Advice on my fish tank !

Hey everyone ! I’m new to fish keeping I’ve got a betta my tank is 27 litres

My tank water is quite greenish and a milky cloudy colour I’ve tested my water parameters there fine except from the PH is at 6.0
I used to have a hang on back filter however it stopped working so so I took the sponges out and placed in tank and replaced the filter to a jet filter it has a jet stream it working fine but I want to know how to make my water clear I’ve done water changes but it keeps coming back ? 🤷‍♀️🤷‍♀️