Recently I had been working on an underwater air cave for crab but she has died during a moult at the age of 2 and half years. So moving on I decided I wanted rid of all the plastics in the tank and to go for a more nature type feel given the volume of java moss I have planted in this small 12L Nano aquarium.
This idea was inspired by PondGuru "invisible filter" on Youtube (watch it here: https://www.youtube.com/watch?v=OIrQ_RWGRKI
). The idea is clever but really only works for bigger tanks so instead I seen a coconut shell in the local pet shop which I seen potential in. It already has a cut out flat bottom and a hole on the side drilled usually to let air out when you place it in the tank.
There's only a few things to do when preparing the coconut shell:
[*] Ensure the shell has no more white in it at all.
[*] Boil the shell to get as much of the brown residue to leave the shell that normally tints your tank water.
That is all really for preparation.
To use carbon in the coconut shell without it floating around and escaping I used a new pair of stockings, cut the legs to make a stretchable ball filled with carbon pellets. A simple knot at each side works with the excess trimmed off.
With the carbon ready to be used you can see the stacking order as it will be placed in the shell. At the top is a very fine "polishing" filter which scrubs the water of very small particulates. The carbon in the middle with a "normal" filter to catch the larger pieces of dirt.
To secure the coconut shell in place I'm using one large sucker pad which goes into the original air hole on the side. I drilled an extra 6mm hole for the air line to run in and that itself has two sucker pads which help pin down the shell and tidy up the piping.
Inside you can see the cylinder type air stone I'm using. This gives a large volume of tiny bubbles which displaces more water than large bubbles.
Looking past the air line you can see the 5 exit holes all 4mm each stacked with 3 in a row and the last 2 between them just offset too them. The last thing you want is for the air to begin getting trapped and lifting your shell off into the tank lol.
It is now time to start adding filter medium!
So you can see how I've filled the inside level to the air-stone so its just matching the top (from camera perspective) of the air stone.
Remembering we are working backwards the next filter is polishing filter that will scrub the water last before the bio-media gets the water passed over it.
In the middle goes the carbon filled stocking which you can see due to the material allows me to stretch it out so it fills out to the inner shell.
The last filter is the normal one which pops inside to close the gap and become the first contact point with water flowing inwards.
I can't emphasize how much I like the final look, the water needs to clear a little but you can see well enough.
All the male Guppies and shrimp love playing in the bubbles. The shell exterior makes for an excellent natural filter itself catching all types of bits out of the water which the shrimp and fish alike can feed on.
It really is an all round win - win set-up :)
Cleaning the filter later in time due to the way its put together is a fairly simple job of disconnecting the air line at the valve above the tank and pulling the shell out then repeating the above process.