White Film! Uv Sterlizer, will it help?

I have two discus in my tank that I have had for 3 weeks. I have been feeding a variety of foods recently and I have been making 30% water changes once every week. The ph is 6.0, the temperature is 80 degrees F. The ammonia, nitrite and nitrate levels are all fine also. Three days ago I bought frozen blood worms for my discus and the loved them. A day or 2 after feeding the bloodworms every morning for breakfast one of the discus appeared to have darkened and on one sid of him he has a white, decaying, filmy looking spot right by his fin. He keeps that fin closed most of the time. I also noticed his poo is clear and jelly like. he still eats, but he is not as active as he used to be. The other discus is fine. I am going to buy a UV sterilizer for my fish tank tommorow and i am hoping it will help, as I have had some people say that a UV cleared up these similar symptoms for their discus. Will the UV help? I also want to know if the UV will take blackwater extract out of my water and the yellow tannin it creates.
Thanks for the help!

a UV is a great way of prevention but if a fish has something in it's system it is going to need to be treated. I'm not sure what your fish has. I've heard of this before but have never experienced it. I would start by possibly putting a little metro on a peice of food and dangling it just above the water of that discus. when it eats it none of the metro will be washed off making it more effective. If it's internal then there is a good chance of that taking care of it.

I do have a thought outside of this however. If it is the only fish excreting jelly poo, it would probably be a sign that it's internal... however I've heard that the nymph is injected with coloring to make it look red. After digesting it would make sence to see no color or an unusual color.

Is it a brand name your buying? Where is the film at exactly?

Posting your Tank stats and a Photo would help diagnose what the problem is.

Marg.

Its by his fin and slightly behind it. I made a 25% water change and he seems to be doing better.

:? stay the coarse