how should I polish water

[WWWD]

if you have particles floating in your water no chemical is going to remove that. it needs to be done mechanically with either filter floss or better yet a micron filter bag that you hang in the sump return. the filter sock/bag needs to go into the washer every 3-4 days but does an amazing job keeping particles out of the water column.

as for pods you should see them at night scurrying around the rockwork if you look with a flashlight. they will be noticeable if you have any.