K6200 in combination with a 24/7 digital timer

I am looking for a timer device (K6200???) to switch a pump on and off. I need to be able to alter the runtime of this pump (misting pump) between 30 and roughly 60 seconds. The pump should switch on on a four hour interval. Eg. six timer a day.
The setup I was thinking of is a regular “of the shelf” timer device (wired infront) programmed to give a contact every 4 hours to the K6200 Velleman timerdevice. The minimal contact time is one minute. Will this impose a problem for the K6200 if it is set to a ON time of LESS than one minute?
Can I substitute the standard potmeter (220K) for one with a knob so I can change the ON times from outside the enclosure?

Thanking you in advance!

Frank

Check K8015, it is better suited.
http://www.velleman.eu/es/en/product/view/?id=341552

Thank you for the reply.
The kit you mention will not work for me because I need to be able to alter the time ON instead of the time OFF. The ON time must be easily adjustable without to much knowledge of programming dip-swithes etc. A larger knob potmeter will do the work fine and can be installed in such a way that opening the project enclosure isn’t nessesary.