TALLAHASSEE, Fla. -

The manufacture and sale of low-grade THC marijuana, known as Charlotte's Web, is expected to be a $200 million a year business in Florida. But regulators and bankers are already warning that finding a banker to handle the cash could be trouble.

Colorado pot stores do a brisk business. Armed guards stand ready at the door. But all the cash generated from sales is posing a problem for entrepreneurs and bankers alike.

Marijuana is still illegal under federal law and the banks are regulated by the feds.

In Florida, a 40-page glossy presentation from the Office of Financial Regulation is warning that banks could face a host of federal charges if they deposit cash from legal marijuana sales in Florida that will begin next year.

"There is a know-your-customer clause which doesn't allow a bank to actually bank certain entities if they are dealing with criminal activity," said Deputy Commissioner Greg Hila, of the Florida Office of Financial Regulation.

Florida bankers are already saying, "No thanks."

"We follow all federal laws and regulations, and as such we do not bank anyone related to the marijuana business," said Bank of America Florida President Mike Fields.

If voters legalize medical marijuana by approving Amendment Two, the problem is only going to get more complicated for everybody.

Pot was designated a schedule-one drug with no medical use in 1970. The sponsor of the Charlotte's Web legislation that passed this year said the designation has to change.

"It's been proven to be ridiculous by virtually every scientific study, and the federal government has failed the people of this country," said Rep. Matt Gaetz, R-Ft. Walton Beach.

The stakes are big: Nationwide, the sale of legal pot this year alone is expected to generate about $2.5 billion.

Florida, Ohio and Pennsylvania are all voting this year on legalizing medical marijuana. Alaska and Oregon will vote on legalizing recreational use.