equipment

Hey guys (and gals) I just bought the Arcadia IP64 controller for my uv tube light and it has a grey circular switch on it that flickers red when I turn it on. Only for a few seconds. I have no clue what it does and the instructions dont say anything about it. I've googled the hell out of it...

By the time you factor in heating devices, thermostats, light fixtures, light bulbs to go in the fixtures, even stands to hold light fixtures... That's a lot of boxes. Even more if you have an aquatic or semi aquatic setup... Water filters, pumps, aeration, submerged heaters, UV sterilizers, UVB...