I have a question about

[Tofer]

Is it normal for my calcium and magnesium to drop and Alk stay level I do have 2 Duncan's and 1 hammer and coralline actively growing?
I was thinking there would be some sign of a drop if the others are being used as well.
Could weekly water changes be holding it steady and the others are being used quicker ?

 

[Randy Holmes-Farley Verified Community Expert]

No, calcium and magnesium cannot drop without alkalinity declining a lot, unless you are dosing alkalinity, or it happened due to a water change.

Otherwise, it is testing error.

The ratio is roughly 18-20 ppm calcium and 0.5-2 ppm magnesium for each 2.8 dKH of alkalinity consumed.

 

[Fishhands]

I have this same issue. I dont test mag much, but alk will stay @ 9.1 with red sea kit, and i dose 10ml brs ca per day. 5+ ppm in my 24 cube about 19 g actual water. If alk is consumed then its @ .7dkh per day i should be dosing?

 

[Randy Holmes-Farley Verified Community Expert]

I recommend dosing of two parts based on the alk demand, not the calcium, since the alk always changes much faster on a percentage basis when it is calcification providing the demand.

If you have no alk demand for some reason, it is OK to keep dosing calcium to maintain it if, say, the salt mix is low, etc..

 

[Randy Holmes-Farley Verified Community Expert]

This has more:

When Do Calcium and Alkalinity Demand Not Exactly Balance? by Randy Holmes-Farley - Reefkeeping.com

http://reefkeeping.com/issues/2004-12/rhf/index.htm

 

[Tofer]

Thank you will have to retest the Alk a little while when I get home .