When it comes to cleaning we suggest looking at your tags and seeing what the manufacture recommends. If your tag is unreadable or missing we suggest contacting the manufacture. If for some reason this cannot be done the general rule on cleaning mattresses is only use a vacuum.
Anything that can create moisture in your mattress or could stain it can void your warranty. Cleaning chemicals can potentially saturate the mattress creating mold and mildew. Using a mattress protector with sheets makes it so spills and dust cannot get down to the mattress itself, this makes spot cleaning unnecessary since they can be removed and laundered.
Even when using both of these products once a year it is still a good idea just to take a vacuum to the mattress itself. If you have allergies you may consider doing this more often to ensure there are as few allergens in your bedroom as possible.