[zzyzx85]

I have two 2215 filter and I remember reading somewhere that it's recommended that you replace 50% or so of the bio media (ehfisubstrat/pro) every year or every so often.

I was wondering what's the reason behind this. Is it only because the pores of the media get clogged up or is there another reason?

Personally, I think this is quite excessive/expensive. All I've done with the bio media is give it a good swish in old tank water. It knocks loose a lot of the gunk that builds on it and it comes out cleaner than when I put it in. I might just buy a gallon or two of plastic bio balls to replace them.

 

[zzyzx85]

figures it was $$$. I do have a ehfisubstrat that is starting to decompose so I might split up the ehfi pro between the two filters and buy some bioballs. I would use those potscrubbers but I can't find them at the 99 cent stores anymore.