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Added on July 20, 2011, 11:09 pm

Wwhat do u mean by: "never putting any medicine during ur WC" is it including that u're also not putting any water conditioner eg: API stress coat?

Else, ur water pH might be too high. For tetra tank with shrimps, the water pH should not more than 7.0

Please check pH regularly if possible.

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Added on July 20, 2011, 11:13 pm

Not necessary, cause ur tank is already cycled with ur filter.... u can put ur new batch of cardinal tetra (but not too much), and try to check the situation after adding the fish.

hmmm.. get some water conditioner or anti chlorine...normal one like nutrafin aqua plus water conditioner...mix it accordingly with ur tap water, let it for at least 24hr b4 u do water change

and more advance one is to check PH, check ammonia... etc etc 

depends on ur tank

let me highlight few points from the web


Granular Activated Carbon (GAC) is frequently recommended for inclusion in aquarium filters.  It is usually manufactured from coal, and occasionally from wood such as coconuts.  It is recommended for use to remove unwanted colors and aromas from the aquarium.

carbon has been used as an agent to remove impurities from air and water. Activated carbon is one of the most effective absorbents currently used. Activated carbon is carbon which has a positive charge added to it, which makes it much more effective at absorbing impurities and chemicals

It does have a finite life, and will usually clog up in about 30 days.  So, when the filter is serviced and cleaned (you DO service and clean your filter… right?), the old carbon should be discarded and fresh put in its place.

However, there are some potential problems you need to be aware of.  Phosphorus, for one.  Some brands of Granular Activated Carbon contain phosphates left over from the manufacturing process, and can add phosphates to the water column.  This encourages unwanted algae growth

The biggest problem with Granular Activated Carbon is that it removes good things with the bad.  Some filters include GAC inside the filter element, and they don’t give you a choice about it.  Such filters should not be used on a planted aquarium.  If you are going to run a filter on a planted aquarium, the best choice is one where you have a choice of exactly which filter material you can put in the box or canister

now imagine ur planted tank is stable, and u dosing liquid fert... and those fert pass thru this carbon.. what will happen ?

on the other side, if u're starting new tank, or u just dose some chemical medicine for ur fish due to some infection/sick ... how to make sure there is no leftover?

 

another thing to add on, activated carbon will NOT remove ammonia, nitrite or nitrate

You don't have active carbon in your filter? One of the main ingredients .

Algae initially are not a bad thing to have, all part of the balanced ecosystem in your tank. It also tells you something about your habits, like too much lights, too much food, too much waste etc.

If you don't have carbon in your filter, I suggest you add this. you can easily put it in a nylon stocking if you don't have the cover mesh, just close it with two small tie-ribs and you are good to go.

Talking about filter inserts. I am looking for filter insert packages for my AquaClear 20 (small hang on filter). Anyone knows a place where to find the filter inserts for that?