dig that. Can you just grab some of the test strips from WalSatan? They're not exact, but they'll let you know you're in proper range at least when you water.
I don't know your grow medium or feed, but I'll be honest, I never check ph either, and it's for only one reason. Every time I feed, I add 1/8th tsp/per gallon of Miracle Gro Bustin Blooms 15-30-15, or the WalSatan version called Garden Sense that is $3 cheaper, but a box of either is still less than $8. It adds a little bit of feed at that dose, but not much, just reduce your regular grow by a ml or so to compensate. The chelated salts keeps the soil ph in proper range.
Of course, if you're dead set on organics, or something of that nature, then this method isn't for you, but it's worked for me for decades, with multiple water sources in multiple spaces. Just make sure it's the 15-30-15 and not the All Purpose with is 28 for its N.