A Few Newbie Questions

Is this the filter http://www.zooplus.co.uk/pictures/product/Manual%20Tetratec%20EasyCrystal%20Filter%20250.pdf

From what I can gather via google, it has :

Physical filtration: Double-layered Filter Floss Pads reliably remove even the tiniest particles; White side = coarse pre-filter, green side = fine filter

Biological filtration: Filter Sponge and organic filter balls with an extra large surface area for the settlement of beneficial bacteria

Chemical filtration: Special activated carbon to eliminate water clouding and unpleasant odors

The manual shows just 2 media components - are the physical filtration (double layered, white on one side, green on the other) and the carbon together in the cartridge? It is common to put carbon inside a cartridge made of a 'bag' of filter wool on a frame, and I presume yours is like this?

If I'm right, leave the sponge there, just wash it in old tank water during a water change until it falls apart or won't go back to shape. As for the cartridge, if it is carbon sandwiched between the white and green surfaces, make a tiny slit in one side (the one least likely to fall apart) and empty out the carbon. Then either just leave it in there empty, or try and fill it with slices of sponge. Or if you prefer, repalce the whole thing with a sponge cut to the exact size of the cartridge. There will be some bacteria in the cartridge, you'll lose some by getting rid of the carbon, and you'll lose a few more if you replace the whole thing, but if you do it now when you don't have that many fish in the tank it won't be as bad as doing it later.

Or you could just leave it there and never change it. The carbon will be saturated by now and will have stopped working, but it does provide a home for the filter bacteria, just not as good as sponge etc. You can leave it there forever if you want, just wash the muck off the surface when it builds up. The only possible downside to this is if you ever need to treat sick fish. Although the carbon is saturated, there is the possibility that the medication will be more strongly attracted to the carbon than what's on there now, and will push the other stuff off and stick to the carbon instead, rendering it ineffective. The choice is up to you. I would remove the carbon, but that's probably just me being over fussy. The majority of people don't have a problem medicating a tank with carbon that's been there many months or years.

You don't need carbon. It's a hangover from decades gone by. It's uses are to remove the brown colour from bogwood, to remove medication after treatment has finished if you ever have sick fish, and to get rid of any odd smell, which I personally have never had.
The other part of the cartidge is mechanical filtration - but sponges do just as well. If you fill/replace the cartridge with a fine sponge, that would be better than a coarse sponge from a mechanical filtration point. You can use any make sponge, just cut it to fit.


Snails are not the problem a lot of people make them out to be. I have tiny flat red snails in my tanks, as well as the nerite snails I bought. They only become a problem if you overfeed the fish. For ID have a look here http://www.planetinverts.com/


Naughty, buying more fish  If you change/swap the filter cartridge I'd wait until you are sure the bacteria have caught up with your current fish and shrimps before getting more. If you decide to leave the cartridge there untouched, you should be OK to get another couple of fish. Don't forget to check the ammonia and nitrite levels after, and then after a least a week of double zeros, you can get more. The fact that your shrimps are still alive is a good sign as they are more sensitive to poor water than fish. Get a couple more of the same type of shrimps at some point too, they also like to be in groups.