Yes, if you think the soil is full of nutrients then a flush might be in order. I'm betting you're going to have to order your test supplies online, but see, here's the thing that gets me. How the hell did we grow ANYTHING before we worried about things like the pH?
I have the exact opposite problem, soil that tends towards the high end of pH, and water (deep well) that's even higher. I'm sure that we get it close to 8, if not above, straight out of the tap. Full of minerals.
Baking powder is NOT the same thing as baking soda, don't get them confused, or your plants will bubble and stuff the moment any moisture hits that stuff. A big reason for the presence of baking soda in certain baking recipes is specifically to lower the pH (baking is chemistry, that's all I know, and that's my story and I'm sticking to it).
If the pH of your water is a bit higher I'm betting that would help, too.
Oh yeah, edited to add the one major lesson I've learned in life, when trying to keep living things living--if it ain't broke DON'T (try to) fix it! If the plants are growing fine in that low pH soil, let 'em be until or unless they "tell" you they're not happy there.