Why is my Mg so high?

[SallyWho]

According to my Salifert test kit, my tank's Mg is sitting at >1500- their chart only goes up to 1500, and I emptied the syringe before I got a color change. I tested my mixed saltwater and it was 1440. I use Instant Ocean Reef Crystals, and did a 15g water change yesterday on my 120g tank with 40b sump (approximate total volume around 150g). I repeated the test to be sure, but got the same result. Why would my tank's Mg be elevated out of reference range when the salt mix wasn't testing that high? If there was something wrong with the test reagents, wouldn't both the tank water and the barrel water test out of range? Assuming the result is correct, will a Mg level that high harm my corals? I don't have many and they're not fancy- zoas, trumpet, duncan, monti cap, hammer, digi- but I don't want to burn them. Thoughts? Thanks for your input!

 

[stanleo]

My mag runs high with the same salt mix. After a water change its 1540 and over two weeks gets down to 1440. To get a more accurate reading on the fresh salt mix from that salt I mixed a sample of 50% RO water and 50% fresh salt mix and multiplied the result by two. I discovered that my salt mixes to 1600 which is high. Corals seem to do pretty well in my system.

 

[Randy Holmes-Farley Verified Community Expert]

If you do not reach the endpoint, start a second syringe to get the actual value By adding the two together. It likely is not a problem, so don’t panic.

 

[Geebs19]

Like Randy mentioned above. That’s what I do and I use blue fritz. Usually runs about 1580-1600

 

[SallyWho]

Thanks for your help, guys/gals!

 

[Backreefing]

People who design the salt mixes think you probably need it so they put a lot in . They’re correct most of the time . Example a guy does 10% once a month as his routine. He probably would need it .