Hi all,
They (the Schuran 100 multifilters) are quite expensive. You can make a much cheaper quiet trickle filter by using a column, packed with biomedia. I used drainpipe packed with "alfagrog" or "hydroleca" sat on a mesh in the sump, but a bucket with a lid and holes in the bottom filled with pan scrubbers and sat on bricks would have done. You need to vent the column/bucket, even if you are attempting to restrict gas exchange, and tall towers are much better than short towers.
You also need a drip plate, I used a 2 litre container pot (it fitted snugly in the drainpipe), but you can make one from plastic , the important thing is that the holes around the perimeter are larger diameter than those in the inner area. The advantage of the pot was that you can fill it with coarse foam as your mechanical pre-filter if you don't want a sponge in the tank. I also built a baffle into the sump to isolate the pump (usually a maxijet), but that isn't really necessary. The other thing I found was that the overflow from the tank needs to be less than 1/2 of the diameter of the outflow from the bottom of the filter, or flooding is likely.
I stopped using them because I went over to the over-tank planted trickle filters, these are even more effective in terms of producing highly oxygenated, very clean water, even when you start with grossly polluted "water" with a very high BOD (I wanted to remove as much nitrate as possible, which is one advantage of the planting, if I hadn't wanted to remove it, I would have stuck with the sump version).
Have a look at this <
http://leisure.prior-it.co.uk/trickle-filter.shtml> or this <
http://www.aquariumlife.net/projects/diy-filter/111.asp> it explains the bits you need to know ,this link also has some criticism of the latter design <
http://www.reefsanctuary.com/forums/diy/55805-looking-diy-wet-dry-trickle-filter.html>.
This is another variation on a theme. <
http://www.theoscarspot.com/viewtopic.php?f=30&t=20243>
cheers Darrel