pH irrigation / runoff

need a header in that excel snapshot of whats what. I agree with a lot of the advice below.

Runoff will have some excess solutes in it compared to what you add. So, it's pH and EC are not entirely representative of what sorrounds the roots - which is what matters the most. pH drift is a sign of an inferior product when speaking of soilless or hydro fertilizers. Soil fertilizer is less controlled in this way and the expectation is the soil and it's biome will keep the pH in check. Before you get all OCD about runoff metrics... is the plant healthy? Is it growing well? If yes, then i wouldn't worry too much about it. continue to pH adjust what you add to 6.5-6.8 for soil and go on your merry way. Be more concerend about a continuing trend... a regular offset is fine, but if it contineus to rise or the pH continues to drift even further, then you can start worrying and do something above and beyond at that point. Keep track of how long it takes before that occurs and you can pre-empt it with a little extra runoff at incremental points to dilute it. If it continually climbs, adjust concentration of fertilizer down a little bit too... should be able to avoid any need to 'flush' or dilute substrate with proper fertigation methods. it's all about maintaining a consistent equilibrium... not rising, not falling...

A lot like when rainwater flows down a valley it often picks us up and dissolves some minerals which raises the ph.

Hello- The ph of the irrigation water is more important. Your runoff ph is higher as some of the soil contents are being flushed out. Your numbers look totally normal to me.