I don't quite agree with that, Veg will pull through a load of crap mark my words
I've opened a filter up after I left it to dry in the shed for a few weeks in the garden and the crap that was in there was unreal and it had only been on the car 2 months before the first ever tank of veg that I used.
You'll know when you need to replace the filter as the car will start juddering, at first you will crap yourself and think it's the end of the world and then eventually you'll just shrug it off and think, "meh, I need a filter change soon" lol
As for ones to avoid, Boshi ones are the worst!!!! I found Blueprint ones very poor as well, the best ones I've found at £6 a piece from my local motor factors are the Comline ones (blue in colour)
Replacing them is pretty easy mate, with the right tools at hand I have got a filter change down to 15 minutes
Tools needed;
Ratchet and 12mm Socket
Filter Wrench (Avoid at all costs the chain ones) -
http://www.buckandhickman.com/find/product-is-2014266?gclid=CL6T1J2Hi7wCFSsCwwodQBYAVA
Bowl to empty contents of filter into
Diesel to top new filter up with
Remove x2 12mm bolts from filter primer and then remove plug from bottom of screw in water drain off plug this will allow you to slip the wrench onto the filter, once it's on, drop your bolts back in to give yourself something to lever against to free the filter, once you can spin it by hand remove the 12mm bolts again and unscrew the filter from the housing, pour your old fuel into the bowl, once its all out, then remove the white screw in water drain off valve.
Get your new filter and fit the new seals in place, attach the water drain off valve again and then fill the new filter just over 3/4 full with diesel, carefully screw back onto the housing as tight as you can by hand and then attach the wrench again, 12mm bolts in again for leverage, tighten, remove 12mm bolts, remove wrench (optional - I leave the wrench attached to the new filter ready for the new filter change, as long as it's tight there's no harm leaving it there), plug back in water drain off valve plug.
Once you've packed your tools away, you'll need to start pumping the plunger by hand on top of the filter housing, it will be very spongy at first and will eventually get very firm, I am lazy with this and end up pumping it for a few mins and then turn the car over and while it's running then prime the plunger, this does make the car run slightly lumpy until the plunger is firm but you're making the fuel pump do all your work in essence
Once it's rock solid and you can't depress it anymore and the car is running smooth, go make yourself a cup of tea, you're done