I have a Hannah Checker for pH but for the last few months I have not been able to find the reagent. I like to buy it when I'm half way through the bottle, now I'm almost out and need something to temporarily replace it until it becomes available. My pH is one parameter I have to keep a close eye on because it gets super high. I do have one of those knock off pen pH checkers from Amazon, but I don't trust it at all. I was thinking of picking up a Salifert test kit. I use Salifert for my Calcium and Magnesium since Hannah doesn't have a good reputation with those tests. I don't have a lot at the moment to go to crazy on any of that special testing equipment. What do you guys use and trust?