After 8, 10hr sessions of electrolysis, changing electrolyte and anode regularly, I was still pulling out the same amount of debris and wondering if I'd have any tank left to seal.
So in went POR15 - last half of degreaser, rinse, force dry with heat gun. Then Metal Prep etching solution for the specified 20mins, swilling it around continually. Then rinse and force dry, before getting the sealer in, rolling it around and draining off for specified 10mins, during which time I prepped and applied the exterior patch where the pinhole leak had been, just for good measure.
Even though the specification is 96hours curing time, I think I'll wait a couple of weeks, just in case any sealant pooled anywhere - I'm sure it'll take me at least that long to fibreglass the seat pan, so the tank needs to be on it's mounts for that anyway.
Wish me luck (as you wave me goodbye!)