Magnesium through the roof

[SOGavity]

I don't know how dangerous high magnesium is to my livestock, but I have done some googling and now I'm worried. Using a salfert test, I emptied the syringe before the fluid turned grey. My Hanna checker blinks 1800. Ive tested this 4 times with the same result over the past 3 weeks. I use Red Sea Coral Pro salt (new to me as I used to use Instant Ocean but was having pH and Alk issues which is why I switched). My magnesium went from 1410 with Instant Ocean to 1800+ with coral pro. I do not dose anything at all. I'm finding my corals are not using any of the resources and are also not growing... it's been a year with instant ocean, about a month with Coral Pro. My salinity remains at 1.026 (35ppt) which I might lower since my corals are mostly LPS.

For the record, other than my corals not growing, they are healthy and very vibrant. I have a couple SPS corals (birdsnest and a hydnophora). The Hydnophora seems to be the only one growing.

I don't understand the high Magnesium. The bucket of Coral Pro says at 35ppt salinity, magnesium should only be 1410. Why is it so high?

Tested this morning
Salinity 1.026
pH 8.5
dKH 9
ammonia 0
nitrites 0
Nitrates 6.9
Calcium 390
Magnesium 1800+

 

[SOGavity]

P.S. Just made a fresh bucket of salt, it too reads very high magnesium.

 

[Miami Reef]

P.S. Just made a fresh bucket of salt, it too reads very high magnesium.

That means the kit is faulty, which is unfortunately the standard with almost ALL magnesium kits.

We don’t recommend testing it these days. Since the consumption of magnesium is extremely slow, most proper dosing systems will have a bit extra to offset consumption.

 

[SOGavity]

That means the kit is faulty, which is unfortunately the standard with almost ALL magnesium kits.

We don’t recommend testing it these days. Since the consumption of magnesium is extremely slow, most proper dosing systems will have a bit extra to offset consumption.

Really? Both testing kits are faulty? Does that mean my Instant salt was very low in magnesium?

 

[Uncle99]

I’ve used Red Sea Black for a decade and each bucket MG is 1340.

It would be hard to reach 1800ppm even with direct dose so somethings up with testing.

1800ppm would slow snails, maybe kill. Things might not be happy.

If everyone happy, I’d just leave that

 

[Dr. Reef Verified Sponsor]

I have kept reefs with 2100 ppm before with no ill effects. Some people including myself used to keep reef at 2100 to 2300 ppm to manage algae.
Might wanna get a different kit to compare to rule bad kits out of the way, just for mental satisfaction. Otherwise I don't think those levels will have a negative effect.

 

[exnisstech]

https://www.reef2reef.com/threads/just-say-no-to-magnesium-testing-rmm-is-born.1017528/

 

[gbroadbridge]

I don't know how dangerous high magnesium is to my livestock, but I have done some googling and now I'm worried. Using a salfert test, I emptied the syringe before the fluid turned grey. My Hanna checker blinks 1800. Ive tested this 4 times with the same result over the past 3 weeks. I use Red Sea Coral Pro salt (new to me as I used to use Instant Ocean but was having pH and Alk issues which is why I switched). My magnesium went from 1410 with Instant Ocean to 1800+ with coral pro. I do not dose anything at all. I'm finding my corals are not using any of the resources and are also not growing... it's been a year with instant ocean, about a month with Coral Pro. My salinity remains at 1.026 (35ppt) which I might lower since my corals are mostly LPS.

For the record, other than my corals not growing, they are healthy and very vibrant. I have a couple SPS corals (birdsnest and a hydnophora). The Hydnophora seems to be the only one growing.

I don't understand the high Magnesium. The bucket of Coral Pro says at 35ppt salinity, magnesium should only be 1410. Why is it so high?

Tested this morning
Salinity 1.026
pH 8.5
dKH 9
ammonia 0
nitrites 0
Nitrates 6.9
Calcium 390
Magnesium 1800+

The test is most likely incorrect as most of them are no good.

I wouldn't test Magnesium if you are doing regular water changes.

 

[ChrisfromBrick]

The test is most likely incorrect as most of them are no good.

I wouldn't test Magnesium if you are doing regular water changes.

salifert seems pretty good

 

[gbroadbridge]

salifert seems pretty good

You can use it, but it's not particularly acurate.

Mine reads 75ppm higher than ICP taken at the same time.

I wrote the correction on the box so now I just subtract 75 from the Salifert reading if I do a test.

 

[gbroadbridge]

A useful trick is take a measurement with all your test kits at the same time as you send a sample for an ICP. At the same time put aside a 500ml bottle of the same tank water and store it in a cool dark place with all your fish stuff.

Then, when you receive your ICP you know the values of all the major elements and you can use that sample as a calibration fluid for any new or replacement test kits.

I would not use it for as a reference for nitrate or phosphate :)

 

[ChrisfromBrick]

You can use it, but it's not particularly acurate.

Mine reads 75ppm higher than ICP taken at the same time.

I wrote the correction on the box so now I just subtract 75 from the Salifert reading if I do a test.

good to know. Probably can’t OD on mag unless you go way overboard