What about calcium and magnesium and alkalinity?

I haven't seen any readings for alk, Ca or Mg. Are you testing these? With sps you may need to start supplementing.

Du'oh! You beat me to it Nano :D

There is a single Diamond Watchman Goby tugging along ,he never seened to get sick like all the other fish.

Calcium is above 20 mg/l

Thats as specific as it gets for now.

No clue on alk and magnesium.

All your fish have died, the tank is only three months old, and your SPS are dying? No kidding.
To keep SPS, you need a stable tank, older than 3 months if you're new at this, and you need to know Ca, alk, and probably Mg.
You also need to be able to keep fish alive before you can keep corals alive.

What happened to the fish? All die at the same time? Or?

I would say at this point, figure out the fish problem, then let the tank mature as you practice keeping it stable (measured by maintaining levels on the three parameters above in addition to PO4 and NO3).
Once you've got that, then think about corals...

The fish died from my own fault.

Everything has feeding well on NLS (aside from filefish) ,looking fine and dandy ,and I picked up a single fish and didn't QT ,and she made every single other fish in the tank sick. Everything died from it except for the goby. Hence all the fish dying.

Also the SPS isn't dying ,its just not doing as well :wink:

Also apart from the SPS ,all the other coral is doing fine. Acans are delightfully spewing out new heads and same goes for the Zoa's and Paly's. The Xena and friends are doing fine as well.

If you added a fish and it killed all the other fish, I'd suspect velvet. To clear that up, the remaining fish should be removed and the tank left fallow for 8 weeks.
You'll need to get test kits for Ca and alk at a minimum, they're important values for growing corals. The 20mg/l you mentioned above is either incorrect, or so low it might as well be 0. Ca needs to be about 400 or higher for corals, especially SPS. Which, if they aren't doing well, are dying. You may be able to reverse it, but maybe not.
I'd slow down a bit with the corals until you can manage stability in the tank. 3 months isn't long enough.

Well when you keep sps water quality is vital you need to know ppm not mg/l all mag and ca are very important to know

Very good to know.

I've got some decent quality test kits coming in now ,for calcium ,alk ,and mag.

Also for removing my last fish ,its been just him in the tank for the past 3+ weeks. Still take him out either way ??

Ya, I would. I lost all my fish except for a goby who didn't get affected, but they can build an immunity to velvet but still be a host. As long as there is fish, the velvet can survive. Took me a month to get the stupid thing out of the tank, then had to wait another 8 weeks.