replacing bio-filter media

[babygeige]

I've got a question about biofiltration media. I use bio-chem stars in my canister filters. API recommends replacing half of them every 6 months. Why is that necessary? I rinse them off every month when I clean the filter out and they don't get slimy or anything. In reading Carl's article about filter media, it seems that clogging and sliminess is more of a problem with ceramic rings.

I was thinking about trying a different type of bio-filter media (volcanic rock or Sea chem Matrix), but it seems like the bio-chem stars are just fine for my purposes. I have plants, so I don't think I need to worry about de-nitrifying media.
I was just curious as to why they would need to be replaced every 6 months.

[Carl]

The reason API suggests this is that the surface that the bacteria cling to tends to get more "slimy" over time allowing for less space for the desirable bacteria to colonize.

A good way to visualize is if you have a sponge filter that has been used for some time, you will note that it does not rinse out as well over time and gets more spongy/squishy.

This said, your bio stars (& sponges) still are working just a bit less over time.
Also I think 6 months is a bit aggressive under most aquarium conditions; I generally only change out 25-50% per year.

Carl

[babygeige]

Thanks for the explanation, Carl. That makes sense.
I generally don't follow the recommended media changing times on product packaging for most things. I just wait until something seems like it needs changed (like foam filter pads), but I wasn't sure how to determine that with the bio-chem stars. It's probably been about a year since I've changed them, so I suppose it won't hurt to swap some out with fresh ones.