I use a DIY moving bed filter from youtube http://www.youtube.com/watch?v=K1Wodw8n71Q
I have 2 sponge filters in my 55gal planted with this filter and I never have issues
I bought Hel-X instead of the K1 in this vid but both work great and makes for a great conversation piece
anyway the point of my post is that I havent touched it in aprox 8 months and it still works great I alternate every 2 weeks cleaning my sponge filters every 2 weeks and that's it.
I do 2 20% water changes a week with heavy feeding and never have issues
when I do clean filters I use tank water not tap water
good luck I would recommend this filter to anyone