Even though it is a bit more work, I vorlauf until the wort is clear, ( which is something I have read to do) and all the small stuff is now locked into the grain bed. Okay, there is a a tiny bit of particulate, but is basically clear.
I have no idea how long it takes me, as I recirculate it by hand. At that point, I slowly drain my tun into my BK. I had never checked the temperature of the wort after the sparge has started, until the other day and surprise!,180 * F water was now 146* F after the cooled off grain was once again covered in water. Doesn't sound much like sparging temperature does it? So, I changed my method. I know by experience I am going to need about 7 gallons in the BK to start, so I pour 3 gallons of boiling water onto my grain bed, give a small stir, cover and wait ten minutes before I slowly drain my grain bed at the same rate it is being refilled. I have found a 2" head of water helps to prevent stuck sparges. This step usually takes 30 min., or so. I now pour 1 gallon of boiling water on the grain bed, give it a good stir, wait another 10 or so minutes, recirculate 3 or 4 times and then check the gravity again. If the temperature corrected gravity gives a reading of greater than 1.015, I will throw another gallon of water and check gravity again. I realize my methods are crude and time consuming, but I still make beer I am proud of.