BRS 2 part Magnesium, how much do I dose?

[Sleepydoc]

+1 on the issues with the Red Sea Mg test. I used it for a couple years without issue, and then had some random low issues. I'm pretty sure there's something in the test that is prone to interference/error as many people have had issues. I like the other Red Sea tests, though.
The nice thing about Mg is that you have a wide range of 'acceptable' Mg values, so if you're off a bit with your dosing it's not the end of the world.

 

[FugeTown]

+1 on the issues with the Red Sea Mg test. I used it for a couple years without issue, and then had some random low issues. I'm pretty sure there's something in the test that is prone to interference/error as many people have had issues. I like the other Red Sea tests, though.
The nice thing about Mg is that you have a wide range of 'acceptable' Mg values, so if you're off a bit with your dosing it's not the end of the world.

I don't have the Red Sea test kit. I actually tested my magnesium once got a reading of 1320 and bulk reef supply's calculator said to add 3 oz of 2 part magnesium to raise level to 1360 and sure enough after I added 3 oz the Magnesium tested exactly 1360. I'm confident that my salifert Magnesium test kit is spot on , I love it.

 

[FugeTown]

I'm glad you like it.

In general, I'd dose it based on the recommended recipe and not the magnesium level (unless it is already too high) because it adds more than just magnesium (the sulfate is important too), and dosing as recommended will keep the magnesium more stable than waiting until it gets out of whack and dosing a bunch.

Hey there Randy just thought I'd chime back in on this thread. My Magnesium finally stabled out it drops about 10 to 20 ppm a week now which is nice and I've been studying your reads about proper balanced levels of calcium to alkalinity. I've also been reading your article about how some corals in a higher nutrient system grow faster with a slightly higher alkalinity level so I decided to give all of this a whirl using the reef calculator of course. First of all my alkalinity was at 9.5 so I decided to raise it to 10.5 and then I checked my calcium level which was 400 so I added the Fluval liquid calcium slowly to raise my level to 435 as recommended on the reef calculator. I'm going to try to keep these numbers balanced now that I'm starting to understand what's going on to see if it makes a difference with my lps dominant tank. My Magnesium was at 1410 and ph was around 8.0-8.1 . I wanted your opinion on how you think I'm doing so far with my numbers ? One other question is how important is keeping an eye on my phosphate level because I have an API test kit but doesn't seem to give readings on low amounts of phosphates and always reads zero. So I was thinking of maybe picking up a salifert phosphate test kit unless you have a recommendation other than the Hanna checker. Thanks for all your knowledge it's nice to learn this stuff and get better and better at reefing .
Oh yea noticed your in Massachusetts, I'm located on Cape Cod

 

[Newb73]

Anecdotal.

I believe large colonies of zoas are mg sinks. They produce a deadly neurotoxin and its no secret we give IV magnesium sulfate for things like preventing premature labor by stopping uterine contractions and malignant hypertension by relaxing systemic vascular resistance.

My tank definitely uses a higher ratio of mg to CA/Alk than it should.

It is however difficult to quantify exactly as i am very pro water change and am alternating between fritz and I&O.

 

[FugeTown]

Very nice, I wish I had more time to do more water changes and stuff to mine but I'm a very busy person so I'm always modifying my system to compliment that. I do a water change once a month though which is pretty good for me and in between I dose Dr Tims. I'm eventually going to build a chaeto reactor so I can feed the hell out of my tank and not worry about that nutrient sweet spot. I had chaeto before when I still had my fuge and it worked like a charm but my tank isn't drilled so I constantly had to finagle the overflow which was a royal pain so that's why the reactor is gonna be nice for my situation. About the zoas ever since I started feeding them roids it's been night and day , my zoa colonies have filled in nice and growing fast , love that stuff but gotta go easy on how much I use.

 

[Randy Holmes-Farley Verified Community Expert]

Anecdotal.

I believe large colonies of zoas are mg sinks. They produce a deadly neurotoxin and its no secret we give IV magnesium sulfate for things like preventing premature labor by stopping uterine contractions and malignant hypertension by relaxing systemic vascular resistance.

My tank definitely uses a higher ratio of mg to CA/Alk than it should.

It is however difficult to quantify exactly as i am very pro water change and am alternating between fritz and I&O.

I think the idea that soft corals use a lot of magnesium in any way is not supported by the scientific literature, and seems extraordinarily unlikely. Soluble inorganic ions are not generally stored in cells in high concentration, and if it is not way higher than seawater (which is already pretty high in magnesium), then such organisms cannot be a big sink.

 

[Newb73]

I think the idea that soft corals use a lot of magnesium in any way is not supported by the scientific literature, and seems extraordinarily unlikely. Soluble inorganic ions are not generally stored in cells in high concentration, and if it is not way higher than seawater (which is already pretty high in magnesium), then such organisms cannot be a big sink.

It's a mystery then. When using only IO and not dosing i have seen extremely low mg levels and at times had to dose quite a bit of the BRS version to get my levels above 1350. Quite a bit more than the formula calls for.

I suppose it's possible that what i saw as consumption was just the result of water changes where i was replenishing some calcium but had an extremely mg poor batch of IO.