Runoff ph at 8.3 HELP!!

I am on day 35 of flower. I was holding a consistent 6.8pH ronoff until I used molasses then the next watering my runoff turned to 7.5.

I just flushed yesterday 21 gallons of 5.9pH'd water in a 3 gallon pot. Finally got the runoff down to 6.8.
Water never came out clear even after 21 gallons.

This morning I check the residual runoff and it is at 8.3.

I am growing in soil.
Watering every second or third day depending on dryness.

Little leaves on buds are starting to turn brown.
Lower leaves are turning lime green and yellow.

How do I get the pH to stay down?

I think the best way is to pre-buffer your soil and you wont have to PH your water im not 100 on this havn't done soil in a few years

the only benifical thing a plant takes from molasees is rhizoshpere. which it struggles to breakdown also youre plants produce rhizoshpere themselves. so in a nut shell its a waste of time.
also Reading youre ph is a bad thing to do. it will only cause you trouble and head ahce and have u adjusting thing and changing things when there is no need as ph reading can differ every reading you take this is down to the plant taking different nutrients at different level at different times ect. ph swings also are natural. can even be caused by roots sweating. then you try to adjust by flushing which in a lot of case can make the problem worst.

if you keep youre ph at the same level through out you're grow and not add unnecessary stuff(or only adjust slightly to help with defficencies). you should not have to be worried about it. i never do. just read youre plants there tell you if you have ph issues

aluminum sulfate- 1tsp/gallon of soil or soiless mix to lower ph. powdered lime to raise ph