excessive bubbles in Ca reactor

[fishface]

can anyone tell me what i may be doing wrong here. seems like i just keep getting way too many bubbles built up in the top of the reactor. i have to open the effluent valve all the way to vent it so effluent can flow again. seems like it happens every morning. drip rate is about 50 dpm and bubble count is about 50 bpm.

greatly appreciate any ideas to help me out here...