K&HPet Products Thermo-Water Bolster Heated Orthopedic Dog Bed Gray Small 17 X 20 Inches

How do you keep the water clean? Will it start to smell? It says to use grapefruit seed extract, but is there anything else?

So there is a bladder that u can fill with cold pr hot water? If, not please explain in more detail how exactly the bed cools and warms.