-The problems with the pellets regarding not tumbling , lies in the fact that the reactors all have some kind of filtering pad on the overflow / output of
those reactors.
These pads will get saturated with bacterial detrius and thus reducing the flow , also when just starting up an reactor and the flow is too high the tumbling pellets will also plug the top pad and reduce flow tru reactor and stopping the bottom pellets from tumbling.
I think an open reactor or overflow vessle is the answer to these kind of problems , mine is just an DIY overflow box 2.5" X 2.5 " and 6" high with an open overflow @ 300 to 400 G/h.
my pellets keeps tumbling happy w/o any problems.
greetingzz tntneon