Everyone else has added opinion..so guess I will throw mine into ring as well - as I went thru same gyrations when setting up first tank. ???
Cloudiness, in my case, was to very fine particulate in sand that did not get washed out all the way when I rinsed it. (and I rinsed alot).
Took forever it seemed for it to finally settle out - or my filters finally got caught it all.
With pumps running - I think I was just swishing it around and not giving it time to settle.
Continual cleaning of filters also helped get rid of the cloudiness.
Am going thru similar experience with latest new setup. But starting to finally clear up nicely. (after 3 days)
Rgds
OmarD