A cost-effective replacement for the carbon in your tank is a UV filter. The start-up cost is a little high, but the bulbs last about a year and are guaranteed to protect your tank from algae, ich, and most other nasties.
If you're using disposable filter cartridges and you're concerned about the cost of replacing them, you can generally clean them, cut them open and empty the carbon out and replace it with an equal amount of "activated aquarium carbon" available in most areas. It's pretty cheap if bought in bulk.
Good luck!
If you're using disposable filter cartridges and you're concerned about the cost of replacing them, you can generally clean them, cut them open and empty the carbon out and replace it with an equal amount of "activated aquarium carbon" available in most areas. It's pretty cheap if bought in bulk.
Good luck!