Ca over between 500 and 600

[heitlager]

I'm trying to figure out what could cause Ca reading to go off the scale. Tested with one testkit and got over 600. Bought and tested it with Salifert Ca and got on regular test 520 but using the diluted test 660.

KH is 11.8 dkh or 4.23 meq/l
pH between 8.20 and 8.50
Temp 81

NO3 = 25 ppm
PO4 = .5 ppm

All test kits are Salifert.

Have a refugium filled with Caulerpa. Used to be on 24/7. Using a Nielsen Reactor to dose Kalkwasser with topoff 24/7.

Used to dose kalkwasser into refugium, but then I noticed a Calcium Carbonate precipitate forming on the leaves of Macros. Moved the dripper to sump over small powerhead that agitates water. Yesterday changed Refugium to reverse daylight.

BTW I know the NO3 and PO4 values are high. Working on lowering it.

Any thoughts?
Thanks

 

[Len]

I'm no chemist, but those figures don't add up, and I suspect possibliy some kind of interference with the Ca test kit, though salifert says no such interference exists (at least not magensium and strontium). But again, this is just speculation from a "chemically-challenged" mind