My PH was 6.0 yesterday AM in a 13,500 gal. AG with clear water and: FAC at 3.0, CYA at 30, and TA at 0. I've mixed 12# of Borax in water and added to the skimmer with the pump/filter running in the last 20 hours (3 additions of 4# each time). Before the last addition this AM, my PH was up to 6.4. How long do I need to wait after adding borax to accurately re-test for PH? Also, should I wait until I get the PH up to proper levels via this method to start in with baking soda on my low alkalinity? I thought I read somewhere to wait 24 hours after adding Borax to begin adding baking soda.