With my 12 gal jbj nano cube i know i need to use some buffering agent to the top off water. the product my local "well equipped" store said to use is "seachem" 'reef builder" for a buffer. the problem i have is quanity to use. directions say "a half level teespoon per 40 gallons twice a week. well for sure i wont need anywhere that amout for topping off the tank between water changes. what would be the best way to add this and how much to use with my r.o. water system i use :?: live rock will be added shortly as im processing the water now and settling in for cycling.