Why won’t my Mg increase?

[DoctaReef]

Does anyone have an idea why my Mg won’t increase despite dosing it daily? It seems to be stuck between 1225 and 1255.
I’m measuring it with an Apex, and if I test the calibration solution it gets an accurate reading.
It’s a Red Sea reefer 425, about 100-110 gal including the sump.
My parameters are in the photo from the Apex.
I dose tropic Marin A,B and C for Alk and Ca. Apex does it all.
For Mg I’m adding Red Sea, 30 ml per day.

Thoughts?

 

[Lavey29]

Probably because your salinity is slightly low. There is no way you should be adding 30ml per day of magnesium. Your probe is faulty.

 

[HudsonReefer2.0]

Did u chk that reading with another test? And why are u dosing?

 

[Randy Holmes-Farley Verified Community Expert]

Did you calculate what mag boost you’d expect to see from that dose?

How long have you been dosing it?

 

[Uncle99]

I only dose 6ml Red Sea daily to maintain 1400ppm mg in 200gallons and heavy SPS load.

 

[DoctaReef]

Probably because your salinity is slightly low. There is no way you should be adding 30ml per day of magnesium. Your probe is faulty.

Which probe? It’s a trident. Ca and Alk are similar to the calibration solution I used when I switched the reagents last time.

 

[DoctaReef]

Did you calculate what mag boost you’d expect to see from that dose?

How long have you been dosing it?

Red Sea part c says 1 ml per 25 gal should raise it by 1ppm.
100 gal: 4 ml should raise 1ppm.
30ml/day should raise it by 7.5 ppm/day right?
Dosing for 10 days- should have seen a 75 ppm increase. But I’m not seeing any effect at all.
Wondering if there’s a chemical reaction occurring I don’t know about?

 

[DoctaReef]

I only dose 6ml Red Sea daily to maintain 1400ppm mg in 200gallons and heavy SPS load.

I’m trying to increase from 1225 to 1400, so I’ll need more.

 

[DoctaReef]

Did u chk that reading with another test? And why are u dosing?

I’ve got an ICP out. Just got to triton today.

 

[Lavey29]

Which probe? It’s a trident. Ca and Alk are similar to the calibration solution I used when I switched the reagents last time.

Ok, didn't read initial post clearly. Magnesium typically depletes at 1/10 th the rate of alk and cal. Weekly water changes usually replenish any Magnesium that has depleted. Sometimes weekly dosing a small amount is needed between water changes. Something is off with your trident reading. There is no way you need 30ml of Magnesium dosing per day. Get a second test method to confirm your number and check it over a 3 day period to see if you show depletion. I dose 15ml of red sea Magnesium weekly in between water changes.

 

[Randy Holmes-Farley Verified Community Expert]

Wondering if there’s a chemical reaction occurring I don’t know about?

Nope. Most likely, test error, but an adulterated batch of product is possible.

 

[DoctaReef]

Nope. Most likely, test error, but an adulterated batch of product is possible.

ICP should come back tomorrow- I’ll compare and see.

 

[rishma]

ICP should come back tomorrow- I’ll compare and see.

We are all interested to know! Glad you sent an ICP. My money is on test error.

 

[Uncle99]

I’m trying to increase from 1225 to 1400, so I’ll need more.

To bring it up, sure. But after that, 30ml is 6x what you’ll need to maintain.

I too was surprised how much product I needed to use at first, but I did get there.

You can just dose 5-6ml day of MG, and then 30ml once per week until you reach whatever level you want.

No need to rush any change for just MG.

 

[KrisReef]

I’m trying to increase from 1225 to 1400, so I’ll need more.

7.5 / 1225 = 0.00612244898

1225 / 1232.5 = 0.993914807 (Rounds up to 1) = No change detectable

You can safely dump in 100 mls and remeasure and you may still not see a bump. This is (what I understand) the reason why Mg is so difficult to measure in our tanks.

 

[Merge_595]

I'm on my 3rd trident & my Cal & Mag have always been at least 20ppm off from ICP I always take a screenshot the day I send out icp. Leaned the hard way was dosing a ton of Mag because trident wasn't going up also..when I got ICP back it was 100ppm higher than trident(years ago)

 

[rishma]

ICP should come back tomorrow- I’ll compare and see.

What did ICP say?

 

[BryanM]

I'm also thinking test error. ICP will help confirm.