Evening all,I've bought a new to me dx milk tank and need to do as much install work as possible,what's the best way of setting the levels?

Is it just a case of spirit level on the top and adjust the legs?

Also it's got twin compressors and they seem to be huge,sticker on one is a copeland san2 v9 zr 12ME TWD,by my detective work these are 10hp each.

It's not a huge tank only 8400litres,would large compressors be for every day collection?

Cheers Scoff.