I decided to try what was suggested to me. Use the same filter bags folks are using to allegedly increase filtering capabilities. It seemed to make sense.
A sand filter goes down to typically 20-30 microns, right? Some folks (based on threads I've searched) seem to think that putting a 1-5 micron bag onto their return hose gives them DE-like filtering. I now seem to have evidence to refute what I already felt was BS.
If a 5 micron bag filters debris that passes through a 20-30 micron sand filter, then I should be golden if I use it to filter backwash water as I shoot it back into the pool.
I sealed off a Duda Diesel 5 micron 14" bag onto my return hose and pointed it back into the pool. I ran backwash for about 3-4 seconds without a problem. Then all of a sudden a brown cloud started coming out of the bag. No, it wasn't a leak in the seal. The cloud was evenly distributed out of the whole surface area of the bag.
Fortunately I yanked it out after about 3 seconds of cloud generation.
So I'm wondering what went wrong. Do the bags not really filter to 5 microns? Do they filter to 5 microns when the liquid passing through is either at gravity or slightly above and the flow from a pump is too much and the PSI pushed stuff out? Do I need to buy the much larger/longer bag to reduce PSI/sq-inch?
Based on the results... with higher volume pumps are people who think they are getting superior filtering really experiencing something that's all in their head?