Mattress Protector Recomendations

General Discussion

I have just purchased new mattresses for my HMO and want to protect them against spills, bugs etc.  I quite fancied the protectors that fully encapsulate the mattress and on looking found a huge variety with a vast price range.  I wondering if anyone uses any of these in their properties that they found to be effective, non noisy and does what it says on the tin, without costing a fortune.  I heard that some landlords change their mattresss every year/between tenancies, not something I was planning on doing if the matresses and decent quality and clean.