What is the best way to adjust pH? My tap water is about 8.5. I have an RO unit for my Reef Tank top off water but its pH is about 9.5 to 10. I adjust it for my reef tank but the buffer I use only brings it down to 8.3. I have a digital pH/TDS meter now so adjusting is not a problem. I just got the meter this past weekend. I was shocked to see that my water pH was so high and I have not been adjusting. I used some Acidifier with Iron and trace elements that I got from my local garden store to adjust the water. It's a once a year additive( directions are for acid loving plants and said to mix one bottle to 15 gallons and apply to soil at base of plant and will work all season) so I'm afraid to use it to much, but I will have to adjust for every watering and I don't want to get to much build up of trace elements found in this solution. I did a flush with water that I adjusted to 6.4. The water effluent from the pots when flushed with the 6.4 water was about pH of 7.8 so I know it was much higher. I flushed and measured the effluent until the effluent from the pots was pH of 6.8. Hope I did not shock the pore little girls. BIG QUESTION? What's the best fluid to use for pH adjustment? Thanks!!