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Need chemistry refresher course

HUMBLEFISH,,
Hey I’m lil stuck on my order of what helps what,, my mag is lil high at 1440-1480 and at my last test it was 1360-1400,, and only other change was my ALK which went up a touch last test was 6.4-6.7 now I’m at 7.0-7.3 my pho’s is same at 0.33 and cal is same at 400 nitrates are 2.00-4.00
So I guess my question is how do I get mag down
 

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Mark_C

Staff member
Officer Emeritus
NJRC Member
Moderator
Soz, not HF, but can supply a generic answer.
If your going to worry about and chase parameters, which is a habit that can never end, the two you should be most concerned about are Ca and Alk. Mg will fall in line. I wouldn’t worry about the Mg at all, especially if your not growing sps.
Calcium should be around 420ppm in a system that has corals that grow skeletons.
Magnesium bonds with calcium (carbonate) to build those hard coral skeletons as needed so levels will fluctuate. If you dont have any sps or hard corals using it, it will run a bit high.
Alk is not a thing, its a measure of the overall chemical balance of the system. It should be anywhere between 7 and 11. The higher the number the more bicarbonate and things are in the water and the more reactions occur. Again this should be higher for sps and hard coral tanks.
Theres a load of people, myself included, that consider monitoring thre Alk as most important. I'm mostly soft corals with a few sps, so I keep my alk at around 8, which also means that my calcium and magnesium should balance around that number on their own and there really isn’t a need to be chasing stuff.
I just added a bunch of hard coral today, now I'm going to bump up my alk to around 9.
In my soft only tank, I've no real concern for Ca or Mg, as I have 0 hard corals, so I keep the alk around 7.
Sit back, chill, look at your tank and relax. The tank will let you know if something is wrong.
 
Soz, not HF, but can supply a generic answer.
If your going to worry about and chase parameters, which is a habit that can never end, the two you should be most concerned about are Ca and Alk. Mg will fall in line. I wouldn’t worry about the Mg at all, especially if your not growing sps.
Calcium should be around 420ppm in a system that has corals that grow skeletons.
Magnesium bonds with calcium (carbonate) to build those hard coral skeletons as needed so levels will fluctuate. If you dont have any sps or hard corals using it, it will run a bit high.
Alk is not a thing, its a measure of the overall chemical balance of the system. It should be anywhere between 7 and 11. The higher the number the more bicarbonate and things are in the water and the more reactions occur. Again this should be higher for sps and hard coral tanks.
Theres a load of people, myself included, that consider monitoring thre Alk as most important. I'm mostly soft corals with a few sps, so I keep my alk at around 8, which also means that my calcium and magnesium should balance around that number on their own and there really isn’t a need to be chasing stuff.
I just added a bunch of hard coral today, now I'm going to bump up my alk to around 9.
In my soft only tank, I've no real concern for Ca or Mg, as I have 0 hard corals, so I keep the alk around 7.
Sit back, chill, look at your tank and relax. The tank will let you know if something is wrong.
That’s the greatest answer I could ever want,, nice
Thanks mark
 

Humblefish

NJRC Member
Article Contributor
I don’t worry about elevated mag. I’ve gotten it as high as 1700-1800 in an acro dominated tank and didn’t see any negatives. Alkalinity I like to keep between 8-10 dKH and calcium around 450-500 ppm. You just never want your calcium level to get too high, or you will see precipitation and that can damage your pumps.
 

Bot587

NJRC Member
paulie are you absolutely sure those are your readings?
1440 would usually suspend higher Ca ions (450 ish) and higher alk (10 ~9.5-10.5dkh)
 

Bot587

NJRC Member
better question, do you have any precipitate at top of tank or in sump (white powders/calcification)
If so, numbers are prolly wrong
 

Bot587

NJRC Member
well the fact that theres no calcification does help support the low alk/cal vs high mag (do you check pH?)

What salt brand do you use? (only a couple brands go to 1400+ Mg)

Do you dose magnesium? (You could have raised it yourself - it would take a lot of BRS or Red Sea C to do that)

Do you have a lot of Coraline? (Coraline is one of the main ways Mg is pulled from your water - new tanks generally don't lose Mg without coraline/other things)

Is your water 0 TDS - Na and Mg are the first two trace metals in water to slip through on Chloride ions

I promise there is a method to my madness
 
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well the fact that theres no calcification does help support the low alk/cal vs high mag (do you check pH?)

What salt brand do you use? (only a couple brands go to 1400+ Mg)

Do you dose magnesium? (You could have raised it yourself - it would take a lot of BRS or Red Sea C to do that)

Do you have a lot of Coraline? (Coraline is one of the main ways Mg is pulled from your water - new tanks generally don't lose Mg without coraline/other things)

Is your water 0 TDS - Na and Mg are the first two trace metals in water to slip through on Chloride ions

I promise there is a method to my madness
I don’t use salt or RODI water, all ocean water 100% tank is young 4 months maybe 5
 
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