From the growell site (more in their paper newsletter about this):

"We now recommend
that you change your Grolux lamp every crop for maximum efficiency. The cost
of a new lamp is less than you could lose in yield by not changing."

(They go on to say that the higher output/different spectrum ballance of
Grolux type HPS tubes is at the cost of lower lumen/life than 'std' HPS, as
they have proven it to themselves with testing.)

Hype to sell more lamps, or anyone else found this too?

These hangers - look good to me and only