Its important to clean your dishwasher filter once a month. If you rinse your dishes off before placing in dishwasher, it will prevent additional build up on filter. If you do rinse, great! But, you will also have hard water build up. All filtering systems in the dishwasher are not the same but its just as east with one as another to clean filters. 

I use a family members toothbrush, not my own. Just kidding. Use an old toothbrush and vinegar and lightly brush filter, at times I soak in vinegar. the process is the same with all dishwashers. If your dishwasher is different then the ones in the videos below just go to YouTube with your make and model for a search.

Cleaning your dishwasher is not considered as normal wear and tare, Its important to to understand that cleaning a heating filter, a toilet, a tub, drains or any other item of use is the responsibility of the tenant, not the landlord.   

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Link Video, Several