Corals Sick?

I'm suddenly having issues with my tank. In the last 3 days, my green hydnophora has lost chunks of flesh and retracted all polyps. It's nearly dead. My beautiful pink and purple birdnest has completely died and lost all flesh. My duncans have retracted their polyps and barely come out and looks sick. I have noticed the flesh receding on one area of my frogspawn.

Other corals and inhabitants seem to be OK. I've noticed my kenya tree is dropping more branches than usual, but it's growing just fine.

I have posted my parameters below. Please let me know if you have any advice, as I really don't want to lose any more corals and the tank just doesn't look quite as healthy as usual.

PARAMETERS (important)
Temperature: 80
PH: 8.1
Ammonia: 0
Nitrite: 0
Nitrate: 10-20
Salinity: 1.025 (refactometer)
dKH/KH/Alkalinity: 9
Magnesium: @1400
Calcium: 440
Phosphate: 0
Test kits you own: The necessities
Liquid or Strips: Liquid
Brand Name: API
Are they Expired?: No


Tank size? 75
Estimated total system? @80

Reef, fish only or, freshwater? Reef

Current inhabitants? What and how many? 1 maroon clown, 2 YT damsels, 1 watchman goby, 1 diamond goby, 1 3" tomini tang
Clean up crew? Yes, the usual suspects

How long has your tank been set-up? 7 months

Substrate.
Type? Sand
Depth? 2 inch

Live rock? Yes
How much? 80 pounds
Did you recently add some? No

Filtration.
Type? Sump
Protein skimmer? Bullet 1
Do you wet or dry skim? If it skims, dry
Maintenance schedule for filtration? Once a week, clean skimmer, check reactors for detritus buildup
Drilled tank/hang on back overflow? Drilled
Sump/refugium. What's in it and how much? Sump - water, reactors (carbon, phosguard)
Macro? What kind? None

Lighting.
Lighting type? 2x250 MH, 4x65 PC actinic
Age of bulbs? MH - 3 months, PC 6 months

Feeding
What? Mysis / Cyclopeeze / Ocean Nutrition F1 / Omega 1 marine pellets / ocean nutrition flake
How much? 1 of each variety
How often? Every other day

Water change schedule.
How much? 10 gallons
How often? once per month
What salt brand? Instant Ocean / Brightwell Aquatics
Water source? RO/DI in house

Additives/supplements used? DT's - CA, Alk - Brightwells - MG
Do you have a ground probe? No
What kind of flow does your tank have? Closed loop, sump return, approx 3,500 gph total

Any additional info you would like to share.... Including anything different that you have done/not done.

I just recently changed to Brightwell aquatics salt, did a total of 15 gallons water change with new salt

 

Oh no! I have to ask.. do you have large peppermint shrimp.. Mine took a chunk out of my Birdsnest and decimate 3 heads of candy cane coral (picked em to the bone.. nuthin left).. That sucks man.. I hope you figure it out.. Any pics.

 

This is strange. I had some sps corals RTN for no apparent reason. Did you put your hands in the tank at all? Stir up the sand? Just change the media in your reactors?

 

I changed the media about 3 weeks ago. All has been fine since; I rarely put my hands in the tank. The last corals I added was a blastomus and watermelon mushroom. The other corals afflicted are LPS so I'm not sure what's happening...

I'm wondering if the Brightwells salt hasn't had some bad effects .

 

Me, too. Joe the Coral acropora is looking off, not great color and polyps look smaller. Possibly something with the new salt mix? I made a switch from Seachem Reef Advantage Calcium to Tropic Marin calcium and I think it wasn't good for the acro. Maybe the new salt is effecting some corals and not others. I also boosted my alk. up to 11 dkh from 8 dkh over a week or so, to try to get the acro to recover.

 

Thoughts on ground probe? Do you think stray current could be doing this? My tank has never tingled me but there may be stray current? I will see if I can obtain a voltmeter to test just in case. Any other ideas.

 

Im sorry to hear about your tank. You might want to do more water changes than just 1 10 gallon water change a month. I dont know if that is what is making your corals sick or not but I know I use to have problem's with losing corals for what seemed like for know reason, My water chemistry was all good but I kept losing coral. I started doing water changes weekly and I havent really lost anything since maybe you might want to try that it works good for me. That will also get you nitrates down a little more and make you coral's more happier. Keep us updated good luck.

 

Not hijacking, but I put my hands and arms (up to the pit), multiple times a day...what are the issues in doing so?

 

First thing that caught my attention was the salt change, chemical make up and nutrients may have changed dramatically. Consider going back to IO and change out some water.
Cant hurt.

 

It's a possibility. How are you inverts and fish behaving?