sick fish and algee bloom??

Question
I have a ten gallon tank with 2 platies,2 red zebras, 1 pleco it's kind of a rusty red color, and 1 crown betta, we noticed the day before yesterday that the betta was laying at the bottom of the tank, now his fins look just a little ragged and clamped?? it looked like his face had a little yuck on it so we looked up different sickness and nothing looked close, but this morning I think I see a couple white dots, ich?? he is out of the tank in a vase but from what I'm reading the rest of the tank will have it also?? and to change the water, totally?? and to add fish salt and treat with aquarisol also our tank is cloudy, bloom?? they said some thing about changing the filter too often and leaving some charcoal in the filter I use whisper but my cartridges are all enclosed should I be using a different kind? should I just put the betta back in and raise the temp and treat everyone together? thank you for your prompt answer, they are my 7 year olds sons fish and he is upset with me (like I made them sick) I don't check water ph and such

Answer
For the sounds of it you have high ammonia.  The ich is probably a secondary infection.  If just the betta has ich, I would leave him separated and treat just him.  For the rest of the tank raise the temp to 80 for 3 days and do a 25% water change every day for the same 3 days.  If you change your filter cartridge on your filter, leave the old one sitting part in the filter for a day or so.  Most of the bacteria that filters waste lives in those cartridges.  When you take out the old one, you are taking the tanks biological system away, then it takes a few days for the tank to recover.  If you leave the old cartridge in it "seeds" the new one.  I personally only replace the filter media once a year or so.  When you change the water from your tank, just rinse your cartridge in water you removed from the tank.  It will "clean" then media so that the water flows better, without killing the bacteria.  It also saves money.  To avoid this problem in the future, I recommend a 10-25% water change every week and seeding your filter media if you change it.  I hope this helps :)