I haven't kept fish for a few years now. I'm having an issue with my PH being too high. My KH and GH are good, but my PH is off the chart! I did a water change yesterday and I did one today too cause my KH went up too. I think cause I used a bunch of that PH down stuff. Well, PH down did NOT work for me..I put like 30 drops in over many hours and my PH is the same. This change I used RO water My filter isn't that old. I saw the review on this tank by co-op and will be changing out my filter to more substrate. I have 4 guppies, two shrimp and a snail in my planted 5 gallon aquarium. I'm starting to think the PH tester is wrong. Oh, and I don't like the tester strips. They are way different than what the kit says. P.S. I tried to get the picture to sit up straight... No bueno!