Richard J Kinch wrote: (clip) The ideal would be to have a bank of several
sizes of tanks with valves so that you can select an optimal aggregate tank
size for the tasks at hand. (clip)
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If the tank you have now is not unsafe, you can achieve the above goal by
adding a tank of either 10 gal or 40 gal capacity, with a couple of valves.
The former would give you a choice of 10 gal, 20 gal or 30 gal. The latter
would give you a choice of 20 gal, 40 gal or 60 gal.