Why is my Mg always so low?

[c_scherer123]

I have had my 20g for about 8-9 months. I have perpetually low Mg, even though I dose it bi-weekly or more often. The fresh salt batches come in at 1400 mg.
Calcium is 500
Magnesium is 900

I can tell when my magnesium is below 1200, as all my polyps (especially the GSP) and torch corals close up.
I did notice that the coraline algae is starting to grow all over the rocks and glass. I removed the small bit of chaeto I had and that noticeably helped keep the MG level steadier.

Any ideas?

[fishytime]

whats your DKH at?.....those three (Ca, Mg and DKH) need to be balanced....my guess is your having trouble raising it because of an imbalance in your other parameters.....

[The Grizz]

My Mg is low as well but my Ca is a 480 and DKH is at 8.5. Tested Mg last night and it was 1150.

[Jason McK]

Are you sure when you first mix the SW for a water change it's at 1400? What salt are you using

[c_scherer123]

I will check DKH and salt names when I get home.
Last time I checked, the DKH was fairly high (unusually so), but so it is also high in my fresh salt mix.

[Delphinus]

Dumb question but I'll ask it anyhow .. when you're dosing Mg, are you dosing it to bring it back to 1400 or are you dosing the amounts suggested on the bottle? Oh wait, IS there a bottle? What are you dosing for Mg?

Here's my take. Mg is an underappreciated element by the powers that be within the hobby. Commercially available Mg to dose is like taking a peashooter to a shootout where the other gunslingers are carrying Uzi's (Ok my metaphor sucks, but I'm too lazy to think of something else. I use the "it's like draining a lake with an eyedropper" metaphor far too often and it's time to shake things up a bit). I would buy a $30 bottle of Mg solution from the LFS and then end up dumping the entire bottle into my water change water to make it 1400. So now I just buy 20-30 lbs. of MgCl crystals from LittleSilverMax because it's a far more cost effective solution, costs me maybe $80 or whatever but I end up with enough to fill a 5g salt bucket which lasts 6 to 12 months. I end up adding 225ml of it (almost a full cup) to my makeup water to make 1400 and when I dose my tanks I found it surprising how much of it I would need to raise Mg by 100. I forget how much exactly (I write stuff like that down so that I don't need to remember it, consequently, I don't remember what it is when I'm writing a post like this. Sorry. :redface:)

So if you're using a commercially available product to dose Mg and just following the instructions of "one capful per X gallons", my bet is that this is just not enough to maintain Mg. It wasn't for me anyhow and I'd be surprised if that truly works for anyone.

Over time Mg will deplete just like Ca and Alk will. Think I've heard the addage that the depletion rate is roughly the same per week as it is for Ca or Alk per day.

[c_scherer123]

Dumb question but I'll ask it anyhow .. when you're dosing Mg, are you dosing it to bring it back to 1400 or are you dosing the amounts suggested on the bottle? Oh wait, IS there a bottle? What are you dosing for Mg?

Here's my take. Mg is an underappreciated element by the powers that be within the hobby. Commercially available Mg to dose is like taking a peashooter to a shootout where the other gunslingers are carrying Uzi's (Ok my metaphor sucks, but I'm too lazy to think of something else. I use the "it's like draining a lake with an eyedropper" metaphor far too often and it's time to shake things up a bit). I would buy a $30 bottle of Mg solution from the LFS and then end up dumping the entire bottle into my water change water to make it 1400. So now I just buy 20-30 lbs. of MgCl crystals from LittleSilverMax because it's a far more cost effective solution, costs me maybe $80 or whatever but I end up with enough to fill a 5g salt bucket which lasts 6 to 12 months. I end up adding 225ml of it (almost a full cup) to my makeup water to make 1400 and when I dose my tanks I found it surprising how much of it I would need to raise Mg by 100. I forget how much exactly (I write stuff like that down so that I don't need to remember it, consequently, I don't remember what it is when I'm writing a post like this. Sorry. :redface:)

So if you're using a commercially available product to dose Mg and just following the instructions of "one capful per X gallons", my bet is that this is just not enough to maintain Mg. It wasn't for me anyhow and I'd be surprised if that truly works for anyone.

Over time Mg will deplete just like Ca and Alk will. Think I've heard the addage that the depletion rate is roughly the same per week as it is for Ca or Alk per day.

I first bought the liquid stuff, but I found it pretty useless, so I am now using crystals http://www.petsandponds.com/en/aquarium-supplies/c6653/c263452/p17157180.html. I didn't find out about Littlesilvermax until after I bought the big container. I dose a max of 1 tbsp per day to avoid shocking my corals (who told me they disapprove of larger MG swings). I generally dose 2-4 days per week.

[fishytime]

Try using this http://www.reeftime.com/reef-chemistry-calculator.asp ....it will tell you what you need to dose of each chemical to get your parameters balanced

[kien]

Your Calcium is 1500ppm ?? Wow, I have never seen anyone run calcium that high. Is that just how it comes out in your Salt Water mixes or do you dose to get your Calcium to that level?

[Delphinus]

Oooh ... good catch Kien. Calcium can't be 1500 that sounds way too high. I thought you meant 500 which is still quite high but not impossibly so. As for adjusting Mg you should be able to adjust by 100 per day, when I target Mg in my tanks I'll go whatever amount gets me a 100-150 rise in Mg and then just repeat that daily until I've hit 1400.

[whatcaneyedo]

Heres tonights optional reading.

Do-It-Yourself Magnesium Supplements for the Reef Aquarium
http://reefkeeping.com/issues/2006-07/rhf/index.php

Magnesium in Reef Aquaria
http://www.advancedaquarist.com/issues/oct2003/chem.htm

A Simplified Guide to the Relationship Between Calcium, Alkalinity, Magnesium and pH
http://reefkeeping.com/issues/2006-06/rhf/index.php

[c_scherer123]

Your Calcium is 1500ppm ?? Wow, I have never seen anyone run calcium that high. Is that just how it comes out in your Salt Water mixes or do you dose to get your Calcium to that level?

Good catch, it is a typo, I meant 500.

Salt is a mixture of "marine environment - superior two part" and "red sea coral pro salt". Each one has what the other tends to lack and so it balances out pretty well.

As for KH reading, after getting an absolutely ridiculous reading (50 - the test tube was almost full!), I checked the exp. date and it is 6 yrs past it. Just bought that kit in April too... Used it 3-4 times with KH always high around 10-12.

I also dose Kalk, and occasionally 2 part, with all RO water added. My calcium always used to be around 400 even with the dosing, and suddenly its stopped dropping.

I don't suppose that a bottle of tank water would last a 4 hour trip into the city and that the water values would remain unchanged? I might as well get the pet store to check it as well as buy a working test kit, at least then I will know if my other kits are working (all other exp. dates are looking good).

I am pretty sure it is an imbalance as suggested, I just need to figure out how the balance currently sits.

[c_scherer123]

Heres tonights optional reading.

Do-It-Yourself Magnesium Supplements for the Reef Aquarium
http://reefkeeping.com/issues/2006-07/rhf/index.php

Magnesium in Reef Aquaria
http://www.advancedaquarist.com/issues/oct2003/chem.htm

A Simplified Guide to the Relationship Between Calcium, Alkalinity, Magnesium and pH
http://reefkeeping.com/issues/2006-06/rhf/index.php

Thanks for the great links!

[The Grizz]

I have been trying to find out where to get the MAG FLAKE's. Could some one please tell me what they are using for the MAG FLAKE'S, I know that Epson Salts is part one.

[whatcaneyedo]

Someone said that they were able to get their city's Home Hardware to special order them a bag of Mag Flake. If that doesnt work for you, you can buy pharmaceutical grade magnesium chloride hexahydrate (spelling?) from Bulk Reef Supply or chemmaster (who's is already mixed with magnesium sulfate). I personally use a non-pharmaceutical grade ice melting salt called Absolute Zero Melt Down which is 100% magnesium chloride hexahydrate(?). So far I have not had any problems with it *knock on wood* and it only costs $25 for a 30 lbs bag.

[the marine apprentice]

when you are mixing the first part with the second part how much of each would you use? for say a 5gallon pail of fresh RO water

[whatcaneyedo]

According to the first article mix the two together 7.1:1 (chloride:sulfate) if you like to measure by weight or 10:1 by volume. When I do my weekly 10% water changes I just add 1 cup of the mix per 10gal of water change water. Magnesium in my tank has been sitting between 1400 and 1500ppm for the past year by doing that.

[The Grizz]

Someone said that they were able to get their city's Home Hardware to special order them a bag of Mag Flake. If that doesnt work for you, you can buy pharmaceutical grade magnesium chloride hexahydrate (spelling?) from Bulk Reef Supply or chemmaster (who's is already mixed with magnesium sulfate). I personally use a non-pharmaceutical grade ice melting salt called Absolute Zero Melt Down which is 100% magnesium chloride hexahydrate(?). So far I have not had any problems with it *knock on wood* and it only costs $25 for a 30 lbs bag.
What store did you find the Absolute Zero at?

[whatcaneyedo]

I bought Absolute Zero from Amco Wholesale but they only exist in PG. You can try contacting the maker of Absolute Zero, Envirotech, to see if they have any distributors in your area.

A word of warning though, I contacted them before I began using the product to see what they thought about it being added to an aquarium. Their recommendation was that it should not be used because their manufacturing process does not meet pharmaceutical grade standards and there is a possibility for contamination. On a related note the manufacturer of Mag Flake also does not recommend its product be used in this way. It would cost me roughly $4 more per pound to purchase pharmaceutical grade so I am willing to take that risk.

BTW have you ever noticed that there is a warning on the Q-Tips box not to insert them into your ear canal? Companies just dont want to be sued.

http://www.amco.bc.ca/home.html
http://www.envirotechservices.com/meltdown-absolute-zero/

[The Grizz]

Well I cant find any where in Red Deer that has magnesium chloride hexahydrate . So I might have to order from Bulk Reef Suplies.

[the marine apprentice]

greg if ya want to do an order im sure i will be in with ya. i want to try this out

[Delphinus]

Why not order from ChemMaster? He's Canadian. Stuff is premixed so it's just scoop and go.

http://www.canreef.com/vbulletin/showthread.php?t=26590

[The Grizz]

Why not order from ChemMaster? He's Canadian. Stuff is premixed so it's just scoop and go.

http://www.canreef.com/vbulletin/showthread.php?t=26590
That make more sence, thanks Tony

[The Grizz]

Terry I will do some research into how much I might need for the new tank, find out how much shipping is and let you know

[Coleus]

Try using this http://www.reeftime.com/reef-chemistry-calculator.asp ....it will tell you what you need to dose of each chemical to get your parameters balanced

I have a question about the calculator and dosing mag.

Let's say my tank is 180 gallon in total (main + sump) and i am using Sea Chem Magnesium Advance and I would like to raise from 1300 to 1400

The calculator says the amount i need is 171 tsps; 855 grms; 30.15 oz


So, do i pour this whole amount into 10% of freshwater change or directly into the tank? Raising 100ppm per day is safe right?

Thanks

[e46er]

Don't forever to account for sand and water rock displacement