Two questions??

First of all, are you actually catching any fish with the size 20 emerger ?? If not, why bother with it ??

Second, are you catching fish with the p.t. ??

Sounds like the p.t. is attracting the fish to it, but they aren't interested in eating it. After they take a look and refuse it, they are getting snagged by the dropper.

I would think in terms of fishing a smaller p.t. and, if you still want to use the emerger, lengthening the tippet between it and the p.t.

Another thing I would consider would be going to a weighted caddis larva pattern trailing the p.t. rather than the emerger. It seems that down on the bottom, the fish would be more likely to go for a good larva pattern than a small emerger ??