Hi. I'm not quite sure what you are asking (google translate) but if you do not mod sump, your skimmer chamber is 35cm length, 25cm deep. Water level is 20cm tall, cannot be higher due to overflow into Return pump chamber.
Return pump chamber is 35cm x 12cm BUT it is wrong because of Auto Top Off Float device.
Real Return chamber size is 24x12cm.
If you throw away Reefer ATO (use Tunze 3155), then you have 35x12cm.