water is looking greenish

[pandafishowner]

I set up my 29 gallon tank on Feb 20th. I originally had a 10 gallon. When I set up the tank, I used all 10 gallons from the original, and added about 10 gallons of new conditioned water. I had 6 guppies in my original 10 gallon tank. The day I set up the tank I had bought 1 cory cat. A few days later I grabbed 3 more cory cats. I waited til around the 1st to buy 4 cardinal tetras. Right now, my fish count is 6 guppies, 4 cory cats, 7 cardinals and a pleco I just bought. I had a pretty bad case of algae. I'm not sure why or how. Friday afternoon I did a complete cleaning in my tank. I took out all the decorations, all the rocks (the big gem looking ones, there isn't any gravel right now but was planning on getting the pebble looking stuff on my next payday) and washed it all down. I did about a 5-7 gallon water change hoping it would help my tank look not too green for water. I cleaned the inside walls with a glass cleaning sponge? I don't know how to describe it. It's a white sponge like thing, blue handle? Anyway, I was hoping that would make a difference. I added the half a capful of water conditioner to the water (it says one capful per 10 gallons). For awhile, my tank looked clear, but now it looks green again. I can take a picture if anyone wants to see it, it's much worse from the sides. I haven't been overfeeding either. I've been careful to only use about 10 floating fish pellets twice a day. I have algae wafers for the cories, but I only give one every other day as I was told. My pleco was automatically cleaning my tank as soon as he was aclimated and put into the tank.

Any idea what's wrong? I've been doing amonia tests every day, it says I have none. I did nitrate and nitrite tests today, none. Ph is around 7.2 which is within the ok range. The temp is around 76-78 degrees just like always.

Help?