Your original sentence has an informal feel to it.
A more formal way of saying that could be "It must be cleaned periodically. I recommend doing so every third time it's used."
(I like the informal version better.)
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.
I like the original sentence too. Problem solve, the guy in Youtube seems to be correct. Thanks again.