PH and Fertilzers

I have been using a fertilizer (FloraPride) with every water change and I noticed my PH seems to rise after the water change. Could the cause of this be the fertilizer? My tap water PH is lower than the PH reading I'm getting from the tank so it can't be the water I'm adding.
Also will the use of sodium biphosphate to lower my PH cause an increase in the algae growth?