Finally bought a battery hydrometer, need help with results

You might have stratification, where the watery part is on top giving low readings. The high acid at the bottom eats the bottom of the plates-not good) Try to keep the mix even.

With the caps on, tip the battery up on its end and leave it for five minutes, then tip it up on the other end and wait five minutes, then when it is upright, wobble it back and forth some. Now take the SGs again.

To prevent stratification while on Float, you need to give the battery a shot of higher voltage every so often.