Algae help pls.

I've recently gone through a depression streak and my fish have suffered through it. I haven't changed my water in about two weeks to a month so I know the ammonia level is probably off the charts. I had to leave to drive my friend a few hours away and will be gone all day but I did a 50% change before I left and noticed there was a weird Algae buildup that wasn't there before on my water filter spout. Is this bad/should I clean it? I also noticed one of my decorations is starting to get this rust looking pattern on it as well... any ideas?

They're just diatoms, it is a type of algae that is harmless, provided your tank is cycled you shouldn't have any issues with ammonia which usually triggers algae. How long are your lights on for? Cutting down the lighting duration should sort your algal issues. Failing that more frequent water changes and better water circulation.

I usually keep them on during the day then shut them off at night. Is that generally too frequently to have them on?

Get yourself a timer and set it for 4-6 hours a day - ideally when you're there to see them unless you have plants the lights are only really for your benefit. I'd never leave the lights on any longer than 8 hours or algae will be rife