Pond Boss Forums AERATION Systems questions Kasco Robust aire Diffuser

I have the Kasco system with 6 diffusers and this week I noticed the bubbles at the farthest diffuser was not bubbling like it should have. So yesterday my grandson and I pulled up the diffuser from 12 foot water depth and scrubbed the tubular part using a brush. Hope it helps. The running time was in the shut off mode so not sure at this time if it helped. I hope so because if not I will have to track down other possible problem, if any. First time this diffuser was cleaned since last year. When I started the system up earlier this year, I just forced more air to each diffuser by closing off the air the others. And hoped that would clean each one up. All but this furthest one seems to be doing well. Remember, I am moving air around 2,200' to that farthest diffuser.