hey taz.. i went thru the exact same thing as you did with cloudy water..
I filled my tank originally with plain tap water to check for leaks in my plumbing to and from my sump to my DT. After my leak check i drained the whole thing and wiped out both my display tank and my sump (no chemicals at all)..
After that i started filling the tank with ro
water that i made here at home.. I had absolutely nothing at all in the tank but my protein skimmer and return pump and after 2 days or so my water got cloudy.. I dont know why either
So, i just started to mix in my salt and i let that run for 2 days to mix up in my tank with my heaters on at this point..
I then put in my sand/live rock/base rock and a couple of shrimp 3 days ago to start cycling the tank and it is still cloudy but it has gotten a little better everyday..There is just a little cloudy water now after about 8 days from the initial start up of the tank..
I couldn't find any answers to why the tank was cloudy right from the beginning and i looked all over the internet..
There was Plenty of info why it gets cloudy after you throw all the sand rock and everything else in due to algae or not rinsing your gravel or sand properly , but i didn't find much help in figuring out why it gets cloudy with nothing at all in the tank.. I will keep you posted on how my turns out.. Im hoping for the best and it seems to be cycling the way it is suppose to right now.. GL