Thanks, all, for the additional ideas. Have to try much higher translucence values in the lambert. For this render it was at 1.8.
And , yes , the model, made in Xenodream, is convoluted and ragged to begin with.
Should try some simpler model, the current one is 66 meg file size , Poseray shows it at 900,000 faces and I did not smooth it except initially in Xenodream.
The water shader does get very slow on even the one planet object, let alone the imports.