Strange Mg problem

[Travis]

I need some advice on how to lower my Mg level. First, let me explain how it got to where it is. During the 17 months of this tanks life, it has almost always ran at around 1250 Mg. A few months ago I decided to try Seachem salt and it tested in the low 1100's for Mg. This slowly brought my tank Mg level down into the low 1100's. In larger tanks it is very expensive to raise Mg levels with products from our retailers so I decided to try a more "economical" way. I got a bag of Dead Sea Ice melt on a group order from another club. I followed the directions posted by members that have used this as well as Dr. Randy Holmes-Farley. The directions were to mix 9 cups of the ice melt with 1 cup of Epson salts in 1 gallon of DI water and dose that.
1-20-06, Mg = 1120, 2 cups of supplement added
1-21-06, Mg = 1190, 2 cups of supplement added
1-22-06, Mg = 1250, 2 cups of supplement added
1-24-06, Mg = 1265, 2 cups of supplement added
1-25-06, Mg = 1310, 2 cups of supplement added
1-27-06, Mg = 1370, no more supplement added
1-28-06, Mg = 1560, 90 gallon water change performed (80% Seachem, 20% Oceanic)
1-29-06, Mg = 1560
2-2-06, Mg = 1560, 90 gallon water change performed (100% Oceanic)
2-3-06, Mg = 1560

All tests were performed with my Salifert test kit. I checked my Salifert Mg test kit against a friend's and they both read the same. I checked it against my Seachem test kit's reference solution and it tested 130 higher than the reference solution. Seachem claims that their reference solution is verified by the University of Georgia's chemistry lab.

Do I have a faulty test kit or did the DIY Mg supplement that I used really mess up my water chemistry? Any suggestions for bringing it down? I'm going to start running my CO2 to the Ca reactor on a timer to slowly bring down Ca and Alk. We will see if the Mg also falls. I have 100 gallons of water change water made up but it is all Oceanic, which already has elevated Mg levels. Should I invest in some salt that has low Mg levels and do a couple WC's to see if it helps bring it down? My main concern is that:
1)The Mg level continued to rise days after I stopped adding the supplement and then peaked at 1560.
2)I have now performed 2 90 gallon water changes. Both with water that was far lower than 1560 Mg and my tank is still testing at 1560.

 

[Randy Holmes-Farley]

It looks like the supplement left you at 1370 ppm, which is fine. It does not do anything more to raise magnesium after the initial additions are mixed in (a few minutes to perhaps an hour in some tanks with sumps and refugia).

I do not know if the kits are accurate, but did you measure the salt mixes? Oceanic has excessive magnesium. I don't know about Seachem.

The only way to drop magnesium is to do water changes with a normal or low magnesium mix (like IO).
I would not conclude it is a big deal, but I'd try to bring it down over time.

 

[Travis]

Thanks Randy, I did not test either batch of water change water. I do have another batch made up from the same Oceanic bucket and will see what the Mg level is.

So Mg will not fall by by putting my CO2 to my Ca reactor on a timer to slowly bring down Ca and Alk? My current Ca and Alk levels are a bit high and I'm starting a new method of tank keeping that requires the alk to be down around 6-8 dKH so that is why I'm slowly going to bring it down. This method also requires Mg to be below 1400 so that is why I need to also get it down.

Any ideas as to why I added the last dose of magnesium supplement on 1-25-06 and the next day the tank tested at 1370, and then the next day after that it was 1560? Does this supplement take longer than usualy to effect the Mg level in the tank?

 

[Randy Holmes-Farley]

So Mg will not fall by by putting my CO2 to my Ca reactor on a timer to slowly bring down Ca and Alk?

No, that won't drop magnesium.
Any ideas as to why I added the last dose of magnesium supplement on 1-25-06 and the next day the tank tested at 1370, and then the next day after that it was 1560?[?B]

It either wasn't mixed in before the 1370, or one or both of the values is testing error. The effect is instantaneous.

 

[Travis]

Well, I figured out why my water changes did not bring the level down... I tested the Oceanic I'm using and it is at 1610. I will have to drain this 100 gallon batch down the drain and will then get a bucket of IO and do a couple WC's with that to bring my tank level down.

Thanks for the help Randy.

 

[Randy Holmes-Farley]

You could blend it off with IO if cost is a concern and you have a way to store it.

 

[Travis]

That is actually what I decided to do. I have some extra tanks laying around so I filled a few of them with the Oceanic WC water I had made up. I will probably use this whole bucket of IO doing 100% IO water changes first. Hopefully, that will get my Mg where it should be. After that, I will mix half of the Oceanic I have in the holding tanks with half IO until all of that Oceanic gets used up. Thanks again for the help.

 

[Randy Holmes-Farley]

Sounds like a good plan.

You're welcome and good luck.

 

[izzy_real]

Oceanic Salt Mix

Oceanic Salt Mix

Dr. Ron,

Thanks for making yourself available to all of us here on Reef Central! I'm working on my first batch of your Calcium, Alkalinity solutions, and I had a question about the Mg part:

I use Oceanic Salt Mix, and it works very well with my tank, and I'm wondering if I should dose the magnesium side of your solution, or just depend on my weekly water changes with Oceanic Sea Salt to keep that particular ion in it's proper concentration?

I have a 75 gallon tank, stocked with LPS mostly, one or two softies, and three SPS corals, fish, LR, and a crocea. With this bio load, I do between 12 and 16 gallon water changes weekly, along with cleaning my skimmer every four days or so! (Sorry for all the info., I just didn't want you to think I was a bad daddy!)

Do you think that is sufficient?

izzy

 

[Randy Holmes-Farley]

I use Oceanic Salt Mix, and it works very well with my tank, and I'm wondering if I should dose the magnesium side of your solution, or just depend on my weekly water changes with Oceanic Sea Salt to keep that particular ion in it's proper concentration?

If you are using a mix that has excessive calcium and magnesium, like Oceanic, then you probably should make certain adjustments. In this case, I'd just not add any magnesium until it drops below 1300 ppm.

Dr. Ron,


Randy, not Ron.

 

[izzy_real]

Gosh!

Gosh!

I'm going to change my avatar to Napolean Dynamite, because I'm such an idiot!

I knew you were Randy, and not Ron, I'm an idiot, GOSH!

Where did I get that?

Send me an e-smack..

75 Gallon Reef Setup - $2500

1 year premium membership at reef central - $24

Looking like an idiot on the World Wide Web - PRICELESS!

Sorry, and moving on!

izzy

 

[Randy Holmes-Farley]

Send me an e-smack..

:lol:

OK

:fun2:

No problem, anyway.