Hey Jim you are the bomb! Not only is this a good place for spray bottles, I also found a shut offf float valve just like the one in my fresh water tank for $22. been haphazardly looking for a few months for it.
On the round tanks ..don't waste to much time and money replacing the float with the ball type.... It will just snap off again.....go with this style and it will serve you better....
more ridged and they come in the 3/4 inch inlet...so you can hook it up on the cap on top of the tank.......