"broken" fins, lethargic dempsey, plus more. HELP
 

Hi
My dempsey looks sort-of lethargic this morning. Hes kinda hanging out on the bottom. He appears to be breathing ok. His fins look ok.

2 of my 4 severums gave what appears to be broken fins, a part of the fin. I also noticed this morning one of the severums have a white growth on one of his fins. Probably the size of a pen tip.

My parrot is jumpy.

I just finished a water change. PH was 7.2 Nitrite was 0. Ammonia was 0. Nitrate was 40. Ive had long standing prob with Nitrate, I have a hard time getting it under 10.

I also added a large piece of driftwood a few months ago. Ive noticed over time the water gets a color tinge to it. But levels are usually fine. I assumed the driftwood was staining the water along with my other pieces in the tank. I changed position of the driftwood during water change this AM, and noticed, what looks like fungus, on the the underside. About the size of a lima bean. Is this driftwood causing me more problems? I have a large piece of coral as well, I thought the 2 would balance each other out.

So the question is... I know there is something going on with the fish, but what? Is it fungus? FIn rot? And the driftwood, do I keep it?

Do I treat, and with what?

Please, any expertise or advise is greatly appreciated. I get much better advice here, than at my local pet store.