Here are some remarks from Tasty that I've copied from the BN Forum:
"I use the 6-side plate filter that's available from various retailers. I bought mine at morebeer: http://morebeer.com/view_product/5676/
I use the 7 micron filters that I can only find at Williams Brewing. I've tried lower microns with marginally better results and unneeded problems. I found that with 7 microns and reasonably clear beer (2-7 days at 35F works), I can filter 10 gallons with one pair of filters. I pretty much follow the instructions that come with the filter. Things they generally don't mention are 1. flush the target keg and filter housing with CO2 2. run some of the beer off from the source keg until it's clear. 3. When filtering two kegs, don't let the dregs from the first keg go into the filter. 4. Never leave the area where you are doing the filtering because you will eventually forget and find your finished beer all over the floor. And if anyone ever tells you that filtering strips flavor and color, tell them "Mike McDole said those are recipe issues".
Here was a question by DannyW followed by Tasty's reply:
DannyW:"I wonder if those pads are really 7.0 micron, or are the 0.7 micron? I see the William's brewing site says they sell 7, 3, 1 micron. Morebeer sells "rough" (2 micron), "polish" (0.7 micron) and "sterile" (0.35 micron). I have a sneaking suspicion that they are actually the same pads, but perhaps William's pads are showing absolute and the B3 pads are showing nominal? I know I have been able to push 10 gallons of beer through both the B3 rough and B3 polish filters without much trouble."
"You may be right about the absolute vs nominal micron differences in filter ratings but I know for sure that the Williams filters are about 25% thicker. I feel that I get a better seal with that extra thickness. It may be psychological though."
"I only use the 3 micron pads when the 7 micron pads fail to clear the beer. That usually implies some sort of protein/tannin and unless the beer is for some special purpose like a friend's wedding or competition, I usually just leave the haze, apologize every time I pour someone a pint, and fix the problem in my process or ingredients. (I'm talking about the pads from Williams here. The last time I used MoreBeer pads they were similar but different.)
When I say to adjust the recipe if you feel filtering has an effect, I'm not saying that's an analytical adjustment before you make the beer but instead a subjective adjustment after you taste the filtered beer. If the beer lacks bitterness, aroma, mouthfeel, or whatever, adjust the recipe or process accordingly. When someone gives me a recipe and I know they don't filter, I never make any adjustments because I feel that filtering has no effect on what I like in beer. I don't have any science but I really doubt that anything good in beer is larger than 7 microns. When someone puts a $5.50 pint of cloudy IPA in front of me, I have to wonder why the brewer would want that stuff floating in there to leave the brewery. I definitely don't want it.
So whether is finings or filtering, for me, it's not beer until it's clear.
"Have you ever noticed any oxidation being introduced from the filtering process, or do you do anything special to mitigate it? I haven't but LHBS people were warning about it."
"Certainly oxidation introduction is the largest risk with any transfer and a filter adds a lot more points of failure. I'm always watchful for bubbles appearing in the transfer tubing. It's easy to assume it's CO2 that has naturally dissolved into the unfiltered beer. There's a plastic "Y" connector that joins the two outbound sides of the filter. I recently heard from a brewer who had a crack in his and was oxidizing all his beers. Not what you want to be doing in the final steps of making the beer.
I always flush the filter with CO2 right before starting the filtering process. I also run about a half pint of beer out into my dump bucket. I rarely use fining agents. I generally store the racked beer at 34F for a week so by the time I filter, it's pretty clear (not bright) to begin with. 7 micron seems to give me just the clarity I'm looking for."
"Cartridge and plate both have their advantages and disadvantages. I'm open to both and have used both. I always go with whatever requires less work and the least chance of contamination unless there's a substantial cost factor.
In terms of does filtering effect flavor, of course it does. If it looks different it probably is different. Can you perceive the difference and is it enough to call for a recipe change? Filter half the batch and do a blind tasting. I've done it and the filtered beer always tastes better to me. Of course, I'm looking for a clean unobstructed bitterness and malt backbone so you would expect I'd like the beer without the yeast and protein."