Those will prob. work fine for you, just as the pool kit did I borrowed from my buddy with a pool to check mine, but if you're thinking of getting into growing serious, and anticipate checking on a regular basis (and guessing by the way you panicked from a "little" discoloration, LOL Honestly, I would have waited longer, maybe 'cause I'm lazy, or what, IDK
), I would recommend going to EBAY and looking into a good PH pen.
The problem with strips and drops, is that after you add nutes, the color changes, so then the drops are not accurate anymore.
I will say MOST nutes will make your PH drop, but I've never heard of one raising the PH.