Question about brown "stuff" on glass ...

Lately I've been getting a LOT of brown algea/slime stuff on my front glass. I scrape it off and within the week it's back up there. Does anyone know how to get rid of this stuff?

I'm wondering if it has to so with the powerhead. I have one powerhead pointed toward the back of the tank and there's hardly any "stuff" near that part of the front glass ... however, the other powerhead is pointed toward the front of the tank and the brown "stuff" is all over the area where that powerhead is aimed. Maybe I'll try moving that powerhead and see if it makes a difference. I wouldn't care if this "stuff" was all over the back glass, I'd just like to be able to SEE my fishies!

Well, the power head was pretty much forcing the water right at that part of the tank pretty hard and it was still growing there, so that wasn't the problem. I have moved the power head to blow side to side instead of to the front, so we'll see if that helps.

The tank is 20 months old. The only new thing I've added was a Lionfish a couple weeks ago but the "Stuff" had been showing up before he came along. I will try to feed less but I already only feed twice a day ... a couple krill and a pinch of Marine pellets in the am and if I think of it or if the Lion seems hungry I feed krill or squid again in the pm. I remove anything not eaten in about an hour or so.

I have cleaned the front glass and will do a couple water changes over the next couple weeks and see if that doesn't help. Thanks