Please help, tanks not looking so good

[andreethegiant]

I'm new to saltwater, I started with a 20g with a aqua110 made into a refugium. I upgraded to a 30g a little over a week ago and still had the aqua110 while I turned my 20g into a sump. Everything look great. Last night I hooked up my sump, I also bought a pistol shrimp and a open brain coral last night. Everything seemed to be ok when I went to bed, my temp made it back around 78. I woke up today and all my corals are closed and discoloured, my brain coral is mucusy, my fish are unhappy. My temp was down to 76 when I got up(not sure why..) but its at 78 again. I did a test kit: ph 7.8-8(lower then normal.) ammo 0-.25 nitrite 0 nitrate 10-20. Salinity is fine. I got 2 buckets mixing for a water change today but I'm just curious if anyone knows what's wrong?
Thanks

[ckmullin]

How long has the system been up and running? Seems like nitrate is high for a SW tank. FW it'd just be perfect though.

[andreethegiant]

Almost 8 months, still pretty new.

[andreethegiant]

And the nitrates went up when I upgraded, I was thinking from the old sand possibly..

[ckmullin]

It seems from my reading a rule of thumb is to ditch old sand as it will hold items exactly what you are having an issue. Perhaps some small dead critters were in the sand.

[andreethegiant]

I got rid of the old stuff and put all new sand in, I just thought maybe it came from the sand getting stirred up when I took the rocks and what not out of the old tank