Magnesium neccessary additive?

[TheCheat]

So I was just reading up on dosing/additives and whatnot, and learned about Magnesium as a crucial element in the whole scheme of things.

My question is this: If I'm using water from a quality ro/di unit (let's just say, showing 0 TDS), and running a skimmer 24/7, will my salt mix contain the neccessary amounts of Magnesium to allow for Ca/Alk to be at proper levels? If not, why?

 

The reason I ask is that I see how a lot of folks have a Magnesium shortage, where other don't and just get by fine with dosing B-Ionic or something similar. Is the wildcard in all this the type of salt (IO, Crystal Sea, Tropic Marin)? Why do some people need Mg additives, and some dont?

 

Thanks all.

~B

[Cellenzweig]

Basically... if you can get your Cal and Alk up to appropriate levels, your magnesium is probably ok. If you're having trouble bringing Cal and Alk up, you should test for magnesium before adding any.

 

The reason some people need to dose magnesium and others don't is simply because every tank is different. It depends on many factors. Salt mix is definately one of them. Another is consumption. Depending on what is in your tank, the magnesium will be depleted at different rates. Type of skimmer also makes a difference. Some are "hard skimmers" and others, like the Euro-Reefs are "soft skimmers". I am probably not the best to define which is which and why, but basically, hard skimming strips the water of almost everything, whereas soft skimming leaves most of the essential elements in the water.

 

So the question should really be, "Is magnesium necessary for me?"

[TheCheat]

Thanks for the insight Cellen.

 

How many people out here find the need to dose Magnesium in one form or another? Are you running a skimmer and do you have lots of hard corals?

 

Thanks fellas.

B

[opihi]

I agree w/ Colin. it depends on the demands of your tank.

 

i had to dose Magnesium in my 50g holding tank after finding that my tank could no longer sustain CA up over 380. (SPS tank, 10g refugium w/ chaeto, 250w DE, reeftek CA Reactor, 5g water changes every 2 weeks)

 

before this tank, i never had to dose Magnesium at all (while still using IO). not sure if it was a bad batch of IO or what.

[bobioden]

It also depends on what salt you are using. When I was using Instant Ocean I had to dose Mg (Kent Tech M), after every water change. Along with Liquid Calcium. Since I swichced to Oceanic my Mg stays fine but I have to dose Baking Soda to keep my Alk in line. It all depends on what you have in your tank and how you tank uses these elements. I also swithced to Oceans Blend which is like B-Ionic and my levels are alot more stable. The only way to find out is to test.

 

Bob

[Undertheradar]

I dose it because I have a heavy SPS/clam load....and I dose all kinds of stuff to put off water changes (Im not telling how long its been since I did a water change). I dose trace elements, I use a fuge, skimmer, carbon, phos reactor, dose calcium like crazy (kent 2-part). Mg helps organisms absorb calcium. Its a required chemical for the reaction...forget what it is off the top of my head.

[kwl1763]

Agree with Undertheradar.

 

If you do water changes at least weekly with a salt that is adequate in MG. (I use Oceanic) it will be a non issue. If you don't do many water changes and have clams/SPS the mag will be depleted and you will most likely have to dose.

 

Most of the 2 parts have enough Mg to cover also so if you dose that you should be OK.

 

As always make sure you test before you do anything. Don't dose just because! As with most other elements having to much is toxic! Salifert has a very good MG kit.

[TheCheat]

Thanks for the info. I don't plan to dose for anything that isn't depleted. Just curious how many folks find themselves needing to do it for Magnesium. My concern is if it is particularly neccessary due to running a skimmer.

Thanks again,

B

[Undertheradar]

If you have a heavy SPS & clam content, you might benefit from it.