[767Jockey]

Couldn't this be solved by putting valves in each return line to allow you to "trim" the return flow over the first few tankfulls? In other words, leave both return line valves fully opened. If you find that the left tank fills a bit more quickly than the right, you would just tweak the valve in the left tank closed just a hair. Over the first few tankfulls you could get this setting perfected, and after that point it really shouldn't change much, no? Just an idea.