Slau,
I am no expert but IMHO i would immediately slow down on the
overhead watering, that will have a
big effect on the sphagnum growth... trim the sphagnum as much as possible then I would foliar feed with cotton swabs, (this will help slow any further algae growth resulting from spray foliar feeding and help the ceph's growth rate).... i use a weak orchid mix once or twice a month... I apply to the outside of the pitchers as well as the leaves.... about two weeks later you will notice a surge in growth
if that doesn't do it, then you will have to do something more intense
some of your sphag looks like S. squarrosum to me, probably one of the most adaptable and toughest varieties...really nice stuff but it will outgrow your ceph given half a chance
Av
comment: Slau, look at the ceph pics that have been posted lately... in most you will notice the sphag has brown or black tips... that is a result of not enough water for the
sphagnum to continue to grow, puts the sphag in sort of a dormant condition it seems, alive but not actively growing.... but what works for one doesn't always work for another... cephs seem to have their own personalities sometimes
I try to keep the sphag tips black or brown not "dry and white" nor "green and growing"