that would probably be a 30ml(g) per hour
300ml/hour is a commercial unit, and Compuchlor doesn't make those
chlorinators produce 100% chlorine, so to convert it to bleach you would need to multiply by 100 and divide by bleach concentration
so 30g/hour is the same as 0.5L of 6% bleach /hour
maybe they rate their cells in 10% bleach, hence 300ml in their specs