Earth juice natural down "not stable"???

I just bought a different ph down its the earth juice natural down and for some reason it is not stable. I have always used the general hydro ph down but figured I'd give this natural citric acid crap a try and I can't keep my ph stable in my cloNing machine. I'll get it down to 6.4 and after a hour or so it goes it up to 7.4 has anyone else had this problem with earth juice.

I've been using it for years. It swings up for me when I use pro tect. Usually takes a couple hours after I mix nutes to stabilize