Betta died from unknown infection what do I do to make the tank safe

ok, so I have a ten-gallon plated betta tank and I moved my betta to a twenty-gallon last week. about three days after that he just stopped eating I thought it was just stress from the move and the high amount of surface agitation from the sponge filter so I moved him back to the ten-gallon. then I noticed that his fins were fraying and that there was some white stuff growing at the base of his tail. I thought it was just fin rot or an external parasite so I was just gonna get some general cure and fin rot meds but the next day he died. At that point, he had not eaten for four days and when I scooped him out of the tank he had white fluffy stuff on him but not in his mouth just on the fins and body. I think it was fungal but have no clue how it got to him as he hasn't had any tank mates besides two nerite snails for about a month. My problem now is how do I make my tanks safe for new fish in the future. I will most likely take down the ten-gallon as im, not too pleased on how it looks but I don't want to dismantle the twenty-gallon. How do I make it safe for new fish? p.s I have no other fish only the two nerites I also don't have pictures of him while he was sick.

 

Well, you'll probably want to sanitize each tank, as he was in one before the sickness occurred and in the other when he passed on, it's best to sanitize both to be safe.

You now have two options really... 1. Boil all the decorations and gravel (Not sure how this may affect them if they are painted.) or 2. Throw all decorations and gravel out. For your live plants, you'll have to throw those out if you want to keep any new fish safe, you could spray them down with peroxide but it doesn't work for certain plants, if you throw all the decorations and plants, out you'll need to get new ones and escape the tank.

Now for the filter and tank itself, drain the whole tank and relocate the snails, fill the tank up and pour in a bottle of 3% Hydrogen Peroxide, the big bottles work best. after that let the filter run for a few days so all that peroxide gets through the filter (It'll evaporate though). If your tank is already cycled, all the beneficial bacteria will die and you will have to cycle the tank again.

For the heater, if you have one, just let in soak in peroxide (Don't have it on though, it's not needed).

It may also help to replace the airline tubing.

After that, drain the tank, rinse it out by filling it with fresh, not-conditioned water a couple of times and just wipe it down along with the heater and the rest of the filter inside.

Then just set the tank up again as if it were new.

These are just simple and basic instructions but always do what you feel is right.

 

welp looks like I got some work ahead of me thanks for the advice ill start taking apart the ten-gallon now as I was gonna do it anyways.

 

I soak everything in a 10 to 1 solution of bleach and water.

 

what do I do with the nerites is it possible that they are carrying something or can I just give them to a friend