i think a much easier mod than the needle wheel with all the sticks sticking out is the much simpler threadwheel... the threadwheel impeller is still not widely available commercially... it comes with bigger skimmers... i think one is the Bubble Master... but in theory, a threadwheel will chop air finer than a needlewheel could...
this is not my picture but this is the pump that comes stock with the Bubble Master skimmer...
this is the one i made...
i made it out of these... i used a paint stripper (inert material of course) to do the mod... you can not use a dish washing scrubber... those things are not strong enough and will shredd under the constant water preassure on the impeller... i simply used the fishing line to tie it to the impeller...
i am using a hang on skimmer... this mod made the skimmer much more effective to the point that the pump is a little too much for my little skimmer... i had to fabricate an enclosed overflow box that goes from the skimmer back to the aquarium because after i did the mod, the water return was causing loud splashing noises and was also taking a lot of the micro bubbles from the skimmer chamber back into the main tank...