I have used vinegar and am currently trying citric acid. I find I need about 4 teaspoons of dry citric acid to lower the pH of 20gals from 8.3 - 6.3. Does that seem like a lot?

I do have hard water and which has a pH of 8.3 so I probably have some sort of a buffer in the water (well water). I use to use only RO water but I still had a high pH. What are some simple fixes to this problem?

Should I continue to add citric acid or vinegar in these high amounts? OR do I need something stronger like Phosphoric acid and where can I buy it?

TIA,
Chris

If you are getting good growth I wouldn't think it's hurting the plants. Given that your 4 teaspoons are for 20 gallons, that *seems* reasonable to me. When I tried vinegar before I used 3 teaspoons to take the PH from 8.5+ to 5.5.

For a while now I thought the PH was supposed to be at 5.5 but the more I read and the more I see my plants grow I think it should be kept around 6, so I'm trying that now.