Algae in hose

I'm on my 2nd Camco Blue colored drinking hose this year for the connection between the outside faucet and my On-the-Go water softener along with the 3rd white drinking water hose between the water softener and the house/RV. Algae only appears in the white hose. I install a new washer with the screen on on all ends of the hoses after I clean new hoses out with Bleach before I attach them to anything. I'm wondering if warm water from the hose sitting in the direct sun might be causing some if not all of the algae problem. Like I stated earlier, I did have the complete hose enclosed in the black rubber water pipe insulation and all but the last 4 foot of the white hose from the softener to the house connection under the RV and out of the sun. I'm thinking of getting either 3-4 inch PVC pipe, Rhino hose or even the silver AC/Heater/Dryer vent type hose and run the water hose through them as a sun shield. None of my neighbors use filters or cover their water hoses and none of them get algae in their hoses. If I had enough hair on the top of my head, I'd be pulling it all out.