Yes, others have noted increased PSI using Vertex diffusers. This is probably why Vertex uses rocking piston compressors that can easily 'handle' this extra PSI needed by their specially built diffusers that regulate the air flow to multiple diffusers.
Here is the lengthy discussion where this was discussed in detail.
http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=373358&page=2One good and easy way check the PSI back pressure is to set up your system completely out of the water. Start the compressor. Read and note the pressure gauge. Now remove just the diffusser/s. Read and note the pressure gauge. The difference between the two PSI readings is the back pressure created by the diffuser/s. Using the 0523 rotary vane compressor with a single straight manifold, I hooked 400ft coil of 1/2" black polyethylene tubing (5/8"ID) to the pump. Air gauge registered 0 psi.
