i've just started to re-set um new filter in all of my pleco-tanks
i used a 6mm glass glued it simply in the tank. i've cut a corner out where the glass meet the silicon (in the corners)
![Image](http://thumbimg.img-box.de/7/6/9/8/4/76984.jpg)
for bigger tanks you can simply add another wall and squeeze a second sponge...or a third and so on...or set up another filter on the opposite side of the tank...
a second small glass peace on the bottom part keeps the sand out of contact with the mat. so i can easy clean the mat without having to deal with the sand/gravel.
![Image](http://thumbimg.img-box.de/7/6/9/8/5/76985.jpg)
the mat is cut 5mm larger so it squeezes well between the two glasses
![Image](http://thumbimg.img-box.de/7/6/9/8/7/76987.jpg)
+
1. easy to make not the cheepest version but as long you have the glass in stock ;)
2. easy handling and maintain...
3. view inside (small fishes,heater controle, bakterial/waterlevel etc...)
4. saves space and still hat a big surface for bacterias
5. also well uitabl for bigger tanks
the glasswall ist 9-9,5cm wide
airsystem run...http://www.luftheber.com/tschechische-luftheber.html (in german sorry but you get an idea)
![Image](http://thumbimg.img-box.de/7/6/9/8/8/76988.jpg)
this for example is my Hypancistrus zebra tank...
in my 900L tank i use the same system just with bigger surface and bigger airpipes...
http://veloofahren.ch/Aquarium/L90.htm
rgds
farid