how to keep Magnesium under control?

Groundfury

T. B. R. C. Member
I have been battling trying to keep my mag up to the 1300+ range, every time i do a water change to drops back down to the 900 range and I spend the next week or so getting it back up to start all over again. I have switched back to reef crystals hoping with this help some.

I'm dosing 45ml of 2 part a day and my levels seem to be ok Cal low 400's and ALK 8-9. so the question come down to show i worry about it and if so any clues on how to keep it up in range? I'm tested with Salifert mag kit.
 

kkdoughboy

New member
I hear ya partner. I test with Sera and use Reef Crystals and pretty much every three days my MG goes from 1350 down to 800-900. I recently started dosing MG with Brightwell Powdered Magnesium supplement. Tagging along on this thread. Hope someone can help
 

killerbee181

Here fishy fishy!
make sure your mag levels are already at your desired levels in the new saltwater otherwise when you do a water change it will dilute the mag and lower it. You should do the same with your cal and alk.
Terry
 

boring

New member
i keep brightwell neomag in a filter bag in the sump and mine stays up all the time, in fact i had to back off the amount i had in there because it was getting to high, also as posted above the water your puting in need to be the same as whats coming out,
 

plc001

Premium Member
Re: how to keep Magnesium under control?

Wow, from 1300+ to 900 in one water change????? That is a lot. How much water are you changing? Mag should be pretty constant. Even if your new water was at 0, which it will not be, do not see how it can drop that much.

Have you double check your test kit?

<a href=showthread.php?s=&postid=15486967#post15486967 target=_blank>Originally posted</a> by Groundfury
I have been battling trying to keep my mag up to the 1300+ range, every time i do a water change to drops back down to the 900 range and I spend the next week or so getting it back up to start all over again. I have switched back to reef crystals hoping with this help some.

I'm dosing 45ml of 2 part a day and my levels seem to be ok Cal low 400's and ALK 8-9. so the question come down to show i worry about it and if so any clues on how to keep it up in range? I'm tested with Salifert mag kit.
 

sedor

New member
I agree, lets say you change 15G on a 150, thats still only 10% meaning that if your Mg was at 1300 it should technically only drop to 1170 and thats if your WC H2O was at 0.

Unless you have something thats using it up like crazy, but I kind of doubt that. I would dose enough to get it to where you want it, and then make sure you also dose your WC H2O.
 

Groundfury

T. B. R. C. Member
Ok so i tested my change out water and the mag is setting in the low 900's so I ran some number at BRS and to bring my tank from 900ppm to 1300ppm I need 196oz of mag, my 30gal of change out water I need 32oz. Are you guys really using that much mag on a weekly bases?

What are you guys using for mag? I see some are using brightwell what else are you guys using?
 

ahayes13

New member
i use tropic marin bio mag... and love it. i dose my new water that im going to do the water change with. i end up using 4 spoons per 5 gallons of water. i like the bio mag cause it gives me constantly accurate results.
 

mflamb

New member
Recheck your procedures.
Test Mg in tank water.
Test Mg in water change water.
Dose the appropriate amount of Mg to water change water to bring it up to match tank water.
Do water change.
Test Mg in water change water. Should be ok.
 

Groundfury

T. B. R. C. Member
Re: Re: how to keep Magnesium under control?

Re: Re: how to keep Magnesium under control?

<a href=showthread.php?s=&postid=15488148#post15488148 target=_blank>Originally posted</a> by plc001
Wow, from 1300+ to 900 in one water change????? That is a lot. How much water are you changing? Mag should be pretty constant. Even if your new water was at 0, which it will not be, do not see how it can drop that much.

Have you double check your test kit?

I have not been able to get it up to the 1300+ range yet but that is my target, I only get to high 1100 low 1200 before i have to do a water change. I was doing 20 to 30 changes every week, this is my first week of going two week between changes to see if that helps.
I have not checked my test kit with another but i do test my biocube and it's always spot on.

plc001 I am using the same recipe as you are.
 

boring

New member
on other thing is do you dose Ca?? i ask because the reason you are dosing Mag is to get you Ca up right?? well when you dose Ca it binds to the Mag and will bring it down some, what is the Ca level on the water change water?? if the Mag is only 900 but the Ca is like 400-450 then thats could why your Mag is going down, after the WC
 

Groundfury

T. B. R. C. Member
<a href=showthread.php?s=&postid=15490014#post15490014 target=_blank>Originally posted</a> by boring
on other thing is do you dose Ca?? i ask because the reason you are dosing Mag is to get you Ca up right?? well when you dose Ca it binds to the Mag and will bring it down some, what is the Ca level on the water change water?? if the Mag is only 900 but the Ca is like 400-450 then thats could why your Mag is going down, after the WC

I will test the Cal level of my water change when i get home tonight, I just made a batch last night for this weekend.

oldstaint: thanks for the FYI that makes be feel a little better, I read all over that you want to keep you mag at 1300+ but i do not remember reading that a 3x to cal is balanced. With my Cal in the low 400's getting my mag to 1100 to 1200 not so bad.
 

oldsaint

Just me
Premium Member
oldstaint: thanks for the FYI that makes be feel a little better, I read all over that you want to keep you mag at 1300+ but i do not remember reading that a 3x to cal is balanced. With my Cal in the low 400's getting my mag to 1100 to 1200 not so bad.
I've read it in a couple of places. Still looking for the links. Sorry, lost a bunch along with pics when my computer crashed. I do have this one still saved that covers it some what.
http://www.advancedaquarist.com/issues/oct2003/chem.htm
In full strength seawater (S=35), magnesium is present at approximately 53 mM (mM is short for millimolar, which is a measure of the actual number of ions present, as opposed to ppm (parts per million), which is a measure of the mass of ions present). Only sodium (469 mM) and chloride (546 mM) are present at higher concentration, with sulfate (28 mM) following close behind. Magnesium is about five times more abundant than calcium (10 mM). Magnesium is significantly lighter than calcium, so when compared on a weight basis, it is only about 3 times as concentrated (1285 ppm vs. 420 ppm).
 
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