Duncan closed, low Nitrates

[UnnamedReef]

Hey everyone, new to this forum as a participant but I've used a lot of the info on here to get started. Happy to join the community! I'm an experienced freshwater fish keeper but this is my first saltwater tank.

The tank:
- 55 gallon
- ~20 lbs live rock + 1.5" sand bed
- 2 months old
- cycled fishless, fed empty until ammonia rose, then nitrite, then nitrate. Water changes to bring it back down to near 0. Diatom bloom subsiding from past couple weeks.
- 2 Ocellaris clownfish, 1 cardinalfish, 1 emerald crab. All healthy, colorful, and active.
- RODI water changes with measured TDS of 3
- x2 Smatfarm G5 fixtures on recommended mixed reef intensity/schedule
- 3x weekly phyto/zoo plankton dosing + reef fusion 1/2 dosing as well


Parameters:
Ammonia: 0
Nitrite: 0
Nitrate: 0, or really close.
SG: 1.025 (too high for mixed reef?)
Temp: 78 degrees
pH: 8.0
Calcium: 440
dKH: 8-9

Problem: Duncan coral (purchased from petco) recently closed and hasn't opened for a week. Bought with two-ish heads and half open. Wasn't expecting much, but it has since grown 2-3 other heads, opened vibrantly for 3 weeks straight, and enjoyed mysis shrimp and pellet feeding 3x weekly. During a water change I accidentally missed salt addition in one bucket, so I added directly to the tank. I know now that's a mistake I won't repeat, and my Duncan didn't enjoy it. He closed up, and hasn't re-opened but he seemed less lively that day before the water change. I've heard Duncan's are finicky, looking to get him open again. He doesn't LOOK dead or dying, but I'm no expert. Moderate flow area towards the bottom of the tank. Could having very low Nitrates make him close up for low nutrients? All productive advice appreciated, thanks everyone!

Shayne

 

[TX_REEF]

you could try giving it a dip to eliminate any hidden pests. also, make sure it isn't getting blasted with flow or intense light, this is a common cause for LPS closing up. Your SG is fine, I actually run 1.026. Also keep an eye on your emerald crab, I caught mine in the act of actively feasting on an Acan before moving him to the sump.

 

[UnnamedReef]

Thank you for the reply! I thought my first post didn't go through so this is actually a duplicate post. He's reasonably far away from the filter return, slight poly swaying when open. The emerald crab was introduced yesterday so he didn't factor into the initial closing up. I got a female, hoping it plays nice with it's future tank mates! I can try a light reduction, he's the only coral so I won't be affecting anyone else

 

[Uncle99]

Parameters look good except two, nitrate and phosphate.
You post zero nitrate which is too low, bump to 5-19ppm and no post on phosphate which should be 0.05-.15ppm

These two nutrients are a must as they feed everyone, including corals.

 

[Reefkeepers Archive]

I know that my Duncan will do this if there is a change in tempature, did you recently raise/lower the temp?

 

[UnnamedReef]

I've halted my water changes and stepped up my feeding to try to drive nitrate and phosphate up. I agree I need those to be above 0 to have any success with coral.

About the temperature, I'm using a heater from one of my last freshwater tanks that might be quitting on me. Set to 82, was maintaining at 80, and I just checked and it's 76.5. heaters are cheap enough, I'll get the temp back to 80 and see what happens. Thanks!!