Please help with runoff PH

Hi, im 2 weeks into flowering. Im using the full line of foxfarm nutes. my runoff PH is at about 4.5.

Im using 3 gallon pots, and today i flushed them with about 5 gallons of very high PH water, like with a PH of 10. and after flushing my runoff PH was still at about 4.5

how can i make the PH go back up without transplanting them?

My friend just had this same problem about a month back and he flushed with water adjusted to 6.5PH. He then watered with his normal nutes and adjusted the PH to a constant 6.5. Now, all is well and the soil is between 6.5-7. (Be sure to adjust PH AFTER adding nutes.)