How do you test your Ph?

I had 1 drop left of General hydroponics ph test that turns gold at 6.5 but isn't accurate you could be 6.2-6.7 and hardly tell the difference.
So I checked on one I fed yesterday and she loved the tiger bloom but I fucked up giving a few drops of acid when the final 'test drop' tested at 7.0 it didn't drip out so I dumped the sample into the practically empty contaminated bottle and now she has a bad case of mag def :/

I wonder if I should wait ~4 days for her to dry out or to immediately flush 6.5 ph'd pure water or brita filtered 6.7 ph without ph drops

Any recommendations on affordable ~20$ digital ph meters? Fuck the little bottle from GHydro and I hate ph sticks. The reviews for some at Walmart made me post this add, Happy toking!

If you're not going to pay for a good one don't waste your money. Blulab for me all day everyday.