I used something like Armoral containing UV block and silicone. Bad decision on my part!!
Wearing flip-flops, I trod on the newly treated tube to enter the boat from my dock and my foot slipped off the tube and into the bottom of the boat, some 3 - 4 ft below the level of my dock. Left foot remained on the dock, right foot in bottom of boat. Outcome: badly bruised and scraped foot and a damaged cruciate ligament and much pain - which is still sore (8 weeks later).
I live on a fairly remote island in the Bahamas with minimal basic medical care (read: zero!) so must wait until I visit the UK in a few weeks to get my private medical insurance to sort me out.
Prior to the slip, I used some cleaning stuff I bought from a company in Florida, specially formulated for cleaning ribs, which was very good at cleaning the tubes (Zodiac 650 Pro Open - pvc - c. 2003).
As a last resort, the tubes can be re-painted if they look too discoloured.