The dosage is 6g (1 level teaspoon of Reef Builder) per 300 liters (80 gallons) to increase alkalinity by 0.25 meq/l. You should not raise your alkalinity more than 1.0 meq/l at one time. Your total water volume must be less than 44 gallon but let's say you have 40 gallon. You need 1/2 tsp of Reef Builder to raise alkalinity by 0.25 meq/l. You can add 2 tsp to raise alk by 1.0 meq/l, but no more.
Before you add anything more, please measure your alkalinity. Do not follow the instruction on the bottle blindly since it's written in a very general terms. Reef Builder will raise your alkalinity without raising your pH very much. In other word, Reef Builder is very much like Reef Buffer. I really don't know the difference between the two. When you raise your alk too high, you will precipitate calcium out of the water and at the same time shoots down your alk down to 6 dkh or below.
When you run out of Reef Builder and Reef Buffer, I recommend that you switch to Baking soda for alkalinity supplementation or start using kalkwasser (pickling lime.) They raise alkalinity just as well as commercial alk supplements, but they are a lot cheaper.
I cannot stress enough about measuring alkalinity regularly and keeping it in 8 to 11 dkh range.
Tomoko