Swimming pool with caustics

[Crayox13]

Hi,
I'm having problem creating good caustics on the bottom of the pool. I created a "no thickness" object, so only 2 dimensional object for the water. First I outlined the edges with a line, closed the line, added edit mesh only so it becomes a solid, and then I added some noise, tesselate etc. When I rendered, some caustics DID go through but I had a lot of splotches - errors on the water. I guessed it's because it's a 2 dimensional object (like a plane). So I added a shell modifier to it all. All splotches are not gone but there is no caustics, nothing goes through. Why?

What kind of object should be used for water to have caustics?

Thanks

Edit:
It seamed the rest of the water object was too flat so caustics didn't refract correctly I guess, I now added small noise to whole object so it seams better now. Still testing, and would still like some input about this. It's an exterior scene btw.

Edit:
Found another problem. Values of 5.0 and even smaller 2.0 for search distance were so tiny that I got only invisible caustics pixels, now I tried, just accidentally, a value of 10 and found where my casutics was hidden all this time. Maybe this will also help someone

[Crayox13]

Another problem...I have grass around my swimming pool, it's vrayfur, the generator is excluded so it doesn't generate caustics, nor receive it, but still when I use it my photons take ages to calculate. Without it, they take like 20 secs. How can I make vray ignore vrayfur for caustics?