Most local fish stores (LFS) should test your water for free and sell you the chemicals you need to get it back to the right levels (I know for Saltwater my LFS requires you to bring in a water sample before they will even sell you a fish)....
-DO NOT ADD LIGHTS RIGHT NOW!!!! the lights will cause you to get even more alge.... also how close is your tank to a window & how much sunlight does it get? Light causes Alge to grow! ....
-Have you considered getting snails? they can help keep the alge down as well as the pleco....
-How often are you doing water changes?
-Do you have a filtration system?
-Are your plants synthetic or real? real plants can casue alge problems and this could be the culprit (I never keep real plants in a freshwater aquarium for this reason).
Overfeeding fish can be deadly to them and is very dangerous.... stick to feeding them at certain times of the day only and tell everyone in your house that they are only to be fed at say 9 am and 6pm ... maybe having only 1 person responsible for feeding the fish is the best idea. With the feeding system you currently have set up:
i think my fish are being fed way to much- bc anyone that passes by the tank, always throws them something to eat!
this plan is a sure set up for tank falures: including dirty stinky water, dead fish, alge blooms etc.
Perhaps going to the library and finding some books on keeping the particular fish that you have would be a good idea along with a book on basic aquarium care. Have EVERYONE in the house read them.
In your case you need to go to a LFS today and fully explain your situiation... bring in a water sample and ask them what you should do.... I think it will include water changes over the next few days and possibly adding some chemicals...
If you have fresh water fish they need a little salt too. I don't know if you know that, but for those of you that don't...the salt helps them stay calm and healthy. Here's what I use API aquarium salt. It is a natural fish toxin which improves the gills function and promotes disease recovery too. You only put one tablespoon for each 5 gallon. And remember salt water does not filter out so you only replace the salt you took out. Well that's just a little tipper.
Do not do this without talking to a knowledgable fish person at your LFS first and telling them exactly what your set up is with what fish you have ... certain fish can handle the salt and others wont do so well (ie:will die)... I sucessfully had an angel fish that lived for about 10 years and NEVER put salt in the tank (I have never had to use salt in my freshwater tanks ever and have sucessfuly kept freshwater aquariums without disease, becasue I quarintine before adding new fish into my system and only buy from a reputable source).... salt in freshwater tanks is usually used for healing purposes and not on a regular basis unless you have fish that could be a borderline brackish fish (there are only a few species that go both ways).