First off, the pleco needs to be removed from the tank. You say it's a "big pleco", I'm assuming a common. They will cause havoc on your tank and need a much larger tank than a 10 gal
. They will get huge and are big waste producers.
Stop using the water clearing chemical. 9 times out of 10 it will just cause your tank to become even more cloudy. I used that stuff SO much in my 10 gal
before I started coming to this site and it never helped. Eventually I had to tare down the tank and start over. What are your exact water test results? Are you using strips or a Master Test Kit?
It could be a bacterial bloom, among other things. How long has the tank been set up? If it is a bacterial bloom, you may want to do the blackout method. Which basically you completly shut off the tank from any light source (including sunlight) and don't feed the fish or even peek inside for 5 days. I believe this is how you do it. I've never done it before but have read many members on this site talk about it. Maybe someone else could chime in on how they did it.
Also, you said that the Buenos Aires is a Cichlid, are you sure? I just checked www.liveaquaria.com
and it lists it as a Tetra.