Unstable magnesium level

[Jon]

I am really struggling with maintaining my magnesium levels where they should be. I seem to be adding about 3 ounces of Kent Marine Tech M every other day and the levels continue to drop and not rise. I have no problem with maintaining my alkalinity from 10-12 and my calcium from 420 - 460. Every other day I dose 3 tsp of Kent Superbuffer DKH and 2 ounces of Kent Calcium and 3 oz of Kent Marine Tech M . The salt that I use is Instant Ocean and I do a 10 gallon water change every two weeks. I use a Red Sea test kit for the magnesium 24 hours after the water change and my magnesium is usually around 1200. Than after the water change every two days I test my alkalinity, calcium and magnesium and the calcium and alkalinity are always good except the magnesium. I only have a couple small pieces of coral in my tank and 5 fish. Can anyone explain why this is and if there is something I should try differently.

Thank - Jon

 

[pgordemer]

What is your actual MG from a test?

It can take a ton of MG to intially raise it (at time almost a gallon if below 900), but once its up there, then it can take as little as 20 oz a month to keep it there.

 

[Jon]

Yesterday it read 640 so I added 8 oz and today it read 840 so I added another 8 oz.

I had no idea it would take so much to bring the levels up to par. I will continue to monitor the levels daily and will dose heavy until they are there. Guess I will need to order another 64 oz jug from Marine Depot AGAIN. God my wife is going to shoot me one of these days.

Jon

 

[mott768]

I had the same problem when I used IO salt, it took daily dosing for about 2 weeks to get the level up and stay up but once I did a water change then I had to start dosing again. Someone told me they had the same problem with that salt and once they switched salts it went away. When I switched to RC salt it did, I now use TM pro.

 

[pgordemer]

Yesterday it read 640 so I added 8 oz and today it read 840 so I added another 8 oz.

I had no idea it would take so much to bring the levels up to par. I will continue to monitor the levels daily and will dose heavy until they are there. Guess I will need to order another 64 oz jug from Marine Depot AGAIN. God my wife is going to shoot me one of these days.

Jon

I would suspect your test kit, 640 is almost off the scale on the low side, even IO salt has more than that.

You can buy MG in bulk and get gallon packs alreay mixed (MG sulfate and MG cloride) from http://www.bulkreefsupply.com/Two-Part-Kits/c52/p493/Replacement-Magnesium-pack-(Full-Gallon)/product_info.html for only $9 a gallon.

If you are going to use IO salt, you should add some MG right into the new makeup water to bring it up when you are in maintenance mode.

Also its recommended to not increase the MG by more that 100ppm per day.

 

[calaxa]

+1 Phil

That test kit seems off or your testing is not correct. Try a new one. If you need to raise Mg in a hurry, Epsom salts/Mag Flakes will work. Remember what Phil said about 100ppm/day (though I know some people who have done a lot more without adverse effects *not what I suggest*)

 

[Hirobo]

I had the same problem when I used IO salt, it took daily dosing for about 2 weeks to get the level up and stay up but once I did a water change then I had to start dosing again. Someone told me they had the same problem with that salt and once they switched salts it went away. When I switched to RC salt it did, I now use TM pro.

That would be me Tom once i switched to reef crystals mine has been at 1500 without adding anything other than calcium every other week

 

[pgordemer]

I had the same problem when I used IO salt, it took daily dosing for about 2 weeks to get the level up and stay up but once I did a water change then I had to start dosing again. Someone told me they had the same problem with that salt and once they switched salts it went away. When I switched to RC salt it did, I now use TM pro.

That would be me Tom once i switched to reef crystals mine has been at 1500 without adding anything other than calcium every other week

A fresh batch of Reef Crystals made up to 1.026 will be at about 1260-1320 worth of MG. You can still use IO salt, just at 6 oz of MG suppliment for every 25 gallons made and it should get you close.

 

[mott768]

Mike, it wasn't you but I remember talking to you about it, it was awhile ago (at least 2 years) mine was the same way tho after switching I didn't have to add it, mine held at 1430 after a few water changes.

 

[Jon]

I tested my water this morning and it now read 1080. I added another 8 oz of magnesium and by tomorrow my levels should be ok. 8oz of Magnesium has been bringing my magnesium level about 200 points a day. I know this is a little bit risky but nothing seems stressed and all of my other water parameters are stable.

I have come to the conclusion that the salt I was using (Instant Ocean) is insufficient for my tank. I am going to upgrade the salt that I use for my next water change and hope that this will solve the problem.

Thanks for you input - Jon

 

[calaxa]

If you like IO salt, why not just do RC. Same company, usually only $2 more a bucket and has the trace chemicals you want. Still I find it odd IO salt would have such low Mg. I would imagine that IO had at least 900ppm Mg

 

[pgordemer]

Here are the CA/ALK/MG numbers for a lot of salts when mixed to 1.026. This is based on testing done by billybeau1 from the Reef Central Chemistry forum as was done in 2008. Billybeau1 is recognized as a leader in test kits analysis in that forum.

CA ALK MG
Aquatic Gardens 430 8 1240
CoraLife 560 9 1380
Crystal Sea Marinemix 340 9 1050
Crystal Sea Marinemix Bio-Assay 340 9 1050
D-D H2Ocean 450 10 1380
Instant Ocean 350 12 1070
Kent 540 11 1200
Marine Environment 480 7.5 1450
Oceanic 580 8.5 1650
OceanPure 510 10 1320
Red Sea 400 8 1300
Red Sea Coral Pro 490 7 1300
Reef Crystals 420 12 1260
Reefer's Best 420 11 1200
SeaChem Marine Salt 500 10 1400
SeaChem Reef Salt 540 10 1450
Tropic Marin 375 10 1230
Tropic Marin Pro Reef 450 8.5 1380
Tunze Reef Salt 420 9.5 1350

 

[Jon]

Thanks for the chart Phil. I think that I am going to go with KENT. They seem to have good "big three" levels and are priced in my range. Looks like I will making another trip to Aquarium Center soon.
Jon

 

[pgordemer]

Thanks for the chart Phil. I think that I am going to go with KENT. They seem to have good "big three" levels and are priced in my range. Looks like I will making another trip to Aquarium Center soon.
Jon

Do some research, these are just the big 3 numbers. Some of the salts that look high in something might have some other properties you don't want (like Boron). the other thing to consider is that some of the ones with high CA and MG numbers are so expensive, you could just by IO and add the additives yourself and save a lot of money. That is why Reef Crystals are very popular for reefers.

 

[Jon]

Phil once again thanks and I will look into this.

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[calaxa]

Someone else showed me that chart and I can tell you I don't get any of those numbers with RC or Oceanic. I get about 380 Ca and definitely not 12 dKH (more like 8). Phil do you have the original page where those results came from along with methodology, etc? I see it quoted all the time but want to see how it was arrived at and if there were multiple samples from each vendor, etc.

 

[mott768]

Someone else showed me that chart and I can tell you I don't get any of those numbers with RC or Oceanic. I get about 380 Ca and definitely not 12 dKH (more like 8). Phil do you have the original page where those results came from along with methodology, etc? I see it quoted all the time but want to see how it was arrived at and if there were multiple samples from each vendor, etc.

I wasn't going to say anything until someone else did ;D

Same here never got those numbers with RC or Tropic marin pro. TMP is close, Cal is closer to 430 and the mag is more like 1300, alk is right at 8

 

[calaxa]

Mott,

I got about that with TMP too but I cannot stomach paying 2x the price over RC for just a little more Ca.

 

[DaveK]

Here are the CA/ALK/MG numbers for a lot of salts when mixed to 1.026. ..

This is a good chart to start with. Note that several salts are very low in Mg and in Ca. I would avoid those. The trouble is that it's tough to pick a winner, because there are many other factors involved.

 

[mott768]

Mott,

I got about that with TMP too but I cannot stomach paying 2x the price over RC for just a little more Ca.

I'd still be using RC if it wasn't for receiving 2 bad buckets from Foster&smith I used RC for years until that happened. Supposedly they fixed the problem but after I lost some irreplaceable corals I won't switch back. To me paying extra for the salt is well worth it, it's tough to stomach yes but worth it. I learned my lesson