Welcome to our forum.
I would not buy a spa from you, Because this is a leisure item and I will not take a day off work for you to make a profit
And BTW you signing "Terminator" at the end of every post you make is annoying.
Now that signature has an acronym to envy! Â
However, if you are selling spas, pools, and chemicals, the business should be open on Sunday’s.  Here is why:  you are going to have walk in traffic for chemicals and when a customer wants a chemical they will just go to the next closest dealer if you are closed.  I know many one store dealers that do well over $500K in pool/spa chemicals alone.  Of which usually about 50% is from weekend sales.  Would you take $125K in revenue off your plate from Sunday sales?  That is just on chemicals.  Assume if you sell 12 extra spas (One a month and a pretty small amount) in the year that is an extra $90K in revenue.  That is all $$$$ that you did not have before.  Looking for extra revenue?  It is as easy as opening on Sunday’s.