Does it need to be sucked out from time to time?

If used correctly there should only be a need for it to be cleaned out very infrequently.  However, this will be necessary more regularly if sand, plastic, sanitary towels and other non-biodegradable items are allowed to clog up the system.  Overloading with organic wastes (e.g. more than 35 kg of food waste on a single day) will also necessitate more frequent emptying.