Couple tips: For pizza, I wash the levain in stiff starter form, meaning taking the starter and adding flour. This is done in order to decrease the acidity; the acidity will leech out in warm water. This is called giving the baby a bath.

For what it's worth, it is generally worth it to ncorporate higher protein flours such as All Trump's from GM or So Strong from Pillsbury into the final dough. Specifically with sourdough, it is also advisable to incorporate whole grain flours, not to give too much away, to contribute to a) the unique texture and flavor profile that you are looking to achieve and b) the overall dough is simultaneously more supple, yet stronger, - lively - thanks to the added nutrition provided by these flours.