Cheers!
Then you appreciate how hard it was to get this image
This was my second attempt and it's still not right; third attempt coming soon...
The sediment will settle, we took a trip down to sump 2, avoided going upstream, there was no one else in the cave, and I sat in the water motionless for five mins waiting for the sediment I stirred up to clear.
Next trip I want to try sitting on the down stream side of the sump as the sediment I stir up will wash away from me; but I'm not sure if this will be better as the caver in the image will stir things up quite badly approaching the sump; I'm hoping I can grab the shot before the sediment arrives.
I believe the scum only appears in 'sporting' conditions; only seen it once myself and I didn't dive the sump :-\