Why are my Mg and Ca so high?

[jrloyd]

Been testing weekly, tank has been running about 5 months. 40 gal IM fusion AIO tank weekly 10% water changes. I’ve been using Hannah testers that have worked well but the occasional test for magnesium consistently reads 1650-1800+. I ordered a Salifert test kit to compare and today my Hannah Mg showed 1680 and I couldn’t get a reading with the salifert which I assume means it was greater than 1500 according to the chart. I also tried the Salifert test for Calcium and I also could not get the reagent to change the color for getting a result, meaning I assume greater than 500. I use aqua forest reef salt mixed to 1.026 SG. Am I missing something or how can I lower the Mg and Ca? Should I be worried? Thanks in advance. Coral and livestock all seem well.

Tested a new batch of freshly made saltwater, Hannah reads 1650, the Salifert tests are still not readable. Pretty much same results. I looked up my batch number on my aqua forest salt mix and it shows Mg 1347 and Ca 421. I’m using RODI for my water source.

 

[KrisReef]

Let's test your tests.
Dilute 5 mls of tank water with 5 mls of RODI and retest with Hanna. MG reading should be 1/2 ppm of actual value. Those numbers seem very high (as you know) but Mg is difficult to read because it is present in such large quantities.

Otherwise, if your salinity measurement is off, you may be using too much salt and that would be a source?

 

[jrloyd]

Let's test your tests.
Dilute 5 mls of tank water with 5 mls of RODI and retest with Hanna. MG reading should be 1/2 ppm of actual value. Those numbers seem very high (as you know) but Mg is difficult to read because it is present in such large quantities.

Otherwise, if your salinity measurement is off, you may be using too much salt and that would be a source?

Thank you. Would the same hold true for calcium? I am going to recalibrate my salinity tester.

 

[KrisReef]

With everything trending high, it is a good possibility. Extra salt should lift all numbers higher. (At least until things start to precipitate out. )