at a sg of 1.025 will have 1212 ppm of magnesium while natural seawater at a sg of 1.027 will have magnesium at 1309 ppm. So those changes can make a substantial difference in magnesium.

Very good info, thank you sir.

 

[Dirtyshoez]

@Dirtyshoez do you have a build thread or can you tell me what corals you have my tank is 3 months old but yet too add any corals

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You can see them in my build thread but they aren't listed. But nothing to crazy, I have i think 10 different zoa frags, 2 favias, 2 acans, a shroom, a monipora and 2 acropora. I know some people will say i shouldn't have acros yet and blablabla lol. But I like em, I got a good deal on em, and they are doing great. Lol

 

[The Ugly Phase]

You can see them in my building thread but they aren't listed. But nothing to crazy, I have i think 10 different zoa frags, 2 favias, 2 acans, a shroom, a monipora and 2 acropora. I know some people will say i shouldn't have acros yet and blablabla lol. But I like em, I got a good deal on em, and they are doing great. Lol

do you know what par your acros are in?

 

[Dirtyshoez]

I don't but I will soon.. I bought a parmeter but the sensor was not working so I am waiting on my new sensor currently. But I keep them at the top and close to the gyres but I keep my lights fairly medium/medium high for now just because without the meter I want to make sure im not cooking my overall tank