"Effects on Alkalinity
Directions for use of the PhosBan Reactor state that alkalinity will drop when 5x the recommended amount of PhosBan is used. Under the conditions of this experiment, alkalinity dropped by about 19% when PhosBan was applied at about twice the recommended amount. At face value, this may seem negative until we consider that the presence of both phosphorus and silica lend to alkalinity (Standard Methods, 1998). Therefore, a portion of alkalinity drop could be attributable to their removal, and results generated by alkalinity testing in this situation could be partially attributed to removal of 'false' alkalinity and not a drop in carbonate content."
http://www.advancedaquarist.com/2011/6/review
The key study shows that the removal of phosphorus and silica, (a contributor to a "false" alkalinity) can cause a slight drop in your tank. I have a little more than 2X the recommended dose and I noticed that I add more supplements than I did in the past. This could also be do to my water quality in the Santa Cruz Mountains. Right now our water reservoir is under construction and maintenance; so we are getting our water from San Jose. This water is very hard and full of minerals. To combat this I am in the process of getting a water filter for the house, which will lower the PH but it will also pull out most of the excess minerals out of the water; some of which are silica. So my problem might be unique based on my base water quality.
