Depends on the system. And my first question is what bulb?
Ozone is a means of sterilization, but it also will keep your water crystal clear by 'burning' off particulate that would normally be in the water column.
What you are doing is increasing the ORP (oxidation reduction potential). It's the natural ability of the body of water to break down organics (by oxidization). It's like rust on metal, oxygen breaking things down. ORP is a reading you can get in any water. By injecting ozone (in gas form) you'll increase that number, meaning the body of water will be able to clear more biological waste. Run 300mV or so and you'll have a hard time seeing the water it will be so clear.
The down side is anything above 450mV, and you're flirting with killing things over a period of time. At 600mV, you'll wipe the water clear of any living thing. You're fish (or whatever you have in the water) will actually dissolve. I use 600mV or more to sterilize incoming water we pull in from the ocean, then let the number drop naturally over night to below 400mV before using it in our ray touch pool. That way I know we've wiped out any parasites or unwanted things coming in.