Can these pumps be PWM controlled to vary output flow?

Can these pumps be PWM controlled to vary output flow?

My question is specific to the UP3 series pumps and whether or not they can be PWM output controlled to vary output flow. The pressure is low (less than 15psi). Is there a recommend maximum PWM frequency? I was thinking 30Hz or less for this type of device. Also, I noticed on the 12VDC tag it says EMI filter inside..do not use with PWM, but the 24VDC version does not have this same warning. Can you please clarify?