Your project is very interesting.
I am myself a surfer and i think that foam shaping solution could be used for cheap floating housing (instead of float buoys). I will investigate and get back to you.
Did you get any feedback regarding the turbidity sensor and ph accuracy compare to traditional costly solution? I cannot find any spec on accuracy on the datashet.
How did you manage to setup a waterproof connectors for that turbidity sensor? It seems to be critical. Looking at the turbidity sensor pitchure i cannot figure out how you can avoid corrosion on the visible connectors.