This is on my RD350LC, the tank is in a very bad state so I thought I’d try the Electrolysis method.
Some bright spark has filled the tank with liner in the past that over the years has broken up into hundreds of parts. I removed the fuel tap and blanked the hole off, then spent hours hosing out the tank with water and probably got about 90% of the liner out.
Filled the tank to the brim with water and a 3/4 of a small pot of baking soda, battery charger negative to the tank and an old cleanish Allen key in the water connected to positive.
It’s bubbling away at the moment and a hell of a lot of rust is coming out, either bubbling to the top or sticking to the Allen key which I clean every hour or so.
Only thing to be careful of is that hydrogen gas is produced so must be done outside and to keep the tank topped up with water and agitate tank now and then.