Run the pump 24/7.

I do not have a UV light on my pond so I canÂt help you with that.

Fish need the filtration and the oxygen from the pump running to breath. Oxygen levels are lowered dramatically when the pump is off.

It is nice to be able to breath.

Good luck with your fish and pond!

Jason

If the water does not have sufficient oxygen it will get stinky even if there are no fish. You don't mention any filters, do you have a filter system? You should run the pump and filters 24/7. Check the filter material once in a while. You may be surprised how much stuff accumulates.
The UV light kills algae and certain bacteria. It should run 24/7 as well but there is a thing called dwell time. The algae must be exposed to the light for a long time to get enough UV light to kill it. That means the water flow through the unit should have a long dwell time (should be very slow). You can either get a small pump for dedicated water flow or you can use a diverter from the regular pump line going to the UV unit. If it does not seem that the algae is getting less, then the water flow time should be reduced further. Do not look directly at the light. It can damage your eyes.
Things you (and we) need to know are how many gallons of water, how much surface area, size of the pump, if you have a waterfall how high is it, is the pump submersible or out of the water, what kind of filter system do you have, how deep is the pond and I am sure there are other thing that are slipping my mind right now. If you are not sure of some of these things especially sizes and volumes, someone here can help. Just ask. Sandy
Oh! Do you have rocks on the bottom or plant shelves?