Connecting multiple USB devices

I'm would like to connect two USB devices to my Arduino UNO. The devices are pH meters which stream data over USB. Essentially I need to get the data into the Arduino to control a servo motor. Can I use arduino's USB 2 Serial device? Or do I need some other kind of converter to get from USB to TTL?

Thanks

No, Uno is a USB slave, you will need a USB Master to talk to your pH meters, which are likely USB slaves as well.

There are other models of Arduino that can be programmed to act as USB master.