If there is still a white ick spot on my fish tail after treatment,
 

does that mean the treatment wasn't effective or is it just left over from before?

What ick treatment did you use? I am thinking you have said Quick Cure?
How long did you stick with the treatment? Does the spot appear shinny, or does it look like possible scar tissue from the ick?

Hi Tmom, Yes I used quickcure. I did it twice, as directed. Took out the carbon filter. Put it in for 3 day. Still saw it on the fish, so I did a 1/4 water change and did it for 3 more days. Now I can only see it on one fish and it's not as much as it was. I can't really tell if it shiny or what, as it is smaller. It just kind of looks like left over ick from before.

You keep on treating until the ich has disappeared from all of your fish for at least 3 days. If you do not have an effective ich medication, remover it with a big water change and use a salt and temperature treatment. I have never seen that one fail. It is described in detail here The Skeptical Aquarist along with a good description of the parasite's life cycle, so you will know why you are doing what you are doing.