probably referring to mash pH around 5.2-5.4 and as for water, water that has low permanent hardness.
that and an appropriate amount of calcium to encourage those pesky yeasties to drop out when they are done with their meal.
Maybe that is my problem with Hefes. I can never keep them cloudy longer than a couple of weeks.
don't feel too bad, big big pro hefe breweries spend mega bucks on trying to get a hefe to stay cloudy longer.
+1. I've always let a slight bit of hefe yeast into the keg (racked carefully to get the top yeast layer and not trub). When the beer starts pouring a little clearer than I want, I gently rock the keg with the CO2 valve closed (not looking for extra carbonation). It's a temporary fix, but it works.
EDIT - The one trick is to remember to gently rock the keg before the first pint if it's been a few days since the last one, or else you're pumping out most of the yeast in the first pour.