Runoff ph, flush

If you have flushed, it's done it's job and flushing more only hurts. Got some whacky pH issues... most likely due to the flora in your substrate or weird chemistry due to mutliple brands of things being pumped into the substrate. You can also cause a Ca/Mg def with k/p-toxicities - either one. So, becareful about assuming things. If you use ill-prepared coco, it's likely the coco's fault from leeching Ca/Mg from your fertilizations and realeasing a bunch of K+. Someting is increasing pH in your soil. There are things you can use beside just pH water to lower it. In future, you can amend with something like Garden Lime an dthat will help maintain a pH closer to 7 as well as provide additional Ca. It's less useful for you or after a grow begins.. takes months to be useful by plant. Fertilize normally, because you jsut strippe dmost nutrients from substrate. May sure it's a healthy concentration and not instructions from some label with a cartoon graphic on it. Don't add a bunch of supplements, and if they are needed, one more reason to find a different brand instead of letting that one suck your money down for nothing but pain and problems. The fertilized water should be acidic enough on its own. definitely check, if you haven't. Giving slightly lower pH water is probably a good idea too, but i wouldn't over do it... You don't want massively different pH solutions going into substrate and causing wild swings in a short period of time. Ease up on how often you are feeding for a bit. i'd wager you just have a bloom of micriboes causing issues in the soil. (if soilless could be other reasons like i said about ill-prepared coco nearly killing plants, lol)

runoff ph is only important when there is a serious problem,to give an idea. try to adjust irrigation water ph to somewhere between 6.2 and 7 ,this is more important. they'll be able to absorb when soil is wet enough if ph is in correct range. 7.8 sounds still way too alkali, but if there isn't anything slowing down its growth,I wouldn't touch soil ph.It will already drop in time as you keep feeding