Same as my receipe above for raising except you use liw ph flush.
Yours is high, example 7.2 or so and want target of 6.5 to 6.8 in a 3hal pot. Multiply your gpot size by 3 and that how many gallons to use to flush.
If 7.2 for ex, iwould ph flush water at 6ph and start flooding plant allowing all runoff to drain. Check ph levels 3rd way thru to see if any changes and how much. If half way ther keep going as until readings are satisfactory.
If not, drop ph of flush water lower and proceed to flush, check ph runoff halfway thru to see any changes.
Best time imo is morning so plant cann absorb wster, if outdoor sun and wind help evaporate flush. If indoor pkenty of air flo and if possible some small fans low speed on the pots not the leqves or plant itself, avoid windburn.
Once ph in soil is stable you shoild check runoff once a week. And water or feed in at ph adjusted levels to compensate off ph levels.
I bought a expensive ph meter cause ibwas tired of replacinf cheap ones at $15 a pop. I got one at 60bucks and trust it as i compared to the box of old meters. It read along the two i trusted of 8 meters.
Invest in a good ph meter is king!