To me, it's fine. I don't know about others.
Just... try to avoid using "have to" in any sentence. Otherwise it can come across as rude, even if it really isn't. Replace "have to" with "I recommend" or "you should" and back it up with facts (not just your own experience, I mean FACTS)
Example: "You HAVE to clean that bowl 2-3 times a week."
"I recommend cleaning that bowl 2-3 times a week, because of it's size. Ammonia builds up pretty fast in a smaller space, and ammonia is deadly and painful to fish - it causes ammonia burns, poisoning, rot, and possibly death."