Yeah, it should work, just choke it down (1/8th inch hose will probably work). As Zandor suggested, look at maybe using some drip adapters from a local hydro store. It'd be nice to use a smaller pump, but as long as you put the injection point near the ph probe, it should keep you from over-dosing. This is because the concentration of acid will initially be very high near the ph probe, then making it shut off fairly quickly (this causes the short bursts I spoke about, and is also why a drip adapter would be a good thing).