Question about test kits

[waterbear]

OTO and Phenol red in these cheapie kits are pretty interchangable. I don't think you will see much, if any, difference in using 4 drops vs. 5! The difference might be in the amount of water the sample tube holds. Have you checked to see if they hold the same amount of water?

[dirtysouth]

Thanks David. I'll surely purchase the kit.

Waterbear, I can't tell a difference in sizes in the tubes. They look about the same.