@theppgcowboy sounds like a fellow all-grain brewer if you are talking about step-mashing! Good stuff
My reach in is 40 degrees, are the lactobacilli still being created a lot at that temp?
Retardation slows down everything...yeasts, lactobacilli, etc. However, while at a cold enough temperature the yeast goes mostly dormant, the lactobacilli are still able to grow.
I guess it is important to ask you what type of flavor profile are you looking for in your pizza dough? Are you looking for more of a noticeable, sharp sour note ("bite" or "tang") or for the mellower, some would say almost sweeter, notes which allow the wheat flavor of the crust to come forward more?
Wild yeast cultures can be tricky because you are not only dealing with trying to maintain a healthy balance between the wild yeasts (leavening portion) and the lactobacilli, but a culture is capable of producing both acetic acids (more sharp/sour in character) and lactic acids (more "mellow" in character).
There are a lot of tools to help get you to whatever flavor profile you are looking for:
1. Amount of levain/starter added to the formula
2. Maturity, or "age", of the starter when added to the formula
3. The hydration of the starter
4. Fermentation temperatures
5. Length of fermentation
I personally have found that both ambient (room) and cold fermentations can produce pleasing results.
That being said, I agree with Bill with regards to the 65į to 75į range. I typically use about 3.15% of Ischia starter and ferment between 68į and 72į for a total (bulk and proof) all-in time of 26 to 30 hours and I think the flavor of the Ischia really is in the pocket at that point.
As an aside, that length of fermentation at room temperature (26-30hrs) is not only a good range for me because of amount of levain added to the formula and temperatures, but because of the type of flour I use. The fermentation window between malted and unmalted flours can be very different --K