I set up a 75g planted tank about 3 weeks ago. I have 10 celestial pearl danios and some rams horn snails. My tap water has a ph of 8.2 kh and gh are both 7. I’ve done a couple 10% water changes with ro water and my ph is still at 8 and kh and gh are 6. Am 0 nitrite 0 nitrate less than 5. Any suggestions on how to lower my ph.