Review on Seachem Discus Buffer 250g: Optimal pH Solution for Vibrant Discus Aquatic Environment by Tat Lousteau

My aquarium is 4 years old. I keep a fish in it. betta My water test says no problem. It contains few living plants. I have an entire house water filtration system. RO and DM water. However, my PH is slightly higher than I would like. 7.8 so I wanted to lower it to at least 7.0 or even better 6.8 since the ideal pH for bettas is on the lower end. I never had an algae problem until I added this discus buffer which I can see contains phosphate which I've read causes algae. I don't use CO2 injection. I followed the directions and dosed the indicated amount each day and got it up to 7.4 before I started seeing algae growing like crazy on plants, glass and decorations. I always did a 20 percent water change once a week. I've never had problems like this with algae. I recently added two cutappa sheets to this 20 gallon tank but I don't think that's the reason. I have a feeling it's a buffer. Bad because I wanted to lower the PH, but I want one that doesn't contain any algae-causing ingredients. So I went back to the drawing board and searched for a PH buffer that would give me what I need without causing other problems.