Once week works for most folks.
You should make sure that its in a clean place but you should clean it every few days
You should clean it everyday that you use it.
You should clean your Clarinet every time you play in it.
You should clean it
you should really clean your horses stall from 3-6 days of the week.
Clean it.
When you have a spa used by the public you want to drain it often. The water in the spa should always be clear and clean.
Take a look at waterless car wash products. If you clean your car often, you could do it quite economically.
once a week.
daily
Once a month
You should clean it every 6 months or so to keep the reading lasers sharp.