Whats the best way to clean the filter?
I usually just rinse it once a month with fresh water and scrub it with a toothbrush.
I heard vinigar is a good way?
Not sure though.
Replace the filter pads monthly, but rinse them weekly (tap water is fine)
NEVER rinse the biowheels in fresh water (certainly not tap water). You can dunk them in old tank water every so often to remove the "gunk."
Every few months take the filter off and rinse to remove gunk. Clean the impeller to ensure maximum pump performance. If you see buildup of calcium carbonate (eg like hard water) then white vinegar is fine. White vinegar should also be used to clean swing arm hydrometers regularly.
Thats good info.
I heard that running the filter 24/7 can contribute to higher nitrates.
I do not have this problem, at least not at the moment.
Any feedback on that?
No. That does not cause higher nitrates.
Lack of proper care, overstocking, overfeeding, allowing gunk to build up in the filter, lack of export (eg skimmer, water changes, refugium) cause nitrate problems.