low magnesium

[sooju]

First, since I know you'll ask, my parameters:

temp 78, SG 1.025, pH 8.0, ammon/nitrites 0, nitrate 10
alk 10, CA 400, Mg 990

I'm using SeaChem Reef Salt and have been doing 8-10% PWCs weekly. I'm having trouble getting my magnesium up. I bought the B-Ionic two part buffer but haven't really used it since my CA/alk seem okay, and I also bought the B-Ionic magnesium buffer but I'm not sure how much to add.

My total tank capacity is 70G and I feel like an idiot but I can't understand the label for the mag supplement. It says to add 1.5 ml per gallon of capacity each day to raise the level by 15 ppm. That would mean 105 ml a day. The bottle is only 946 ml so is this bottle only enough for nine days or 135 ppm? My current level is 990 and I need to get over 1300.

Am I missing something here or is this whole 32 oz bottle not enough to get me where I need to be?? There's got to be a typo or I'm reading something wrong. Please help!!

 

[Ziggy953]

This is what I found about B-Ionic MAG supplement

The way I read it is, 1.5ml will raise 1 gallon of water by 15ppm. I don't think you want to put 105ml in your tank. I believe you need to only add enough to raise your mag levels by about 210 to get to 1300ppm. Make more sense?

[FONT=Arial, Helvetica, sans-serif]B-Ionic Magnesium[/FONT][FONT=Arial, Helvetica, sans-serif]

Through the chemical process known as "ion-pairing",
magnesium ion concentration influences the saturation
point for calcium carbonate in solution. In general, the
further the magnesium concentration drops from natural
seawater levels (1350 ppm), the more difficult it becomes
to maintain adequate levels of both calcium and alkalinity.
Magnesium also plays an important role in stabilizing pH by
interacting with the buffer system of seawater.[/FONT] [FONT=Arial, Helvetica, sans-serif]B-Ionic Magnesium is an easy to use one component liquid
supplement which, when used with B-Ionic Calcium Buffer
or kalkwasser, will not disrupt the ionic balance of closed
marine aquaria. B-Ionic Magnesium contains 60,000 ppm
magnesium, and one mL will raise one gallon of
aquarium water by 15 ppm.[/FONT]
​

 

[Kurt_Nelson]

It says to add 1.5 ml per gallon of capacity each day to raise the level by 15 ppm. That would mean 105 ml a day.

You're correct... 1.5 ml/gallon x 70 gallons = 105 ml to raise your tank's magnesium level by 15 ppm. But from the info that Ziggy pasted, looks like that blurb says 1.0 ml/gallon raises you 15ppm. Seems to be a discrepancy there somewhere.

Have you tested your new salt water before putting it in the tank? I'm finding it hard to believe that your magnesium is that far off, with your Ca and alkalinity being where they are. I'm wondering if it isn't just an error in testing.

If your new salt water is coming in that low, that's a problem that might make you think again about salts. But if your new salt water is testing normal for magnesium, then it just sounds like you have to just dose your tank up to "normal" and you'll probably stay balanced from there on, and you won't have to continually dose for magnesium.

 

[sooju]

Have you tested your new salt water before putting it in the tank? I'm finding it hard to believe that your magnesium is that far off, with your Ca and alkalinity being where they are. I'm wondering if it isn't just an error in testing.

Great suggestion, thank you. I just tested my water for PWCs and it was 1080.

If the problem is my salt then I'm in trouble - my LFS had a sale over the weekend and I picked up another bucket. I have enough to make about 225G. That's like six months of PWCs.

Could it be a bad test? It's a Salifert test with a 2011 expiration date.

Of course, it could always be user error but I've read the instructions really carefully and I can't find anything I'm doing wrong.

I'm not sure why there's a discrepancy between the bottle label (1.5 ml/gallon) and the website (1 ml/gallon). Either way I find it hard to believe that this whole 32 oz bottle can only raise my mag reading by 135 ppm. At that rate it will take me 24 days and almost 3 bottles to get to the right level. Something is just not adding up here.

 

[ccCapt]

Use the Reef Chemistry calculator, fill in the blanks, choose B-Ionic from the drop down and you will get your answer.
According to the calculator, for 70g at 900 ppm, you need to add 94.6 fl oz or 560 tsp of B-Ionic liquid to get to 1300. You shouldn't raise mag more than 100 ppm per day.

 

[Ziggy953]

Just to make sure you are clear...you should not raise the Mag more then 100ppm in a 24 hour period. Make sure that you are testing you mag levels 24hours after you dose.

 

[Kurt_Nelson]

Great suggestion, thank you. I just tested my water for PWCs and it was 1080.

Hmm... that's going to be an issue if you're doing corals. Can't remember if you are going that route.

Salifert is pretty darn good, and you're right... it's tough to mess that one up on a user error standpoint. I use it so I'm familiar with it.

Do you know anyone else that can confirm/deny that reading with another test kit? Or your LFS? I'm not familiar with that salt, so I'm not sure if that's a normal reading for it or not. I kind of think not.

{Edit: I just remembered I had a copy of the AWT "Salt Test Report" stashed on my computer and looked up the Seachem Reef Salt. In the two samples they did, they came in at 1260 and 1510 for magnesium. Something doesn't seem right with your salt and I'd make sure of your reading before dosing anything!]

 

[sooju]

I just looked up on Seachem's website and their guaranteed analysis for magnesium for "Reef Salt" is 1318. So the test must be wrong, right??

The next time I go to my LFS I will bring a water sample with me. I've never done that before - do you just give them a couple ounces and they run it through a machine? I can't imagine that they put it in a bunch of small vials and test each thing separately. Takes me about 20 minutes to do all my tests...

Thanks again, as always, for the great suggestions!

 

[sooju]

Use the Reef Chemistry calculator, fill in the blanks, choose B-Ionic from the drop down and you will get your answer.
According to the calculator, for 70g at 900 ppm, you need to add 94.6 fl oz or 560 tsp of B-Ionic liquid to get to 1300. You shouldn't raise mag more than 100 ppm per day.

Great link, thanks! The bottle says not to raise it by more than 15 ml a day, but it sounds like I could go a little faster than that? Once I figure out if the level really is that low? I won't go up by more than 100 ppm a day.

 

[jonboyb]

I use SeaChem Reef Salt and mix it almost identical to you, up to an SG=1.025. However, when I get to 1.025 salinity, my pH is usually 8.3-8.4. You are showing 8.0. Mag usually comes in over 1350 and calcium tends to be around 420. Maybe just a bad batch of salt. I love the SeaChem. I have several corals now and with bi-weekly PWC's of about 25%, I still haven't had to dose anything....although my calcium levels usually dip to around 390-400 by the end of a 2 week cycle so I'll likely start dosing that now.

 

[sooju]

Ooh, another idea! I can mix up a gallon of RO with the new salt bucket to see if I get the same mag reading. will keep you posted...thx

 

[jonboyb]

I don't know about you, but it usually takes considerably more than the 1 cup salt/2 gallons water to get me to my SG=1.025. Are you using RO/DI?

 

[sooju]

I mix up enough for a few weeks at a time. I have a big garbage bin that I fill with RO (roughly 17 gallons) and I add salt by weight - it ends up being around 4 3/4 lbs. I think the amount suggested on the label is for 1.023 so I added a little when I was figuring out how much my full bin would take, but it was pretty close to what was suggested on the label. Sometimes I have to adjust it a little up or down.

As far as I remember there was a volume measurement on the label too - so hopefully I can mix a small quantity for the purposes of ruling out a bad batch the first time around...

If the magnesium is indeed too low I'm hoping it doesn't do any permanent damage. I only have two zoas and one torch at the moment but I don't seem to be able to go to the LFS without picking up another one. Good thing they're 1/2 hour away!!

 

[sooju]

Maybe just a bad batch of salt.

Mystery solved, I think. I made up a gallon of RO/DI water and mixed it up to 1.025 SG from the NEW bucket of salt and the magnesium came in at 1310. So the original bucket must have been bad.

So I guess I need to start dosing heavily (no more than 100ppm per day) to get the tank from 1,000 to 1,300 and then start using the new salt bucket. I wonder if I call Seachem if they'll replace the defective one.

 

[Kurt_Nelson]

Glad to hear you got it figured out. Too bad though that your tank ended up so low. I don't have any experience with low magnesium, but I would think that for the short length of time it's been low, you shouldn't have any problem.

In the process of raising it, I'd personally go the slow route and only raise it 10-15 ppm per day. And I'm pretty sure Seachem, or your LFS, will refund you for that bucket of salt. Either that, or they'll give you the "hmm... y'know you're supposed to remix all that salt up in the bucket before use because it settles into layers during shipment" speech. And no... I never do that.

Ever since Reef Crystals recently had that supposedly weird batch with low Ca, I've always done a complete series of tests of a sample of water made from the first scoops from a new bucket. It's just good piece of mind, and an easy way to catch something quick if I happen to get a "bad" bucket.

 

[sooju]

I've always done a complete series of tests of a sample of water made from the first scoops from a new bucket. It's just good piece of mind, and an easy way to catch something quick if I happen to get a "bad" bucket.

Well I know that -- now. How come I need to learn everything the hard way?

 

[Kurt_Nelson]

Because we all did too!

But honestly... that "testing the new bucket" thing is relatively new for me. Makes sense after you think about it, but you just assume the salt is made correctly, right? Go figure.

 

[sooju]

So I called Seachem this morning and they gave me this whole story about how much they test all their products before they go out the door. The basic message was that it was impossible for my salt to be bad. They want me to send a 2 cup sample to their tech support team for analysis and then "they will be in touch." We'll see.

 

[Ziggy953]

Ever since Reef Crystals recently had that supposedly weird batch with low Ca, I've always done a complete series of tests of a sample of water made from the first scoops from a new bucket. It's just good piece of mind, and an easy way to catch something quick if I happen to get a "bad" bucket.

Just out of curiosity, how much water do you mix at a time when you do PWCs?

 

[Kurt_Nelson]

Just out of curiosity, how much water do you mix at a time when you do PWCs?

I only change out 4-5 gallons a week. (46g tank). I try to keep between 15-20 gallons of saltwater stored and usually mix up a couple buckets of 3.5 gallons each when the storage tub gets low.