CLEARWATER — Miguel Angel Garcia of Tampa thought he was traveling to Clearwater to meet with a 14-year-old girl he messaged online for sex. Instead, he was arrested and charged with traveling to meet a minor.But just hours after being released on $5,000 bail from the Pinellas County Jail, Garcia, 33, was seeking sex from girls in chat rooms again, Pinellas Sheriff Bob Gualtieri said. He is among the "plethora" of predators seeking sex from minors online, he said."This, unfortunately and sadly, but realistically, occurs every single day over the Internet," Gualtieri said Monday during a news conference. "These people don't get it, and this is the problem that we face."Garcia was one of 18 men arrested during a four-day child predator investigation called "Operation Guardian" that targeted people seeking to have sex with girls between the ages of 12 and 15, the sheriff said.Organized by the Pinellas County Sheriff's Office and the Clearwater Police Department, the investigation also involved other agencies, including the U.S. Department of Homeland Security and the Internet Crimes Against Children Task Force.During the sting, which started Thursday and ended Monday, investigators working out of the Clearwater police station posed as preteen and teenage girls on dozens of websites and chat rooms, including Craigslist and Backpage.com. They set up meetings with suspects in three undisclosed Pinellas locations.Most of the men, between 22 and 70 years old, live in Pinellas County, but some traveled to Pinellas from outside the county, including from Tampa and Holiday.Charges included traveling to meet a minor, possession of child pornography and unauthorized use of a computer.Among those arrested was Alex Wheeler, 26, who is on active military duty, the Sheriff's Office said. He will face charges through the U.S. Air Force.During the third day, deputies arrested Christopher Stephens, 31, of Largo, who thought he was meeting a 12-year-old girl. Investigators also found child pornography on his cellphone, as well as a rape video game on his computer, Gualtieri said.Operation Guardian was the second sting of its kind conducted by the Sheriff's Office and Clearwater police. From Jan. 23 to Jan. 26, another investigation netted 36 arrests.Gualtieri said this month's sting didn't lead to as many arrests because investigators were working 10-hour days instead of 12-hour days, Internet access in the conference room where the "chatters" were stationed was down for several hours during one day of the operation, and some investigators were receiving training."We'll continue to do these," Gualtieri said, "until we make a dent in this."Contact Laura C. Morel at [email protected] or (727) 445-4157. On Twitter: @lauracmorel.