Hm, everything said makes complete sense, but it was a common pleco, well they both have been in fact.
I do weekly water changes, gravel vacuum, glass cleaning, etc.. and do treat the water before adding it to the tank with Prime and pH 7.0 and test it before adding to the 10G tank.
The other fish are by no means bullies. The Red-tailed Shark is still a baby and he is a little scrappy by himself but he doesn't ever pick on the white-skirt tetra's or my male/female betta's.
I know the 10G is small for a larger Pleco, but I also have a 46G for when it would get about 3" and when the red-tail grows up a bit. Also, I'm getting a 125G for my Oscar's in the spring and eventually I would love a large Pleco to go in there.
onefish2fish - the tank did cycle for about a month. I watched closely as the process ran it's course and did necessary water changes, then when everything was perfect I added the 3 white-skirts and they've been doing great since the beginning.
This is the tank, BTW the Comet's were removed asap and placed in a different tank, now it's just the fish listed in my first post.
I really appreciate the feedback though :)