stuck sparge: blow back solution

Hi all. I made a "fancy" new manifold out of 1/2-in CPVC pipe to replace my SS braid in the hopes of using fly sparging to increase my efficiency from a meager 67%. I'm trying it out today for the first time on a wheat beer, and got my first stuck sparge. Not 2 sec after I opened the valve to vorlauf, it stopped dead. Because of problems getting the temps right in my step mash, I had less than 1-gal of free space in my 10-gal cooler, my mash was super thin so I didn't see any use in adding more liquor. I stirred a few times but no help. So I blew hard into the outflow hose to clear the manifold, and the 2nd time I did it, the sparge flowed again.

The manifold is rectangular, with 4 pipes running along the long-axis of the cooler, and has slits that I cut with a dremmel wheel every 1/4 to 1/3 in, facing down of course. There is only about 1 pint of dead space with this setup.

So just how bad was it that I did this, and, is this common on a wheat beer even if I use rice hulls? The manifold is basically touching the bottom of the cooler, and I'm wondering if I should lift it up by a fraction of an inch?

-ben

I've had the same issue with wheat beers on a similar setup. I usually add extra rice hulls to the mash and sparge slower than usual. Extra time spent with the vorlauf will also help. If all else fails, squeezing the hose a few times usually knocks it loose.