What is the right length for a pool vacuum hose?

In regards to comfort and safety while swimming, yes a hose can be too long. Also, the hose might also be able to tangle and/or not allow the cleaner to move correctly and to its full reach. Lastly, The suction power needed for a longer hose would be greater; to measure suction the vacuum might have come with a neat gadget that reads this and tells you the optimal level of suction. Hope this helps! :)