Magnesium inconsistency

[A Toadstool Leather]

I tested both calcium and alkalinity with salifert test kits. My calcium came out to be 370ppm and magnesium 1100ppm. Is the magnesium reading wrong? Can the magnesium be that low while calcium is within near normal levels?

 

[Caseyoidae]

Yes. Depends on salt you are using and coral consumption. That's about right when you think about the numbers percentage wise. cal would be 8% low if you are shooting for 420 and mag would be 6% low if you're shooting for 1320 (edit take my math with a grain of salt )

 

[A Toadstool Leather]

Yes. Depends on salt you are using and coral consumption. That's about right when you think about the numbers percentage wise. cal would be 8% low if you are shooting for 420 and mag would be 6% low if you're shooting for 1320 (edit take my math with a grain of salt )

I guess I will just increase mg and hopefully the ca will sort itself out. Its just odd since most of my corals are soft corals. I have a plate, duncan, and I recently added a brain and cup coral. My tank is 30 gallons btw

 

[Caseyoidae]

I'd dose both. It's kind of a dose and test game until you find the perfect amount for daily dosing. There are reef calculators and " x amount will raise mag in 1 gallon such and such and amount " on most additives but every system is different. Plates and Duncan's are stony corals that will benifit from the addition of calcium. I wouldn't worry to much about it with regular water changes

 

[A Toadstool Leather]

I'd dose both. It's kind of a dose and test game until you find the perfect amount for daily dosing. There are reef calculators and " x amount will raise mag in 1 gallon such and such and amount " on most additives but every system is different. Plates and Duncan's are stony corals that will benifit from the addition of calcium. I wouldn't worry to much about it with regular water changes

This has kinda been a recurring problem. Should I get a dosing pump to make things more stable?

 

[Randy Holmes-Farley Verified Community Expert]

It is certainly possible for the magnesium to be low. Testing error is also very common.

Magnesium depletes VERY slowly (1-2 ppm per day max, sometimes much less; not usually more than 10% of the calcium depletion rate) and should not need a dosing pump, but getting one is fine.

 

[saltyfilmfolks]

This has kinda been a recurring problem. Should I get a dosing pump to make things more stable?

Yes. Youll love it. But.

Mag as far as I have observed is the most common testing error.
I check then double check later.

If your not dosing and only doing water changes and your salt has a relatively good balance of alk cal and mag. Most do btw.
Cal alk and mag drop in general almost evenly.
This is why many seasoned reefers generally only test alk and then dose cal alk and mag proportionally evenly.

I would suggest looking at the dosing calculator Randy reccomendes and play with the ESV components. It will suggest the balances for each alk goal as well.

In the mean time just keep up on water changes and know that the levels are generally falling at an even rate even though the test may be slightly inconsistent.

 

[A Toadstool Leather]

It is certainly possible for the magnesium to be low. Testing error is also very common.

Magnesium depletes VERY slowly (1-2 ppm per day max, sometimes much less; not usually more than 10% of the calcium depletion rate) and should not need a dosing pump, but getting one is fine.

I might just retest then. I do water changes weekly so such a depeletion is odd