Cloudy for weeks

Hi all
Can anyone help please? I have looked at the other threads and don't know what's happening. My tank is cloudy and has been for a a few weeks. I have no idea what an algal blooms looks like so I don't know if that is it. I have a 170 litre tank, 1m long and 3 axis, the biggest about 10cm. I use Prime and Stability and my tank is 6 months old and well cycled. I have even used the Seachem cloudy. My water parameters have been perfect for the whole time. Have double checked.
The substrate is sand . I decided to up the filter as the water was cloudy and i thought that might be the problem. I used the filter medium from the the old filter so as to keep the biology. Still nothing.
The water was beautiful and all of a sudden I can only see the axis if they are by the glass.
I have run out of ideas.
Please help if possible.
Thanks.
Emma

Post a picture if you can.
Is there anything you did different before the water went cloudy? Post your water parameters so we can double check it.
Usually the 2 reasons would either be a bacterial bloom or sediment from a substrate.
I'm not sure if the seachem cloudy is safe to use with axololts, so I would avoid it for now unless someone says otherwise.
Have you tried doing water changes to see if it helps?

Should I change the water???? More than 25%. The parameters are all good. Nothing is different.
Having trouble uploading files. It won't let me upload

How often are your water changes? More regular water changes might help this. Try 25% twice a week and see if there's improvement.

Thanks!
I did a water change today of about 50%. All water parameters looking good still. It's slightly less cloudy but still not great. See how it is tomorrow.
Thanks for your help.

YEs, when I've had a persistently cloudy tank I did frequent water changes until it cleared up.

Thanks. I put a tiny filter on the other side of the tank which I used ages ago in the same tank when I forgot to wash the sand! It is clearing slowly. At least I can see the plants now!
Thanks for help all. Newbee here so much appreciated.
Oh, btw, my axolotls are really my son's but he is only 8. There is Baby, Sunlight and Moonlight.