Home Made Air Bubble Filter

[LilyRose Tank]

following instruction from Lilfishie ( thanks babe) I have made a home made filter using the neck of a cola bottle, gravel, stones, and 3 filter sponges ( 1 carbon, 2 normal) with an airstone setup at the base. I am chuffed it works. I just hope "Ice" my new poorly betta, makes it through .

can someone tell me if i have made the filter correctly.
upturned botttle neck , placed airstone at bottom, inch of gravel and a large stone, to weigh it down, 3 filter sponges on top with another stone to weight it down
the top of the bottle is 2cm below water surface

 

[LilyRose Tank]

Ok, I had another attempt at this with a more stable bottle. from the bottom up, airstone ( fed through a hole made at bottom of bottle), gravel/sand mix, carbon sponge cubes, filter sponge cubes, gravel sand mix....much more stable