Besides Myka's good thoughts, I'll add my similar issues from the last few months (or maybe a bit longer)
It sounds like you may be having similar issues to mine and your tank is 'too' clean. I found out our corals need food, or they will bleach
My corals were bleaching pretty badly
I had zero nitrates and phosphates, so some fellow reefers helped me out
Our thoughts are that I wasn't feeding my fish enough, and not feeding my corals, so the corals expelled their zooxanthellae. Once the zoox are gone, there's nothing to protect the corals from my 8x54w light, so bleach away
I turned off half my lights, started feeding the fish double-time, and also started using coral frenzy, phyto plan and coral vitalizer
A couple of weeks and the corals were coming back
Now all are looking much better, and I'm getting the new algae under control
I've also started playing with my lights to get a happy medium between the corals and our viewing times
I see your lights are a total of 15 hours for 3 pairs
I knocked mine down from 27 hours for 4 pairs, to 19 hours for 2 pairs for a couple months. This worked very well for me and I don't think your lights are on too much
I'm currently running a total of (I think) 20 hours total with 4 pairs and all is looking good. It's been many months since I started making changes, so don't expect a quick fix
I also see you wash your socks daily. Do they plug up this fast, or are you just cleaning them 'cause ? I wash mine once a week. Maybe you're removing more nutrients here than you need to
And you run your skimmer very wet. Maybe it's of no consequence, but I run mine dry and only remove a few hundred ml/week, and the nog is very dark
Hope this helps some