Cat Rushing Up Side

add some old tank water from another tank
or just ask for a little from a pet stores tank they keep the water nice and dirty
 
Adding water won't do anything as very little bacteria actually reside in the water, mainly on surfaces (filter media, substrate, decor, etc.)

Read the sticky and keep in mind that you are in a fish cycle now. You will need a test kit (liquid, not strip) to monitor the params and do all the water changes necessary to keep both ammonia and nitrite under .25 ppm.
 
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