How do I properly sterilize my tank after unknown deaths.

[BellasMomma]

Long story short.... Got a betta to add to my divided 10 gal tank. He died from what I was told was ick. Now my female died this morning from what I thought was a parasite. Now I'm left with my guy. The tank has been treated with ick guard and parasite guard... The tetra brand. If there is ANY hope for Baltar's survival then I need to get this tank cleaned right.

Questions:
bleach- i've heard I can use this but how!?
sponges- any new sponge or one made for tanks?
I have sand. Do I need to buy new sand or is there a way to actually get it clean?
decorations- all fake plants (with the exception of a marino moss ball) can I use bleach on my decorations?
my moss ball, do I need to toss it or is it safe? Its been out since the ick treatment (first one)
filter- boi wheel penguin 100.... New cartridge right? Clean filter with bleach too?
Cycling the tank.... I need to do this right.... Since it will be a new filter cartridge.... 2-4 weeks just like a new tank?

Now for Baltar.... Do I treat him for anything?? Or just see if there are any symptoms? So far he just hasn't ate today, but it think that's from being moved outta the tank. He has been through both treatments....

Thank you to all who can answer some or all of my questions.

R.I.P. My Violet - my first betta
R.I.P. Spur - The one I was hoping to give a better life...

[Sena Hansler]

I'd use a scrubby/sponge made for tanks because kitchen sponges hav chemicals.
I use vinegar... milder than bleach (I'm allergic to bleach)... which is equal amounts of water and vinegar. Not sure of the bleach.
I am also unsure of sand, but it may be the same thing as gravel, where you can put it in hot hot water, rinsing it thoroughly, etc.
For some decrations there are crevices. however you can use bleach just use extra care to thoroughly rinse the heck out of them.
Live plants, quarantine in a bucket or container, for 2 weeks with tap water (minimal to no water conditioner added).
Cycling usually takes 4-6 weeks, adding a pinch of flakes or pellets as the substance of ammonia (rotting food). This will get it started.

I do not treat any betta who does not show signs of anything, so best to hold off any treatments - just clean warm water

and sorry to hear you lost your bettas :(

[BellasMomma]

thanks a bunch! I would definitely prefer to use vinegar over bleach so thanks for that helpful tip.

[Sena Hansler]

I am dangerously allergic to many chemicals including bleach so I compromise :p Jts remember the rinse the heck out of it after lol