Tommie, sorry about the gallons of water to change, I was thinking it was in a 6 gallon, do a 5 gallon water change this morning on your 55 and see what happens.
It is amazing how fast an animal responds to new salt water.
Something I have found, and it may be just me is, when I do a water change, I always have the new water semi cool.
It seems to make them respond in a happy way for lack of a better way to put it.
They like the change in temp for a short time.
Not to cool tho, maybe around 72 to 75 is about what my water is when I do a water change.
I also, when doing top offs add cool water.
Seems to be a stimulant for them.
I know allot of people insist on having the same temp for water changes and top offs but I have never done that.
It's a wow thing for the inhabitants and they come to where I am pouring it in to take a cool bath it seems.
Just my opinion tho so take that info as you will.