I am unable to explain run off pH increase

[Amatfumusviriditas]

I thought they looked like 3's, but I went with what you typed.

Wording was misleading , 1 gallon was referencing back-ups in tent that were not pictured. You had it right.

 

[Aqua Man]

I seem to be having some form of strong buffering effect coming from grow media as pH of solution input is drastically climbing.
Today, pH in around 6.1 (usually around 6.3, but I decreased trying to diagnose issues I’ve posted earlier). Immediate reading of output pH already 7-7.1 and after sitting a couple hours had increased to 7.8-7.9.ive never experienced this effect before. Tested soil pH with basic probe it indicated around 6.5. Unused input solution stable at initial reading.
Nothing has changed significantly in my grow, same water source(glacier dispenser), same nutrients (jacks 321 w/ recharge and tribus) only different Si and fulvic. Same brand soil ( FF happy frog with added EWC and perlite 10:2:2). I’ve been struggling this run and having a hard time figuring out why. Initially thought light stress and/or Mg def (based on info in other threads) but now with this pH thing I’m stumped. Temps and humidity more dialed in than ever. Based on previous limited experience it seems things should be rocking not struggling. I’m using a new light (HLG 350R) that initially I figured was too much but I’ve been checking PPFD with photone app and keeping it dialed back (around 200 PPFD) There are some pics in initial thread.

Veteran noob, I’m my own worst enemy, lol.

Greetings everyone, guess this is a bit of a late introduction and a request for assistance. I’ve been growing (struggling to) off and on since 2013, with marginal but improving results, still far from what I hope for. In my early 50’s now, growing was always an unfulfilled burning desire, and...

www.thcfarmer.com

Not sure where to go from here or what best intervention to be. Mixed genetics about 24 days from breaking soil.
I’m seeing a little stabilization if not improvement with after foliar of light mgso4 and an initial couple flush/feed to stabilize runoff as early intervention due to runoff with elevated ppm/ec. This is now closer to normal but pH has never ramped up like this.

It's because of respiration of plants and microbes. They both intake o2 and release co2. Density of the soil, water saturation and gas exchange play a big rolenin this.

Co2 dissolves and forms carbonic acid lowering ph. So runoff is lower ph. After hrs of air exposure the water releases the carbonic acid in the for of co2 as it tries to reach equilibrium with its surrounding air and ph rises.

Wanna see a prefect example take you tap water fresh from the tap. The water is in a closed system so any co2 formed will dissolvein water and form carbonic acid. Measure ph and let it sit for 12-24hr and check it again. It will be higher and typically 0.4 increase.

This can be sped up with aeration and is commonly seen when a res or system is filled directly with tap water. After an hr or 2 you want to re PH .

 

[Aqua Man]

So go by the initial reading not the reading after it sits for hrs.