I realize this is an older thread, but something that MAY of contributed to your lowering PH, was the introduction of your Phosban. The information that Mike gave me about it when I won some at the November meeting, was there is an initial drop in PH that you need to be careful with, so your tankmates don't get stressed.
Thank you for this thread by the way. I've known that I need to start using some form of baking sumptin to help my Oceanic, and this had the EXACT information that I needed! (6:1 bakingsoda/washing soda... baking at 250 for 1 hour... 1 tps per 20 gal)
Thanky Thanky Thanky!