I guess it's down to what rendering price you will pay for the effect you are looking for.
In your example tgd the transparency is set at 2.0 . In my understanding 1.0 would be full transparency for simulating water. If that is the case using a value of 2 is a not a real world water setting. Of course you can enter any number you want, but the way I look at it, if you use non real world settings you can expect to deal with non real world effects.
From such a camera height maybe colored water with a lower transparency would still give you something acceptable as well as rendering faster. Same with decay distance. 600 meters may be beyond any real life ocean. NOAA says almost all light is absorbed in the first 200 meters of the ocean.