PH can change due to many issues. If the tank is just recirculating and you're taking water from the res and hand watering then the PH increase is likely due to evaporation, temperature fluctuations or bacterial growth.wutang wrote: ↑Thu Aug 17, 2023 9:09 pmI just thought of your comment about two hours ago as I was washing up lolHmr81 wrote: ↑Thu Aug 17, 2023 11:32 amthats interesting. i know we arent using the same nutes but with the veg mix of a and b i found my PH drifted a lot(im talking .5 per day), but with the air stone and pump it didnt drift as much, perhaps .4 over about a 5 day period. i would PH down to 5.8 and then repeat. but with the flower nutes a and b if ound i got much less ph swing but then again, i have never used the flower nutes without the air stone and pump.
So I thought added an air stone or circulator increases the pH.. but your theory means it keeps it more stable...interesting...maybe I read wrong or for some it does and some it doesn't or reduces the swing
The reason why circulation pumps can slow down the PH rise is that moving the water will cause the water to pick up co2 from the air and form carbonic acid
CO2 + H2O -> H2CO3. The higher the PPM in the air the more aggressive the effect. In my personal experience, evaporation will outpace the changes due to recirculation but it deffo slows things down and the PH either stabilises or climbs much slower.