Low Mag yet high Cal...

J

john603

New member
Yesterday we tested our Mag to be around 1080 ppm and our Calcium was around 500... I remember reading that a low magnesium affects the formation of calcium carbonate (so low mag should inibit the ability to raise cal)... or something to that effect I can't remember off the top of my head.

Should I be concerned about the mag being so low? We just hooked up a pro-cal calcium reactor (two stages) about two weeks ago and it seems to be working great. Calcium before was always around 420-450 (depending on how frequent/regular we were at adding the kalkwasser powder) and our dKH is around 12.5

Any help would be appreciated... Thanks.
 
incorrect measurement possible on the mag reading?

It's a risky situation in that you could get a sudden precipitation of calcium carbonate. I'd stop dosing calcium for a little while and just add a magnesium--I use the Seachem crystals

(mag supplies a bonding mechanism for calcium carbonate so that you can over saturate the calcium---without the mag the calcium carbonate would precipitate out.)
 
Those measurements are reasonable. I'd raise magnesium to 1300 ppm, though, over a few days. That should help prevent snowstorms on accidental overdoses, and perhaps reduce abiotic precipitation a bit.
 
I'll do another barrage of tests tomorrow after disabling the calcium reactor for the time being.

I'm sure it's a highly debated topic, but what do y'all suggest for magnesium dosing?
 
I like seachem's magnesium... but to raise your mag (300g) up 200 mg/dl is going to take about 600 teaspoons...
 
Since corals also take up magnesium in their skeletons,if your magnesium is low will it discourage calcification and thereby reduce the use of calcium by the corals?
 
I wouldn't use SeaChem's magnesium, since it's basically just epsom salts. Kent Tech-M and ESV are fine, in my experience, and Salifert and Warner should be okay as well. I use a DIY mix, currently.

If magnesium is low enough, calcium and alkalinity will be hard to maintain. I think that would happen before corals have problems with low magnesium directly.
 
epsoms is fine for occasional use, I just would not use it for long term management. it is uber cheep.. ~$3.00 for 1/2 gallon at any drug store and most grocery stores, in a 100 gal reef that should add ~ 500ppm, DON'T DO IT ALL AT ONCE :(
 
Re: Low Mag yet high Cal...

<a href=showthread.php?s=&postid=10760207#post10760207 target=_blank>Originally posted</a> by john603
Yesterday we tested our Mag to be around 1080 ppm and our Calcium was around 500... I remember reading that a low magnesium affects the formation of calcium carbonate (so low mag should inibit the ability to raise cal)... or something to that effect I can't remember off the top of my head.

Should I be concerned about the mag being so low? We just hooked up a pro-cal calcium reactor (two stages) about two weeks ago and it seems to be working great. Calcium before was always around 420-450 (depending on how frequent/regular we were at adding the kalkwasser powder) and our dKH is around 12.5

Any help would be appreciated... Thanks.
Click to expand...

John,

I would try and get your mag up to between 1250 and 1350. This will help you control cal and alk. You may need a supplement like Kent's Tech-M or the diy to get you there.

Just use the Chemicals calculator to determine dosage.

I'm wondering what salt mix you use ? :)
 
<a href=showthread.php?s=&postid=10763415#post10763415 target=_blank>Originally posted</a> by bertoni
I wouldn't use SeaChem's magnesium, since it's basically just epsom salts. Kent Tech-M and ESV are fine, in my experience, and Salifert and Warner should be okay as well. I use a DIY mix, currently.

If magnesium is low enough, calcium and alkalinity will be hard to maintain. I think that would happen before corals have problems with low magnesium directly.
Click to expand...

gee Jonathan--why didn't you tell me that before---i'll switch it out to Kent Tech-M :eek1: :rollface:
 
More measurements:

Pre-reactor w/ daily kalkwasser supplements
Ca ~ 450
dKH ~ 6 (just before reactor install, w/ few measurements prior)
rest of readings were fairly normal, we weren't recording anything and the tank has been running for about 6 months now

Post-reactor (8/30 and on):
8/31: Ca 440, pH 8.5, dKH 8, phos 0.25, I ~ .06
9/5: pH 8.0, dKH 10
9/9: Ca 495, pH 8.5, dKH 11
9/11: pH 8.5, dKH 12.5, mag 1080
9/13: killed some apistasia with Joe's Juice and did a 10% water change
9/14: Turned off Ca reactor, Ca 470, mag 1080, dKH 11, pH 8.4, added approximately 5 oz of Kent Tech-M

sg has been 1.023-1.024 using Tropic Marin salt

I was wondering about the validity of the salifert mag test we were using, so we did a test on a fresh batch of salt mix @ 1.024 and it read 1250...
So we went ahead and bought 2 gallons of Kent Tech-M (way cheaper online after buying a 16 oz bottle at a LFS btw...). I guess we'll be adding this over the next two weeks...
 
Sounds reasonable. You might want to turn off the reactor for a bit and let calcium drift down while maintaining the alkalinity with baking soda. A dKH of 11 is okay, but I'd let calcium drop to 450 or perhaps even 400 ppm.
 
<a href=showthread.php?s=&postid=10769281#post10769281 target=_blank>Originally posted</a> by capn_hylinur
wouldn't it also be adventageous to bring that salt level up to .026?
Click to expand...

When I used to read a lot of reef central (over a year ago) I thought the consensus was .024 was the more ideal target?
 
There's a lot of discussion about SG. 1.0264 is the canonical average sea water, and that's what I target. I don't see any reason to go lower, but 1.024 probably isn't harmful. There are a lot of articles on SG, if you're interested in some reading.
 
IMO--alot is being implied here
3 months ago---I reported pH 7.7-7.9 the guys said probably isn't harmful--but 8.2 is closer to canonical average
I reported alk at 8.2------ditto---10.6 would be better
I reported temp 78------dittto ---80 would be better
I reported calc 400---ditto----450 would be better
People have noticed remarkable improvement in my tank--my LPS's are on fire---Iwas barely getting any growth for six month--great now

It doesn't hurt to airm for what these experienced tell you :)
 
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