So I tested the tap water I've been giving them. The pH is between 7 and 8! I'm glad I found this out now before I started giving them nutrients. Before tomorrows watering I'm going to adjust to 6.3. I noticed a bit of yellowing on Watson's leaves... it's hard to see in the pictures. I wonder if it's because he's thirsty, full, or needs a pH adjustment.

Oh and I also added a drop of acid to see if it would change the color. BAM! Immediate drop to ~4.0. The water turned bright red. At least I know the stuff works.