try using some filter floss or a filter sock to filter out the water of any sort of cloudy water, on new tanks the sand usually does have a resedue on it and you will require some mechanical filtration to get it out.
also another cause of cloudy ness is if the tank is not fully cycles the ammonia will cause a haze in the water, if all perameters are in check then look into a bit of mechanical filtration and maybe a bit of chemipure to clean it up.
i would also refrain from gettign a UV
sterilizer, it tends to burn whatever goes through it which means it can harm beneficial bacteria, or any critters that pass though it. you already have a refugium so leave it to the refugium skimmer and rock to do the biological filtration. natural filtration will keep things happy and less stressful