my turtle needs help

Question
my red eared slider turtle opens its mouth as if breathing constantly and white resado spits out of its mouth what do i do to help it it lives in a 40 gallon tank half water and it sort of floats off one side when swimming please tell me what to do.

Answer
First thing you need to do - is read my instructions when you ask the question. I have the instructions there for a reason. I cannot give an answer with what little you have provided, nor will I.

The first obvious answer, however, is to check your conditions, which I'm sure something is not right...then see a vet. If you want more info from me for free, you are going to have to do what I require in the instructions.