[bettasusa]

Here is a good home made one I've been checking out and going to start working on and also

http://youtu.be/rj1Glx5anfM (Video)

and also these work pretty well especially for fry tanks. http://www.ebay.com/itm/Bio-Sponge-...ain_0&var=&hash=item80123f55e3#ht_2524wt_1180

 

[bettasusa]

when do I need to replace the sponge?

Like mentioned above, its not necessary but if you want to clean it rinse it in the aquarium water (the one you will be cleaning), and not with fresh water to help keep the bio load in it.

when do I need to replace the sponge? And what should I use in my bottle?

Rocks work pretty well. I like the fine rocks. I also modify it a little with Plastic Canvas (Michaels), to keep the sponge in and also add one of the million hole air stones to make for a nicer quitter bubble. You can add packets, (moms panty hose stuff) of carbon if you'd like too, but its not necessary.

 

[bettasusa]

And any sponge is ok to use right, or should I get an aquarium sponge?

Filler at Petco Petsmart is good. Even pillow filling, The synthetic kind (Batting) I think works from Walmart. Please correct me if Im wrong. Thanks

 

[bettasusa]

Yea for the bio. Just like in the video. He fills the filter with gravel.