From what I’ve been told nerite snails are amazing algae eaters. I may have misread your post, so I apologize if I’m wrong, but common Plecos get huge. They can easily grow between 6-12in. If your tank is small, you may want to consider returning or rehoming it.
Thank you for the snail advice. I know that common plecos get massive. He is just a few months old, so still relatively small. I have him in a 30 gallon tank right now, so he is quite comfortable. I am still fairly new to the "fish business" so as I get more experience, I will be getting larger tanks! I will make sure this coincides with my pleco's growth to ensure he gets the habitat he deserves. Thanks!
Ok I’m glad you’re planning ahead for it. Two other tidbits you may already know about them 1) they produce a good bit of waste and 2) they’re terrible algae eaters.
General advice for algae is to reduce your lights to 8 hours or less a day, make sure your ammonia/nitrite/nitrate levels are as low as possible.
How old is the tank?
Brown algae is often diatoms, they are common in new tanks 1-3 months old and generally go away on their own eventually. You are the best cleaner for this stuff, you can just rub it gently off plants and decorations. Adding a nerite snail would be great, it'd help with algae and wouldn't breed in the tank, most other snails can breed out of control and over run your tank.
The size of common plecos listed above is very conservative, I've seen ones between 18-24 inches in large tanks. You'll eventually need a tank at least 100+ gallons to accommodate it. Don't wait until the pleco looks too big before upgrading, you'll stunt the growth of the fish causing deformities, pain and a premature death.
Try a Japanese trap door snail. They do great with algae and excess fish food and are live bearers so you don't get overrun with baby snails.
The best algae controller is you.
Scrape all algae off of the walls with a scrubber pad.
Reduce light period to 8 hours and do it in blocks(4 hours on, 2 hours off, 4 hours on, off for rest of day).
Feed a little less for less nutrients in the water column.
Do more WCs or larger WCs to remove any extra nutrients that can build up.