So now what?

[AshevilleReefer]

So I started testing CA and KH. My first readings were Ca 840ppm KH 6. Now after some dosing and a water change the readings are Ca 640 KH 8d. I know the Ca should be up there but what should I be looking for with the KH? The higher it gets the lower the calcium drops? The LFS guy said to keep the KH up at 14. This seems high to me and contray to what I've read. Do I need to be testing for mag as well? How essential is it? Right now I'm testing for PO, KH,CA and ammonia, nitrite and nitrate.
90 gal
20 gal sump
Matrix
Current skimmer
3 powerheads
400 MH 14k
Tang and 3 chromis

 

[Anonymous]

Ca should be between 400-500 and dKH should be anywhere from a 7-12. I keep mine at a 9-10.

 

[AshevilleReefer]

What is the benefit of keeping it higher?

 

[Anonymous]

Natural seawater on the reef is between 7-10 dKH. I keep mine on the high end because the biological process will drive down Alk, as will too much Ca. Plus a higher dKH, IME helps keep algae at bay. It will also help keep pH values in the proper range.