Ok, on my eheim 2028 pro outlet pipe i have placed a max mix CO2 reactor, then the Vectron 300 UV, then up through a Hydor 300 Eth. My worries about whether the filter can handle the roller coaster ride and still deliver a meaningful turnover have been quashed and am seeing a nice level of turbulence through all corners of the 270ltr tank. That's with filter media but without any fishload. I've used hose clips to ensure a nice fit on the UV unit and CO2 reactor. The water driven impeller on the max mix is noiser than the eheim! which is a bit of a downer, but I can't wait to see it chop through and completely dissolve the CO2.
Thanks for all your input
Gary