Pre filtering keeps costs for reef tanks way down, but there is work with them.

There is only two ways to keep pre filters looking after your reef tank affectively and there are a heaps of them out there that do, "not enough", most do a little, but that is not enough for the long term and seriously help reduce costs!
Better pre filtering- far less phosphates and no need for products like GFO to name one.
Better pre filtering- nitrate reducing areas do not get chocked, resulting in far less parasites.
Better pre filtering- reduced hair algae and cyanobacteria and much more.
 
For the only styles of pre filters that really do it, as in pre filter out rubbish to protect the biological media, the material micron that works best needs to be there and the two forms of pre filtering need to be there, in some kind of design!

The two that work best.
1) A large surface area barrier as your water first leaves your tank, large so that the water moves through slow to enable catching organic matter, silica based shed shells and calcium particles from anything dead or as waste and that includes shedding algae or dead algae, it is chockers with calcium! this one is cleaned each day, if not at home for days, its fine if rarely done this way.

2) The next can only work with one design only and that one requires little work in cleaning. It is a large surface area that is not hit by the direct current and is cleaned once water to the tank has been off for a few minutes, this enables nothing in any form of organic or inorganic form to get past.
What media is after all this, with no lighting, will never receive anything capable of blocking bio media whether it be aerobic, anaerobic and metal reducing bio sinks, all a must for a reef tank to go on for ever, with little costs.

Pics of first barrier of one day of rubbish build up


Cleaned