Different parts of my tank get hit by sunlight at different times of the year. The only thing I notice is that my corals look all washed out (AKA, how corals look naturally in the ocean) when sun is hitting them directly. Otherwise I find it's a nice time to look at the tank. It's always near sunset and as the light moves across the tank it makes for a really interesting way to see it. Areas that are normally in shadow get lit up, you see detail that you otherwise don't, the fish look really beautiful in natural sunlight... etc etc.
So long as it doesn't cause heat issues I don't really think it's that big of a deal. If you're going to get algae, you're going to get algae. IME sunlight hitting your tank isn't going to be the straw that breaks the camel's back, light is only one ingredient in the recipe for algae and if you're growing corals you've certainly got enough artificial light to do the job.
|