Not sure which comment you are questioning.. but, yes, in some cases the Wal-Mart and Intex filters simply allow too much of very small particles to flow thru the filter. I am guessing here but I would think that these filters are effective on debris in the 10-20 micron range. A micron is a unit of length equal to one millionth (10-6) of a meter.
This means IF the stuff in your water is larger than 10 microns, the filter may be able to catch it and remove it from the pool. If the debris is smaller than 10 microns, say 5-9 microns, it will come into the filter, pass through the filter media, and flow right through and back into the pool... always. Better cartridges may be effective to 2-5 microns in size.
DE filters, so I have heard, can be effective down to 1 micron. This means they can trap all debris in the water that is larger than 1 micron in size.
I mentioned you can add Diatomaceous Earth (DE) or cellulose to the filter. What this does is that the larger DE and cellulose particles are trapped on the outside of the Intex filter media and they create a fine layer on the filter media, the DE layer on the Intex filter then acts as a filter itself and starts trapping particles from your pool's water. The problem is, the DE itself is blocking to flow of the water as it leave the pump and the pressure increases and the flow decreases. So, the filter works better but it slows the number of gallons that pump is able to pump. This means if the pump was capable of pumping 1600 gallons per hour at 0 pounds of pressure, this is decreased to 800 gallons per hour or less at 20 pounds. Cellulose is an alternative replacement for DE but it works in a similar way as DE. When you remove the DE and debris covered filter, you can wash off the junk (and DE) and use it again until the filter no longer filters effectively. If you re-install the filter you used with DE, you will need to add DE again to re-coat the filter.
