Live plants will help control the algae.Gotta get under 7 hours lighting per day and keep nitrates lower like sub 15.
Add a ton of floating plants, that will help too.
normal parameters: ammonia 0 nitrite 0 and nitrate under 40.
I have a LED light that I turn on in the morning around 7:00, and turn off sometime 10-12 at night.
How often and how much do you feed? Overfeeding will cause an excess of nutrients and may be contributing to your algae problem. Agree with all the above suggestions....shorter light period, more frequent water changes and a larger tank soon. Yes, Oscars will destroy plants but yours is still small enough he may not do too much damage to them right now. But bottom line you need to get a much larger tank very soon. Oscars are super fast growers, about an inch per month.
the symptoms you can see that tell you the water is Pee Soup, are rampant algae growth, 40 ppm nitrate (toxic) and depressed fish.
Hello; There are two ways multiple feedings a day can be a problem. One is the excess food laying around the tank left to rot. Oscars are messy fish. I have seen bits of food coming out of the gill covers of fish. The other is with feeding so often the fish have little incentive to seek out uneaten foodI feed about 2-4 times a day. I know that's pretty often, but I feed only a few pellets every time.
This is pretty simple, really. You have some of the most waste producing fish you could have-- in a way small tank-- with a lot of light. It's no wonder you have a lot of algae growth. In fact, along the lines of what dan518 said already, the algae is doing you a favor and absorbing and storing nutrients from waste (and uneaten food, if any). Physically removing algae basically removes some of this excess from the system, so that's not a bad thing, but the unbalance in the tank is a fact of life until you move the fish to a bigger tank, and ultimately you'd need a large tank if you're going to keep all these guys long term.
I understand it's temporary but that doesn't change the lopsided dynamics. If it was me I'd be feeding quite lightly until you get them in the bigger tank, more like just a few pellets a day total, rather than a few pellets a few times per day, fish can get by on less food for a longer period than some people realize. I also agree with doing plenty of water changes. You want to do what you can within the limits of the situation to balance things out better. Along those lines, if you're not attached to the common pleco, if it was me I'd trade it in-- they get big and produce a lot of waste, kind of counter-productive to the amount of algae they eat.