I was told and subscribe to the proper way to flush, run pH7 water through the soil till the pH of the runoff rises back up to pH7 or close enough, anyone else saying different knows somthing i dont and would welcome the extra knowledge or is wrong.
I use to believe all the pH nonesense and reading runoff till was told otherwise and believe me i didnt want to believe i was wrong at first. Lime is the only thing that will pH your soil, your runoff is telling you the fert level normally, it should rise and fall as the plant eats the nutrients and you replace them, try checking the ppm of your water.
A proper flush cleans the soil and hence water in reads similar pH to water out, no good flushing with pH8 water till you get pH7 runoff, this is wrong.
I doubt you will get half as much pH problems if you just ignore it!lol! Add dolomite lime if you do have pH problems and is an easy way to solve it. Do you read soil pH in the runoff? this is generally wrong unfortunatly. Peace