After cleaning it I would coat with a tank sealer. I did it with mine and it hasn't rusted yet. The only thing that I would caution is the reaction between the sealer and any residual acid. I don't how resistant it would be against that and if it flakes of it can cause problems.
Also I found a container of this stuff in are basement always wondered what it was used for this stuff claims it can etch concrete. Sounds fun.
