I have that pool scene that I did a while back and the client wants a night time shot. Do I just delete the sun or turn it off? What kinda of lights do I use for the lamp lights…Vray Dome? Plane? etc. Why is the sky blue and why does it shrink when it’s cold…These are some of the many questions I have today.. 
If you delete the Sun the Earth will freeze.
Think of it 
yes and much shrinkage will occur. Think about it.
You could try the VRayMoon from the SDK…
And I guess the other question…If a tree falls in the woods and there is no one around to hear it, does my shrinkage make a sound
VrayMoon..Are you joking…LOL… Or have I missed that joke completely…
I think he said about VrayUniverse. The last time I used it - I recreated a BlackHole. Pretty nice. LWF was usefull addition + vrayedgetex + caustics
your getting there lol. sorry i couldnt comment i was laughing to hard 1!!!1 omg you guys cracked me up with this one specially the google!
ROFL !!!
brrr…that pool looks cold. Much shrinkage going on methinks.
significant shrinkage!
:lol:
its also funny that nobody seems to have posted a helpful reply 
I would but i dont have much experience at these types of scenes. IMHO though, I would say that you are on the right track regarding having some light in the scene instead of deleting the sun. If this is getting towards evening i would say that normally there would be a bit of colour in the sky on the horizon as the sun goes down making the image a bit warmer. If it is later than this, I think in photography with a long exposure will start to look like more of a dark blue on the horizon fading to black (could be completely wrong but you know what im getting at). If you cant get it looking good you could always go back to the old manual way of doing it by referencing photo’s from the time that you are looking for.
BTW, you would want to hope that the pool is heated!
lol your right no one did really answer his questions i seem to always use vray sun and sky for these night shots. i bring the sun below the horizon and the vraysky in the enviroment slot seems to give me a decent amount of minimal light. However it give you a sunset look. Otherwise i would you use a night time hdri.
evermotion has some free dark ones which can give you that minimal light your looking for maybe. Hope it helps.
Here is an update. I did take the sun below the horizon and added some lights IN the pool. But the render times are 52:08. I think the lights under the water took it from 5 min to 50. Oh…And no problem on the question gone unanswered…LOL…I did open up that can. Pool is heated and try no to zoom in on speedo guy…He is starting to get a complex.
your not getting enough skylight. And whats with the colored lights in the pool? Just make them white or slight warm tint.
just put some hot chicks in there and you dont have to worry about shrinkage anymore…
oups, did i really say this
Maybe throw in a dim direct light for some moonlight. I think a simple way would be to have a VraySun high in the sky but a lower the multiplier and instead of using VraySky just use a spherical environment gradient map set to the colors you want for reflections and GI. you may want to use two separate maps so you can desaturate the GI.
I know this is an oldish post, but what happens when you want to do a timelapse scene (from nigh time, through daytime and then back to night time). Can you simply not just use a daylight system and animate the time for the sun. Will the sun (when below the horizon) go to darkness, or is this something extra you have to animate/tweak yourself to get it looking right, as Eric has to do in this scene ?