Magnesium Level Maintenance

[Mattfish]

We're testing and dosing Magnesium in an effort to get it up to where it needs to be (1330-1500). We're running around 1140 or so right now.

We're adding 6 tbsp of SeaChem Advantage Reef Magnesium daily, but the level still won't rise. Our Ca is 460 or so and stable, and our Alk is 10-11 and stable. Our pH floats between 8.18 and 8.29 within any typical 24 hour period. All seems normal except for raising the Mg.

My assumptions are:
1. That SeaChem Mg does allow the level to reach 1500 or above, i.e. it doesn't have a limitation due to it's formulation
2. That the corals are using the Mg as fast as we add it due to need, and the fact that our Mg was very low (920-940) for a long time when we weren't testing it and we were having our tank serviced for us.

Boomer, if you're out there, any chemical reason behind this, and any good/better ways to solve this? Is there a better Mg additive to use?

 

[Woodstock]

Faulty test kit? Which test kit are you using?

Are you using the calculator to know how much mg to add?
Reef Chemistry Calculator

 

[Mattfish]

Good question - it's a Salifert, and the results are consistent, which doesn't mean it's not compromised, and I have a new Salifert kit coming tomorrow to check it with....

I read the thread on test kits, and while we could all use a digitally calibrated means to be sure, the Salifert's may not be perfect, but they're better than average. Which doesn't mean I shouldn't consider a switch to Lamotte when these run out....

 

[Woodstock]

Salifert's mg test has always served me well.

6 tbls isn't much. How many gallons is your reef?

 

[Woodstock]

The calculator link I gave you above says to use 199.5 teaspoons of Seachem Reef Adv Mg to raise 100 gallons from 1140 to 1350 ppm.

As you can see, it takes a LOT of magnesium to raise the levels in our reefs. Also, keep an eye on salinity being that magnesium is a salt.

 

[Mattfish]

We've got a 130g with a 50g sump/fuge... How much would you recommend?

 

[Woodstock]

Guessing a total water volume of 150 gallons, it will take 299 teaspoons (52.75 oz) to increase it from 1140 to 1350ppm.

Do NOT dose all at once but instead dissolve the supplement in water and slowly dose over the course of several days.

 

[Mattfish]

Thanks for this - that's a LARGE amount and we'll have to step up our dosing slowly so we don't hurt the tank. Really appreciate it!!

 

[prow]

yup sounds about right, 30ish Tbls premixed with RO/DI water for the next 3days or so. after you get with in range dosing will slow big time.

FYI; test your salt mix and dose Ca+, Mg+ and alk and make adjustments before doing water changes. many salts are pretty low in Mg+, just a heads up to check on it.

 

[Mattfish]

Thanks both of you for the help with math on this - we'll start with 10 tbsps per day on this and see how we do - I don't want to overdo it but 1/3 of the amount needed seems like a reasonable amount per day - right?

 

[prow]

for Mg+ you want to make adjustments of 100 or less with in 24 hours. 30 tbls should raise your Mg+ about 60-70ppm. so yeah this dosing would be ok. 10 tbls will only raise Mg+ about 20ppm, which will take a couple weeks to get Mg+ to the levels you want, not including any Mg+ that may get used up.

 

[JoJo]

this is some good info, thanks

 

[Mattfish]

for Mg+ you want to make adjustments of 100 or less with in 24 hours. 30 tbls should raise your Mg+ about 60-70ppm. so yeah this dosing would be ok. 10 tbls will only raise Mg+ about 20ppm, which will take a couple weeks to get Mg+ to the levels you want, not including any Mg+ that may get used up.

Thanks - I did the math here and realized we were talking about 10 doeses of 2 tbsps each, so 20 tbsps total, or 60 tsps. We'll see if we can take it a bit higher than that..... but not over 100 ppm total movement per day.

 

[Frankie]

Any updates?

 

[Mattfish]

Thanks for bringing this back up. Yes - success. We used a lot of Reef Magnesium to get most of the way there, and since we started doing our own water changes, got the rest of the way there with them. Mg is now 150-1400 or better - haven't checked in 2-3 days - and Alk is staying nice and low at 8 to 9, Calcium staying high at 450 -470.... Corals are doing AWESOME!

 

[fatman]

Suggestion, in the future check the magnesium, calcium, and alkalinity level of your tank before doing every water changes and add the supplments needed to your water change water to bring your tank magnesium levels up, unless you have extreme heavy calcium needs this is usyually the easiest metod, other than a calc reactor or a ATO with Klakwasser. This is assuming your magnesium, calcium and carbonate levels of your newly mixed salt is at a level near that which you want to mainatin. What is your present number and types of corals?

 

[Woodstock]

Thanks for bringing this back up. Yes - success. We used a lot of Reef Magnesium to get most of the way there, and since we started doing our own water changes, got the rest of the way there with them. Mg is now 150-1400 or better - haven't checked in 2-3 days - and Alk is staying nice and low at 8 to 9, Calcium staying high at 450 -470.... Corals are doing AWESOME!

Glad to hear all is well


Fatman - good point. Testing the newly made saltwater and adjusting as needed prior to use is important!

 

[Mattfish]

It is a very good suggestion. In fact, we started testing the tank before the water change each week, the water we're going to put in, until it comes to where we want it, and then the tank after we put the new water in - about 4-8 hours later, depending on when we get it done. Also, with the AC3 Pro, we obviously get some immediate feedback, although I don't consider it valid until the water's had a chance to recirculate for a while.

As for coral, there's too much to list - it's a "well decorated" tank. Pictures would be easier, and I need to update our ReefSpace page in the next few days.

 

[BobBursek]

Kent Thec M has the highest concentration of Mg.