Making outdoor wooden steps slip-proof

I've got a few steps outdoors leading to my basement and I have been looking for a way to make them properly slip-proof.

Being in BC, it rains constantly and algae growth is a nightmare to constantly deal with. I have constantly been replacing the slip tape on the stairs as they seem to only stick for a few months before peeling off because of weathering and the daily traffic.

Is there some sort of rubber coating I can apply to make maintenance easier? Even with pressure washing the stairs are still a bit green (though are not really slippery anymore). I've thought about mixing some sand with paint but don't really know what will work and what will not.