How to safely upgrade a tank?

[SharpieItBlack]

I'm moving from a 10g to a 20g.

My question is how to safely do this?

I have a few things I'd like to say about what I plan to do and want to know if they're ok.
I'm setting up a 20g in my living room where my old tv used to be, on a sturdy wood stand.
Is it ok to use a filter built for 40gallons on a 20 gallon tank? I've heard mixed feelings on using a filter bigger than your tank size.

Second, as I'm setting up my new tank can I use my old decorations and old gravel? I will be cleaning and washing them off before placing in the new tank. And will also buy more gravel.

How long after fully setting up the new bigger tank should I transfer my fish, I heard 24 hours. Is that enough time?
And when I go to transfer my fish, what's the best least harmful way to do that? I'm moving him from my bedroom to the living room (about 20ft if that matters). I read somewhere to fill a bowl with water and put it in the old tank, and use the net to ease the fish into the bowl and slowly ease him into the new tank.

 

[abrinn23]

Using a filter recommended for a bigger tank is never a bad thing! Over filtration is actually really helpful. And about the decorations if I were you I wouldn't even wash them I would just take a gravel vacuum and clean it that way while it is still in the old tank then transfer it over to the new tank.

 

[SharpieItBlack]

The only reason I wanna wash them is to scrub off any existing algae, my 10g has some in it but not much. I try to scrub out all the algae when I do my weekly change. And what should I do with my old tank then? The filter is kinda crappy, but could I scrub and clean it out and use it for another animal? Like a frog or something

 

[abrinn23]

Ah okay I understand. If I were you I would scrub them with dechlorinated water and keep them wet so you don't lose your beneficial bacteria. You should also take the filter pad out of your old filter and stick it in the new one because it could instantly cycle your tank. And for your old ten gallon you could always do a red cherry shrimp tank