False Positives?

[SeanD]

In all my boils, right after firing, the temperature at the draw off spikes a couple of degrees during the really hard boil, but after about three minutes, starts to drop until I fire again a couple minutes later. I'm firing every five minutes, and it's still boiling at the draw off, but just not as hard as right after firing.

When trying to get a sense of when to test or draw off, should I use the low temp. just before firing or the high right after?

Sean