I see that the Ph up has a TON of Potassium in it. That could throw things off. I also see this is recommended for hydroponic use, I'm guessing because of the "enhanced crystals" inside. I looked for the website but couldn't find it. I do see it being sold from a bunch of generic gardening sources like Walmart, Home Depot, amazon and even eBay.
I would have to put this on my list to pass on if another option is available. Preferably the GH Ph up & down.