Low alk, how to adjust?

[Grenade Glass]

Hello, I started noting some tissue receding on a fungia, and all of my branching euphyllia hasnt been opening up much. So I decided to check my water params.

My current water params:

Salinity=1.023
Ca=400
DKH=5.4
Meq/L=1.94
PH=8.0
Nitrite=0
Nitrate=10-15
Ammonia=0


I have a 120 gal system (90 display, 30 sump) which has been setup since August 2010. I do a 40 Gal water change about every 2 weeks, but it seems that I will need to start dosing ALK and CAL. I just ordered the B-Ionic 2 part (64oz). My question is how should I go about adjusting? I assume start with the ALK since that is the lowest reading. I have no prior experience dosing 2 part solution, so please excuse my total lack of knowledge!

[bertoni]

FWIW, I would raise the SG up to 1.0264 or so over a few weeks.

This calculator will give you an idea of how much to dose:

http://reef.diesyst.com/chemcalc/chemcalc.html

I'd use baking soda for large changes. Assuming 80g of actual water in the system, I get about 4 tsp. I'd probably dose half that, then measure in 5-10 minutes.