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Discussion Starter · #1 ·
Hey Guys,
I am the owner of a 29G Biocube tank. I have a 2 in plus live sand bed, dry live rock, 1 blue banded crab, 13 blue tip crabs, 2 turbo snails. That is all that is in my tank it has been up for about 5 months. I Have been using RO/DI water. I always have a zero reading for the following tests: Phosphates, Ammonia, Nitrates, Nitrites. My Ph is typically at 7.7 to 7.8, I like for that to be higher. I have had a terrible problem with calcium, magnesium.
I have fixed most of the problem. Like i said before my levels are all normal except Magnesium. My calcium level is at 440 after my water change. My ph was 7.7 to 7.8 and all other reading were zero. the KH was within perfectly normal range. My magnesium level however was at a reading of 400, EXTREMELY LOW. no matter what i do I can't seem to get this up. there is no coral or algae in my tank my snails and crabs have eaten it all up. There was brown Diatom but that is all gone. I am unable to get anything to put in my tank because of this problem.
I have not added any PH buffers, or calcium supplements. I can add a crap load of Magnesium supplement to my tank and it never changes anything. There is nothing in my tank that would need that much magnesium. Where is it all going? Someone please help. I want to know why my chemistry is off. If my calcium levels are normal, and everything else reads normal why is my magnesium constantly staying low.:bawling:
 

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Discussion Starter · #3 ·
yes they tested it at well the magnesium just never goes up or goes up to a normal level and over night drops way back down again
 

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What do you mean by " I have had a terrible problem with calcium, magnesium.
I have fixed most of the problem."? If you are having a problem with maintaining levels, it is most likely due to precipitating due to the low magnesium.

How are you doing for all levels? Kalk? 2-part?

I'm by no means an expert on this, but what is the magnesium of your water change water? I'm thinking it is so low, that it is getting absorbed in the process faster than you are adding it.

Here is an excellent link to understand the processes:
reefkeeping.com/issues/2006-06/rhf/

On magnesium:
.advancedaquarist.com/2003/10/chemistry#section-3
 

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Have you tested the levels in your fresh saltwater before it's added to the tank during your water changes?
 

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Having low magnesium makes it very hard to keep calcium and alkalinity levels stable. Are you seeing any precipitate on equipment or along the water line? Also, what salt are you using? wcarterh already posted the reefkeeping.org link I was going to post. It is a great read. This article helps relate Mg use to Ca and Alk use, it might help you get a better big picture of whats doing on here.
 

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What are you using as a magnesium supplement?
 

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Discussion Starter · #8 ·
Okay so I think I have figured it out. I did a 50% water change and did a 20% change this morning really early at 6:00 and the calcium level is at 440 and the magnesium level is at 1400. Those are both a little high I was always told that it was suppose to be 420 for calcium and 1350 for Magnesium. I have white flakes in the water now. Like the size of a sugar granual. I am going to turn my protein skimmer up to see if it will get it out of the water. Any suggestions on what it is and how to get rid of it. THank you guys for all your help
 

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Your mag should be roughly 3 times your calcium level. With your calcium at 420, your mag should be roughly 1260.

Check out this calculator: http://reef.diesyst.com/chemcalc/chem_calc3.html

It never steered me wrong.

The flakes you have in the water is likely the calcium or mag precipitating out of the water. One of them is too high. I'd have your water tested at a LFS again to verify your test kit results.
 

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I don't really think your calcium is high. I've kept mine at that level without issue. The magnesium is high but will drop with water changes and time.
 
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