Your return might be making your OF work a little overtime. You can try adjusting the water flow of the OF and see if that brings down the water level. To slow the speed of the return, bypass valve is necessary.
The level at the slits of the OF depends on you. The higher the OF, the higher the water level, etc. The speed at which the OF sucks in the water to the filter depends on the speed of your return pump.
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30g reef tank, CPR CY192 filter w/ DIY plumb running Rio 17HF return, Coralife 3x 9w UV Sterilizer, 3 24W T5-Helios 10K Daylights/3 24W T5-Helios Blue lights, 2 Logysis blue meteor light strobes (moonlights/24 Blue LEDs).
Tiger tail cuke, asst. snails/hermits, asst. feathers, rainbow acan,zoos,shrooms,bubble,galaxea, asst. shrimp, 2 ocellaris,mandarin,zebrasoma xanthurum,pink-spot watchman,red-striped pistol. | 
Is this pushing it too much? 
Now I'm wondering if I'm pushing the limits of the overflow a bit. The water comes right up to the top of the slits in the overflows. Is this where it should be? Should it be a little lower to allow for some buildup of algae etc.? I've never done anything quite like this before, it makes me nervous. 
jb
