This is a planted filter I set up in a window. Its nothing fancy. So far after two months all the water nasties have been zero. This is a 5 gallon tank filtering a 20 gallon with a fairly light fish load. The 20g has 6 dwarf puffers and a bristle nose. The 5 gallon also serves as a snail jail for the puffs.
The plants in the 5g are water sprite and anacharis. In the 20g I have some java lace and moss under 15 watts of light.
Again nothing pretty but it does its job. The pics show it full of algae mainly due to it getting a lot of sun. I'll be adding some shrimp to help the snails kept the algae down as much as possible. But as long as there is no algae in the main tank i'm happy.
5g was built out of some fire place door glass I bought at a thrift store for about $2. Since that glass is tempered I went to the hardware store and bought some float for the end pieces about $0.50. Then glued it together with some ge silicone 1. Unfortunately the plumping is were I took a hit. The tank is 8ft away with a 2 foot head and my girlfriend said it had to be somewhat nice looking and well hidden. So lots of elbows (10 for going to the 5g and 7 for the return), bad for flow I know. The plumbing was about $25.
Everything else I had lying around. Power by a fluval 104 with only mechanical filtration pumping water to the 5g, then water is siphoned over the edge and gravity fed back to the main tank. The top pipe over the tank wasn't suppose to look like that. I found out that in the event of a power failure, the pipe will siphon half of the water out if the pipe is in the water. So it has a temp fix.
So far its looking good for never having to do a water change. I'll give it a couple more months before I officially make that claim.