How many lumens does a standard 1000w hps light give off on average
An easy way to find this out is by looking at HPS bulbs online.
Most of the 1000watt bulbs I've seen emit anywhere from 130,000 to 140,000 lumens. This number should be about the amount of lumens leaving the bulb. The amount of lumens hitting plants however decreases with distance, and that goes for heat too. So dialing in for light could be nearly as important as dialing in for heat is.
When you have big system like a 1000watt HPS you should pony up and buy a light meter too, just to make sure everything is fine and you're investment isn't being misused or wasted.