Pre-mixed x2 2L bottles with nutes (each 2L ~5.7 pH) and dumped the 4L to res. pH went to 6.3 ....... ok... lowered to 5.7 10 min later 6.5 now. res was just cleaned. the x2 air stones inside? old durt in the tubes? there should be no runback of old water to the res from the x4 autopots, as res is 1m higher. the pH pen seems to be Ok. ideas? coz im out.
If I'm honest I have never checked PH sooner than 24 hours. Mine often swings up to about 6 within 24 hours but for all I know this may happen in the first 10 minutes. Does this always happen to you?
first time i didn't get what happen so i lower pH back, and it kept going up, then i removed the res, kept manual feed. second time it reoccured, so i washed my airstones and res with low pH solution overnight, same result. Here i perma removed the res and already in week 2 of flower. i dunno if its the conditions here in my part of the world (mid east temps+ humidity+low air movement) or might even been pH pen issue. my up swing is far more severe & faster it seems, this grow will be without a res til the end. i just didnt like the idea of my girls getting 5.6 then after 20min its 6.5, or would it stabalize after ~24h and i worry too much?