they all have effect but pH may be the biggest effect. That ph is pretty high for a Kolsch. Temp and time seem good to me.PH was room temp. not sure what you mean by "corrected Ph". the past couple batches Ph was spot on in the 5.3-5.4 range. I keep my ph meter in storage solution, though I have not calibrated it for several months. Fermentation started this morning, what kind of reading should I expect during early fermentation?
Did you measure your ph at room temp? If so, corrected that would be a ph of 5.55 or so, which is just in ideal range, but for light beers like Kolsch I prefer a pH of 5.3, 5.2 for things like wits and weziens where I want a touch of tartness.