So you're looking at hot tubs for sale. You should know that any time you leave water sitting around, not circulating, you're asking for bacterial overgrowth. Caring for a hot tub properly is very important if you don't want that to happen. If you DO want that to happen (you mad scientist, you!), your job is easier, and, some would argue, more interesting. Here's how to neglect your hot tub properly, so you can grow your own unregulated biology lab.
First, what can you expect to grow in your hot tub?
The answer to this question depends largely on who uses it and how often. The human body is covered in millions of microbes, ranging from E. coli strains of bacteria, to wild yeast strains, and even exotic bacteria normally found only in the soil in certain regions of Japan. The more often you and your friends take a dip, the more bacteria you are introducing to the water. After you've sufficiently cultured your hot tub, follow these steps to see what diabolical things you can create in your very own back yard.
Step One: Keep the Water Still and Warm
The first rules of keeping bacteria from overtaking your hot tub is to move the water around once in a while, and allow the tub to cool before you cover it. Most hot tub manufacturers recommend turning the jets on for a few minutes once or twice a week and leaving the pump running the whole time it has water in it. This breaks up bacterial colonies and keeps them from growing.
Instead, leave the jets off, don't drain the tub, and keep the temperature high. Bacteria flourishes at temperatures close to 100 degrees, so aim for that zone.
Step Two: Don't Monitor Your Tub's pH
The typical recommendation is for your hot tub to maintain a slightly alkaline pH level of about 7.4 to 7.8. This keeps bacteria in check, because those little organisms prefer neutral to slightly acidic conditions. You're going for a smelly primordial soup of biological processes, though, so ignore the pH level entirely, the bacteria will create their own ideal environment.
Step Three: Neglect to Add Chlorine
In its most common natural state, chlorine is a deadly gas. For use in pools and spas, though, it comes in powder or tablet form. It dissolves into the water and kills off little organisms trying to make a home there. Obviously, you have no use for chlorine in your hot tub, since you're attempting to either cure or create some terrible disease a la the discovery of Penicillin.
Step Four: Feed your Bacteria
Despite their tiny size, bacteria are voracious consumers of all things delicious. Skin cells can only sustain them for so long. You're going to have to drop some food in there. Many hot tub owners do this accidentally when they throw a party and feed their guests in the hot tub. You can skip the guests (they're liable to call the CDC on you anyway), and plop food right into the tub.
Step Five: Keep the Cover Loose
A tight fitting cover robs your experiment of vital gas exchange. An anaerobic environment (water without access to oxygen) will suffocate your bacteria. Make sure to leave the spa cover loose, but keep the tub at least partially covered at all times, because bacteria can be destroyed by sunlight. This will make your tub harder to heat, because some of the heat will escape through the loose cover, but isn't that a small price to pay for fame... or infamy?
A hot tub can be a relaxing, enjoyable way to spend an evening, or it can be a mad scientist's best friend. Whichever direction you choose to take it, make sure you're having fun with it!