water question and sick fish trouble

[duck]

Hey all.. my fish tank is up and running well.. however I am losing a fish every week or so... I am doing 20% water changes every 2 weeks... I have a planted tank... feeding the fish one time the first day then the next feeding it twice using flakes and then pellets on the second day. I have good filtration... good areation as far as I can tell and I am checking the water using test strips and the only thing I can see "wrong" with my tank is the water is really hard... What can I do to get this softer.. I use some water conditioner aquasafe every water change to get ride of (it says) chlorinates and excess metals....
could it be something else.. is this a really "bad" problem?

The fish start just getting slow and lathargic.. swim funny then in circle.. then they act disoerntaded and die... never floating to the top normaly resting at the bottom.. this may take a day or two ....

My water temp is maintained about 74 degrees.. no cloudiness or algea...
the fish never look like anything wrong.. nor visual warnings or clues....

I have tiger bards and one algea eater .. so far one normal tiger has died and one albino.. both came from walmart .... but then agian so has all my other fish and they all look fairly healthy.

[Leopardess]

How long have you had the fish? If you bought them from walmart (and anywhere else, really) they may have been sick when you got them.

A big red flag is your maintenance routine. IMO 20% every two weeks is def. not enough. Try upping that to 30% a week...or even 20% every couple of days.

Did you cycle the tank? do you know what your nitrates/nitrItes/ammonia readings are?

Also, you probably don't need to worry about softening your water.

Are you fertilizing your plants?

I'd suspect its due to high nitrates, an uncylced tank, or just because the fish are new and some can be expected to die (cough...especially when they're from walmart...cough;))