Do I need to add Magnesium?

[afboundguy]

From what I've gathered magnesium helps keep Calk and Alk in balance and is needed for coral growth, so I know I should keep an eye on it. But question is do I need to add any?

Current tank situation... (mainly softies and 2 LPS)

When I first started testing for Alk and Calc I had a reading of 500 for calc and 3 for Alk (the test kit said natural seawater has 4-5 but strive for 5-6. For the life of me I can't remember which measurement it was) At the time I was adding a liquid suplement that said it had everything.

I was advised to stop adding the supplement and bought a the Kent Tech CB part A and B to start adding once the Calc dropped. I also bought some Alk buffer to bring up the Alk while I dropped the Calc. So I stopped adding that to lower the Calc to 440-450 and it has been holding steady since I started testing (1-2 months I believe) I added the buffer the first day and re-tested and added re-tested as needed to get it up to 5-6. It seems that The Alk keeps dropping back down to 3. So I've figured out that adding some buffer every couple of days keeps the Alk up in the 5-6 range. But the Calc doesn't move no matter what I do with the Alk. I have yet to start adding the 2 part supplements because I don’t want to bring up the Calc.

So would magnesium be the problem with the falling Alk? I don't have a test kit and prob won't be able to get one for a while. I've read that in most tanks magnesium doesn't need to be added because it is replenished in the weekly (sometimes bi-weekly for me) water changes. For the record I use Oceanic Natural Sea Salt Mix that is supposed to have high Calc and Mag elements (which might be the reason that my Calc stays the same but not the Alk)

So what are everybody’s thoughts? I will eventually purchase a magnesium test kit but I'm still restricted in purchasing fish products because "we have to save for the wedding" and I promised her I wouldn't spend money on the tank... even though I've gotten permission to replace the 10K PC bulb, make a fuge, get a new skimmer pump, and get a green mandarin because they're all vital to the tank so who knows I might be able to convince her a magnesium test kit is vital

 

[ReeferMedic]

Short answer, don't add anything you haven't tested for. Things can get out of whack very quickly if you start adding things when you don't know what your levels are to begin with.

 

[MikeG]

Magnesium could contribute to the problem, some reading for you here.
http://reefkeeping.com/issues/2006-07/rhf/index.php

Also if looking to save some money, stop buying the alk buffer and use ordinary baking soda found in the grocery store(sodium bicarbonate)
http://www.reefkeeping.com/issues/2006-02/rhf/index.php#10

 

[marine mike]

IMO, and I am not nearly as experienced as some who will respond to you I am sure, I would say it sounds like everything is pretty normal. With mainly softies and LPS you will not get a tremendous amount of calcium usage, you will however have alkalinity usage. Magnesium is not used up heavily from what I have seen in my experience, and with regular water changes you should not have to supplement much if any. It doesn't sound like your alk is dropping too fast or outside of the norm for what you have in your tank. It also sounds like you are watching the right things and adding the right things. If you start to add more calcium consuming corals or critters (clams, etc.) then you might have to watch the ca and mag a little closer. Until then my advice is stay the course! I would also agree that there are cheaper ways to raise alkalinity than the buffer you are currently using.

 

[afboundguy]

Short answer, don't add anything you haven't tested for. Things can get out of whack very quickly if you start adding things when you don't know what your levels are to begin with.

I def second that... I would never add anything without testing after blindly adding the supplement that had "everything" and seeing the effects...

 

[afboundguy]

I would also agree that there are cheaper ways to raise alkalinity than the buffer you are currently using.

What else could I be adding? I just purchased the buffer because it was only supposed to be a temporary upping of the Alk while the Calc was dropping in range to the point where I could start using the 2 part supplement.

 

[afboundguy]

LOL I just re-read Mike G's post and saw that I can just add normal baking soda (which I thought we might be able to because when I worked for a pool company that's what you could do) I just saw that he put in links and didn't have time to read them so I just skimmed over it... DOOH!!!!!!

 

[MikeG]

LOL I just re-read Mike G's post and saw that I can just add normal baking soda (which I thought we might be able to because when I worked for a pool company that's what you could do) I just saw that he put in links and didn't have time to read them so I just skimmed over it... DOOH!!!!!!

Maybe I shouldn't post links

It explains the interaction between alkalininity, calcium, and magnesium in the first link. Randy has great articles that are very easy to read.

The second link is the recipe for the homemade 3 part additive in which baking soda is mentioned.

 

[delahunt]

salt adds mag

when you water change, the new salt you are using will also add mag

 

[afboundguy]

Thanks for those links... Great stuff... I just need to read better...