I tried a dollar bill once, but no change.

Exactly what I use. I have a CT tank that I did about 5 years ago, through it on a shelf and let er' sat.
Still beautiful inside and out.

I love the sheer lack of physical effort needed with this method. Unfortunately, here in the UK there aren't many domestic appliances big enough to take a tank. However, I believe that some folks have used a cement mixer instead!

Thank you for the help!

Yep, I also have heard about people using a cement mixer. Probably a safer option in case of a leak. The wife probably wouldn't be very happy with dryer smelling like kerosene

Probably not a good idea putting flammable liquids in a dryer,
1) As mentioned above if you happen to spring a leak it will probably ruin the dryer and wife may or may not be happy depending if she wanted you to buy a new dryer anyway.

2) Flammable liquid not a good idea if you have a natural gas dryer with an open flame, that fuel tank can be like a tumbling bomb inside your dryer, even with a electric dryer it is a bad idea.

The dryer is merely an option. The important thing is the fish tank gravel and kerosene. I've personally not used the dryer method. I just spend time shaking and rolling. This method also works great for removing tank liners. It's pretty comon for people to put liner over rust instead of removing rust. The gravel and kerosene breaks the liner loose and it easily comes out in pieces.

I'm worried about Nemo going belly-up when you put the gravel back

Evaporust is quite gentle on the surface inside the tank. An excellent product with great results.
Phospharic acid is really good but you have to watch it as you can go to far. Thing is if you dry it off and don't rinse it with water the surface is resilient to rust . You can then leave it or treat it later.
You can also use electrolysis. Fill the tank with Bicarbonate and warm distilled water mix . Warm the water up in the kettle to the desired litreage of the tank . A good desert spoonful per litre mixed up in a bucket first. Fill the tank. Find a piece of mild steel ( coat hanger/call that an anode) that can be bent in a way as not to touch the inside of the tank at all. You will need an insulator ( a piece of wood) and pass your metal through a hole that you will make through the wood.
Suspend it in the tank. Get a battery charger. Connect live to the anode and earth to the body of the tank. You can clamp a pair of small mole grips to attach the earth lead to. The anode mustn't touch the inside of the tank. Good, now switch on and leave it for a day or two. Switch the charger off, remove the leads and the anode, empty the tank and rinse.
You won't believe the out come. It will need protection after that .
Ted.