Newbie - New aquarium

Question
Ok, the person I had asked my question to earlier is not available, so I will re-post my question and briefly give her response.

My question was:

Hello,
I am a newbie at fish keeping and I recently purchased a 10 gallon aquarium at a pet store, who then sent me home with 2 small bala sharks (after researching them couldn't believe they sent me home with them and a 10 gallon tank!).  On day 4 while checking on the fish, I thought I noticed a piece of white cottony stuff coming out of one of the fishes mouths.  But when I kept looking I didn't see it anymore so thought I must have been seeing things.  So, not sure what happened but on day 5 I went to check on the fish first thing in the morning and one (the one I had seen with the white cotton near the mouth) was not able to stay upright and swim, he kept flipping over on his back.  So, I moved him to quarantine in hopes of not getting the other fish (I know, probably way too late!)sick.  While in quarantine, I noticed the white cottony substance again, it was actually IN his mouth and would go in and out while he breathed at times...  At any rate, I thought I would get on the computer and investigate so started my computer up and got in the shower.  When I came back, the fish that I had left in the aquarium (that seemed fine) was dead.  The one in quarantine was obviously not long for the world and when I got home from work he was indeed dead.  When I looked at him, he had a large patch of scales missing off of his underside.  So, I guess my question is, I am uncertain if my water quality was the problem with the fish dying or if they had some type of disease.  I am unsure of my next step to try to get the aquarium off the ground.  Should I wash it out and start all over again, or let it go and keep the cycling process going.  Tomorrow will be one week since I set the tank up.  I would appreciate any help you can give. Thanks

Her response was that it was hard to say what went wrong with the fish (other than obviously I wouldn't be able to keep those kind of fish in a 10 gallon tank when the grew - they were only about 2 inches long at this time).  She suggested I go ahead and do fishless cycling, but I am unclear as to if I should empty and clean out the tank and then fishless cycle or if I should let the tank continue now (since I did have fish in it for 5 days, but I am uncertain if they died due to water quality or sickness).  If I am supposed to empty and clean the tank, please let me know what I should clean it out with, and what about the filter and bubbler and stuff?  And one more probably stupid question, but after I do eventually get some fish in the tank, how do I do water changes?  What I mean is, does the temperature of the water have to be the same as the tank and, if so, how do I get it there before adding it?  

Sorry to ramble..I'd appreciate any help you can give!  Thanks!

Answer
Hello. It sounds like your previous fish did in fact have a disease although i am not sure if it was from bad water quality. Just to be i suggest starting all over. Do the fishless cycle with new water and test its levels every other day. Don't forget to add the appropriate chemicals. I use a chemical called Prime which can be found at many pets stores [if you get the big bottle refridgerate after opening it because it will go bad]. It helps level nitrates and nitrites and also chlorine and it helps the water stay clear.

When cleaning the tank you can you a fish vaccuum or bowls. Vaccuums can be found in almost any pet store. The vaccuum with get the stuff from the bottom and into a bucket and then you just dump the bucket. i suggest changeing 10% of the water. When using a bowl or cup etc. just scoop out the water simple as that. When adding new water you can use tap water but before putting it into the tank and the Prime or your chemicals of choice. If the decore has alge on it set it out in the sun to get rid of the alge then rinse it off. Be sure too wipe down the sides of the tank after you emptied it with a wet rag. The teperate of the water you put in should be around 70 or 73. so make sure when adding water put the faucet on cold. Is there anything else i can answer for you?
Corinna