Grrr. My biopellet reactor died

[Stones]

I assume this is the reactor that you are talking about? This is obviously a design flaw having such a small outlet for the effluent. Most reactors come with 1/2" or 3/4" outlets and even those can fairly rapidly narrow due to build up of bacterial mulm.

If you have access to some NPT taps, I'd remove the factory john guest valve on the top of the reactor and drill/tap a new hole large enough for at least a 1/2" threaded PVC elbow. Then you can add a 1/2" ball valve to control the effluent rate and by increasing the diameter of the outgoing plumbing, you should no longer have to worry about plugging off solid any more.

My biopellet reactor went anoxic and smelled the same way after I forgot to turn the flow back on after a water change. I removed all the pellets and let them soak in RO/DI until the sulphur smell had dissipated. All of the bacteria obviously had died but the pellets started working after a few good does of MB7.

By the looks of it, there isn't much you can do to help alleviate the clogging screen for the recirculation part of the reactor. My only suggestion would be to cut a circular piece of needlepoint plastic (available at places like Michaels) and wedge it in the reactor just below the intake screen to help prevent pellets from circulating that high up in the reactor.