water effects advice

[Sinistermind]

so im currently building a snow wilderness display board for my alien themed tyranids who have snow style bases, I'm including water effects and a waterfall, ive gotten the waterfall down but as far as the running/standing water i cant exactly decide how to tint/color it, i know you paint the underlying foam and you can also mix ink into the water effects while its still liquid but i want to acheive a look similar to these



im thinking maybe a black mixed with either dark brown or dark green to paint on the foam underneath and maybe a little dark(black?/brown?) ink mixed in with the liquid water effects before setting.

any advice?