Wow great advice, my jewel filter system is made up of 5-6 different sponge filters and I only replace the slim white filter weekly, which is advised in the manual to do so, all the rest just get a squeeze/rinse out in the old water that I have taken out. Again advice I have followed from the guys in the aquatic shop.
link to what the filter system looks like:
http://www.aquacare.co.uk/filter_assembly2.jpg
I hope this is correct? It seems to work as the levels are are fine and the fish look well.
kimb - yes I only rinsed it, well, stuck it in a bucket and did a few water changes.
Will read up on tannins, but I have noticed the plants are doing really well in this tank, so I guess its ok for the plants as well.
I quite like the colour (color for you US guys ;-) it does give the tank a mysterious look to it and as long as it does not harm the fish I am not too worried to be honest.