I've got an Elite Stingray 15 filter in my tropical aquarium, which has been set up since late November.

I've been rinsing the foam from the filter once a month, using water from the tank when I do a water change.

I haven't done anything with the carbon filter cartridges at all.

I'm new to keeping fish, so I just want to know if I need to replace the carbon cartridges and/or the foam? If yes, how often should I be changing them?

You can use the foam until its falling apart, so that doesn't need to be changed often. The carbon will only last a few weeks before it's ineffective so that needs to be replaced on a regular basis...

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20 gallon long:Amazon Swords, Ruffle Swords, Red Flame Swords, Fanwort, Wisteria,8 Lemon tetras,
6 otos, 11 Amano shrimp, 3 mystery snails, 3 Bolivian Rams, 3 black skirt tetra and 2-3 lemon tetra fry
10 gallon: 30 lemon tetra fry, give or take...1 gallon Anubias, Fish: 1 betta

That really depends... do you have live plants in your tropical aquarium? If so, you may want to just take the carbon out and leave it out, as carbon will take the nutrients your plants need out of the tank.

However, leaving it in could end up leaching the stuff the carbon has removed back into your tank, thus giving you the opposite from desired effect!

I believe general knowledge says to replace the filter cartridge every month or so. BUT - if you're interested in knowing more, here is a good page with info on using carbon in an aquarium:

Using activated carbon (charcoal) in the aquarium

and an excerpt:

I never use carbon, but while I don't know the brand of filter you have, if there is room - use the carbon slot for more sponge.
The sponges for most filters are good for years - I have ten year old Aquaclear sponges still going strong.

Personally I don't use carbon in my filter unless it is after using medication or if you want to remove any other contaminate from the aquarium. I would use the extra space in the filter for biological media such as ceramic stars etc. You also should remove used carbon from the filter after a period of time or it will leach the stuff it removed back into the aquarium. Hope this helps.

Carbon looses it effectiveness after about 2wks.

Thanks for all the replies. The consensus seems to be that I don't really need to bother with carbon unless I'm looking to remove unused meds from the tank.

And that I should replace the carbon with either more sponge or some ceramic stars. Which is best? I'd never even heard of ceramic stars until now! Do they fit in all filters or are they specific to a certain make of filter?

I have no idea on stars, but I do like the idea of changing with more bio media. It can be in just about any form. Aquaclear sells their bio-max stuff in Petsmart.

Carbon is useful in keeping water clear. It can remove microscopic particles that cloud water. If you leave it in too long it stops working this way but continues to work as a biological filter. Be aware that changing and cleaning filters removes bacteria from your tank. If done at the same time as vacuuming, it has the potential to remove too much and cause an ammonia spike. That's the theory anyway. This has never happened to me.

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Live Coral and Care Instructions at aquaticcastle.com

In my filters I use a sponge, biomax and an old carbon pouch. I was changing the carbon monthly, but really, it wasn't doing much for the tank. I've got it in there still, acting as bacteria space, but I should take it out and just put either more sponge or biomax there.

The sponges rarely need to be changed (unless falling apart or not keeping their shape), same with biomax. I just squeeze them out in the dirt fish change water either monthly or every 2 months - to keep them unclogged (live plants tend to gunk up the filters a bit more.)

Then, usually monthly or every 2 months I will clean the intake tubing and impellar of my filters, to get the gunk out, because they do become clogged. I don't scrub them super clean, but just get the big pieces out. I rinse the housing of the filter in the dirty fish change water as well, because I do notice that bits of plants and other debris tends to build up at the bottom.

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20g Heavily Planted http://www.aquariumforum.com/gallery...00&ppuser=8981
36g Bow Front Heavily Planted http://www.aquariumforum.com/gallery...00&ppuser=8981