Tank Mini Crisis HELP!

I have no idea what is going on with my tank this week. I lost my coral beauty yesterday.
She was fat and healthy and showed no signs of stress. She seemed to have kicked the bucket literally overnight with no indication as to why (have pictures if anyone wants to examine them).

In the past two days I have also lost about a dozen snails and all of my corals are closed up and looking pretty rough. All my lps have significant receding tissue. I have two mini carpets that are also looking pretty crappy. Something is obviously very wrong in my tank.

I tested all my parameters and some are a little low, but nothing major. My tank has always run a little on the dirty side.
Salinity - 1.025
Temp - 78-79
ph - 8.07
dkh - 8
ammonia - 0
nitrite - 0
nitrate - 10-15
calcium - 420
I didn't have enough regent to test for phosphate, so I guess that COULD be a problem, but I don't see that being the reason as I keep up on GFO replacement.

The only additions to the tank in the past 6+ months were a variety of snails about 3 weeks ago, and no changes in the tank itself as far as re-scaping or agitating the sand bed. No air fresheners or cleaner has been sprayed. I don't have kids that could have thrown something in the tank.

Water changes happen at least once a month at about 30-35%. Every water change I also change out the GFO in my reactor. I also run carbon, which get's changed out at water change as well. Filter socks are swapped out every other week or so ( I try to stay on better top of that and change more often, just doesn't happen).

In the process of looking for my meter to see if there is any stray current running through the tank, but I looked at all equipment in the tank and nothing seems to be broken or letting moisture in.

What am I missing?! Help!

**I do have a second tank up and running that is cycled and is coming down from the ugly stage..It has a blue headed wrasse and about 15 pounds of live rock in it. Would it be wise to move over all the coral I can or would that just cause more stress and further damage.

 

Well I moved all the coral that I could over to my second tank. I was thinking that second tank would eventually be a nice grow out tank anyways, just didn't think it would be this soon. Was it a hasty decision to move them over...? Maybe. But with as fast as things seem to be going south and not having the slightest idea as to why. I took the chance. My deciding factor was the brittle starfish. I can't remember the last time I saw them out and about, let alone during lights on. Well now they are ALL out and about, which I find very odd. Maybe I'm thinking too much into it, but there is something very wrong going on in the tank.

I can live with losing a fish or two. Would be a bummer, but I'd get over it. Now if I lost all my coral too, I'd be devastated. I was naive and a noob when I bought them and paid WAY too much for WAY too small of pieces. And now they are all nice and full. So they have somewhat of a special place in my heart and are a reminder to not be stupid again lol!
Here's to hoping I get this **** figured out!

 

Long story short-ish. Inspected heaters, magnets, power heads, and couldn't figure out what was going on. Everything was in working condition and seemed to be no cracks or defects. This past week while trying to figure what was wrong, algae came out of nowhere and just overtook everything (I'm assuming from a bunch of die off). I lost a total of three fish and the majority of my coral, which I didn't have a TON of, but still. Bummer. So I made the choice to do a complete tank tear down and start over. Which has crossed my mind a few times so far this year.

Well I figured out it was the damn return pump (which I didn't check before-didn't even think about the return pump honestly). I'm assuming. Last piece of equipment I disconnected and pulled it out and lo and behold....rust. :'(
So now what? I didn't plan on getting out of the hobby, just doing a complete redo of my tank, sump, and stand. But if there is rust on my return pump, does that mean it's no longer good, even though it works perfectly?
Not a whole lot of rust, but rust is rust.

 

As of right now I have no idea. I'm still in the process of moving everything down to the basement....Once I get done cleaning everything up, I plan on taking it apart and taking a look at the inside to get a better idea and go from there... and yes, it is a mag pump.

Side note...Had to go run a quick errand, just got back and man my entry room smells RIPE! Crazy how a running tank doesn't smell...but once you shut everything down and start tearing down and pulling stuff out...yikes! lol