How often do you check the pH of your nutrient solution? I am using coco with autopots with a 12 gallon reservoir. I have had some pH issues during this grow (too high). I mixed the last batch on Sunday with a measured pH of 6.0 and 6 days later it measured 6.38. I am surprised that I have to adjust that much. Is this your experience as well?
Yes the ph always drifts up with time, perfectly normal.
I wonder if it for the same reason my tap water drifts up about a point from 7.5 to 8.5 when I leave it outside for a day or two
I believe its the oxygen in the water that raises the ph but could be wrong.
As CO2 off-gasses, the ph goes up. Any aeration/movement of the water/nute mix helps CO2 to escape, raising ph even faster.
Good info. Thanks. How often do you check yours?
I don’t really check much as I know the pattern. I water daily (coco) and mix 4 days of nutes at a time, it’ll start at 5.8, then will 6.0 a couple days later and 6.1 on the 4th day, not enough for me to bother adjusting the ph, though I would if it got over 6.2.
I check my reservoir once a day, but I don’t adjust it until it’s “way off” aka if I start at 5.8, I’ll PH down once it’s over 6.5 or PH up when it’s under 5.2. I mostly just chose some random numbers but it has to do with which end of the spectrum you hit before the plant can’t make use of any nutrients. I.e. too High or too low and lockout happens but anywhere in the spectrum is fine.
Same experience. Temperature was also an issue even though it was not in the tent. Room temp. would reach upper 70’s. I was also only feeding one plant. I dealt with both pH and temp rise by mixing 5 gallons. Put two or three in the res and the rest in gallon jugs in the refrigerator. I would top off the res with a gallon the next couple of days. Then every 10 days or so I would dump the res and rinse it out. I use Jacks so no big loss on the nutes.
Thanks all. I have always been a bit slack with my pH. Now that I think my plants had an iron deficiency from high pH, I have changed my tune. Thanks for your help.