I use an auto mixer with a small magnet spinning at the bottom of the vile. I also redid the test today and come up once with 1360Normally You have a span of +- 30 ppm with Salifert Magnesium test.
Take a look at Your values.
The first two is 1350 and 1440 Lets say they both should have been 1395.
Then we have 1410 3 times followed by 1360 and 1420. I value these 2 as 1390.
The last 2 is 1370 and 1440. Name these as 1405. I think You have a stable value around 1400.
The problems with Salifert Ca and Mg tests is that they use very small volumes. That means that you have to be extremely careful with the 2ml volume test water. The 1 ml is easier because that syringe is longer so You get a better precision with it. And it is better to be real slow at the endpoint.
I recommend that You take 2 tests the next time. And if they are different take a third. When You are in +-30 for Magnesium it is OK but when You get extremely skilled +- 10 can be possible.
More about the volumes:
In the end of the 2 ml syringe You can make about 20 drops per ml so the 2 ml is about 40 drops.
Half a drop left or not left at thew end of the syringe means 1/80 of the test value. That is near 20 in the magnesium value. A drop left on the the sides of the long 1 ml tip can make 70 mg less value.
It is extremely import to take the sample and test fluid in exactly the same way every time if You want consistent values.
I find it very good that You save Your values. That will make it easier to handle Your reef.
It took some years before i began to log but now I will never quit it.
So strange though, since I don't do any water changes directly from the tank water the Mg value should be slowly depleting,Normally You have a span of +- 30 ppm with Salifert Magnesium test.
Take a look at Your values.
The first two is 1350 and 1440 Lets say they both should have been 1395.
Then we have 1410 3 times followed by 1360 and 1420. I value these 2 as 1390.
The last 2 is 1370 and 1440. Name these as 1405. I think You have a stable value around 1400.
The problems with Salifert Ca and Mg tests is that they use very small volumes. That means that you have to be extremely careful with the 2ml volume test water. The 1 ml is easier because that syringe is longer so You get a better precision with it. And it is better to be real slow at the endpoint.
I recommend that You take 2 tests the next time. And if they are different take a third. When You are in +-30 for Magnesium it is OK but when You get extremely skilled +- 10 can be possible.
More about the volumes:
In the end of the 2 ml syringe You can make about 20 drops per ml so the 2 ml is about 40 drops.
Half a drop left or not left at thew end of the syringe means 1/80 of the test value. That is near 20 in the magnesium value. A drop left on the the sides of the long 1 ml tip can make 70 mg less value.
It is extremely import to take the sample and test fluid in exactly the same way every time if You want consistent values.
I find it very good that You save Your values. That will make it easier to handle Your reef.
It took some years before i began to log but now I will never quit it.
The water level never changes, I have a 4L ATO on top of the tank and always refill it before it's completely empty. I also use a salinity refractometer to check every week always at 1.025.How do you know salinity stays the same? I expect test error is likely, but salinity does not stay exactly the same unless the water level is exactly the same. How closely are you controlling the water level?