Pioneer stainless steel fountain and slime

We have 4 cats and two fountains which I clean every other day... Including dismantle the pump. But by the second day and time to clean all the components have a slimey feel to the touch. The filter is also changed regularly.

So my question could this be bacterial or just cat saliva? The water level drops about an inch or two by that second day.

Any additive to use which might decrease this "stuff"?

It might be just cat saliva...hard to say.  Do all four cats drink from the fountains?  I only have one fountain, but only one cat uses it.  It gets slimy, but not in just one day..  If all three cats used it though, I imagine it wouldn't take long.

I WISH there was something to make it last longer between cleanings . 

Mine says you can use  diluted bleach to thoroughly cleanse it if you need to, so you could try that, but if it's saliva, don't think it will extend times between washings.  You know you can put them in the dishwasher, can't you.  Everything but the filter.  At least MOST of them are dishwasher safe