[DNA]

These are the measurements for 2013

Date.......pH..°C..Ca..Alk..Mg..Nitrat
05.01.13 8,08 27 400 7,7 1200
12.01.13 7,98 27 400 7
19.01.13 8,00 27 375 7,7
26.01.13 7,93 27 365 7,7
02.02.13 7,95 26 400 9*
10.02.13 7,95 26 400 7,7 1125 0
17.02.13 7,98 26 435 7,7 1200
23.02.13 8,03 26 390 9,6 1120
02.03.13 8,02 27 405 9,6 1200 0
09.03.13 7,97 26 400 9,3 1275
16.03.13 7,97 26 390 9,3 1275

On the 17.02.13 I switched to salifert Mg test kit and added Mg rocks in the Ca reactor.
A few months ago I manage to raise Ca levels by around 20 by replacing a Salifert test kit by another identical one.
The Ca levels before that used to be at around 380

My calcium reactor is a Deltec pf 601 and it is Suitable for Aquariums:.....
Heavy Stocking and High Illumination - 1350 lts - 300 imp. gallons - 356 US gallons*
Normal Stocking and Illumination - 2000 lts - 444 imp. gallons - 528 US gallons*
My tank is between light and normal stocking 320g.

This is the calcium reactors effluent.
Ca...Alk..pH...Flow
600 35 6,23 .7 ml/sek

I've got dry rocks in there so it's filled to the top with it.
The flow through it is already above what is recommended and so is the CO2.

My initial thoughts was that coraline algae forming on the dry rocks in the tank would suck huge amounts of Calcium from the water.
It's already been a year and I don't have much coraline.
My acroporas are doing good but birds nest and pocillioporas are not.

I did try to add 8g of kalkwasser over 3 days from 23.02.13 to raise pH and Ca, but pH stayed the same, Ca came out at 390 after and alk raised from 7,7 to 9,6.

So what do you recommend?