Unhappy coral

[Vesper6]

Hi all-

Tank: My tank is new (about 6 weeks now), 55 galllon tower running a canister filter with GFO and GAC, Reef Octopus HOB Skimmer, a single Tunze Nanostream 6450, and Fluval 15000k LED lights. I have approximately 25 pounds of live rock and another 30 of reef rock.

History:
1) My fish are currently in ich treatment in the QT, so all that is in the tank are coral and invertebrates (lots of small snails, about a dozen hermit crabs).
2) 2 weeks or so ago, I added my first coral - a chunk of rock that had Zoanthids and Anthelia growing on it. Both opened up relatively quickly and were doing well (low position, moderate flow).
3) A little over week ago, I added a few more coral: hammer, GSP, and a chunk of Live Rock with red mushrooms on it. All opened up within a day or so and everything was cool.
4) Earlier this week I wanted to clean out the canister and put in some GFO/GAC (previously just had a carbon pack and some bioballs). Also during this I wanted to cut down my hoses so the siphoning to the canister would work a bit better. This ended in misery (and blisters) trying to disconnect them. I ended up having to order a new disconnect valve for the filter. So for 3 days, my tank had no filtration from the canister (skimmer only).
5) During the days the canister was off, I saw a very minor ammonia spike (.25 ppm) which may have been caused by the live rock with the mushroom, or removal of some of the bio filter.
6) Wednesday, I added some amquel to the tank to protect against the ammonia spike as well as added some RO/DI to top off the tank.
7) Thursday, several of my corals didn't look great. The hammer was fully retracted and sliming, the GSP was fully retracted, the zoas looked OK, mushrooms OK, and the anthelia was rapidly shrinking.
8) Thursday night I did a 10 gallon water change and hooked up the new disconnect and got the canister back online. While doing this, I noticed the tank's salinity had dipped to 1.021 (too much RO/DI on my part).
9) Water change with new saltwater brought the salinity back up to 1.024 over the course of several hours.
10) Today, the hammer is doing better although not fully restored. GSP looks great. Zoas look great. The anthelia, however, looks very poor. Still fully retracted and barely moving. I just checked all of my tank parameters and they are as follows:

Ammonia: 0, pH: 8.0, Nitrite: 0, Nitrate: 10, Salinity: 1.024, Calcium: 400, Phosphate: 0.25, KH: 12

So my questions:
1) Did the coral take a dive because of a drop in salinity? I didn't get a chance to check the nitrate before the water change so I'm not sure how that was. Or maybe the slight ammonia spike?
2) What should I do for my anthelia? I know most people consider it a pest but since I'm just starting I'm liking seeing it in the tank. I noticed a small spot of decay on one side of it - I don't know if that means it is doomed already or not.
3) Any other advice on this situation?

Thanks for the help!

PS- There is some hair algae in my tank right now (on the glass) that the clean up crew seems to be getting rid of, but I just wanted to mention it.

 

[FullBoreReefer]

A few things, the salinity probably stressed them if it happened fairly quick, or the addition of the gfo to quickly or to much for your system. GFO is safe for reef tanks if added slowly and properly. Keep up on your water parameters and everything you have should recover, everything you mention is fairly hardy.

What is your water change schedule like? Maybe cut it in half, time wise and gallon wise. So instead of lets say 30% monthly, how about 15% biweekly. Or even smaller yet, like 5-10ish percent weekly for this month, then go back to a normal schedule.

 

[Vesper6]

For GFO I followed the amount suggested on the container from Bulk Reef Supply to start. 1 TBSP per 4 gallons. Note that the GFO was added after the coral started having issues.

Oh and another question: Is it bad to have snails/crabs walking on the corals from time to time? I noticed the GSP usually retracts all polyps when this happens but it seems inevitable with a clean up crew around.

 

[FullBoreReefer]

Ive never used gfo to be honest. Its just what ive read...

As for your invert question, is it bad? No, its life. Corals retracts of coarse to being touched but no harm. Once your system and corals are happy they wont mind much and just reopen after the inverts move along.

 

[Vesper6]

Updates:

1) Anthelia showed some minor signs of coming back today. A few of the polyps are getting bigger.
2) Hammer is still not entirely happy. Polyps are not fully extended (maybe 30% of what they should be).
3) GSP is as happy as can be.
4) Mushroom seems fine
5) Zoas never had a problem during any of this.

I'm worried about the hammer, but am debating between "leave it alone" and tweaking parameters. I've tried redirecting the flow a few times to make it more 'moderate.' It's about half way up as far as height and has some minor bit of shadow from a live rock.

 

[FullBoreReefer]

Just let things sit for a week. Moving things around only upsets your system. Be patient. My colt coral has taken almost a month and a half to get full polyp extension after being put into my system. I placed it, let it sit a few days, didnt seem happy, relocated and seemed alittle happier. I left him be and a month or so later hes back to normal.

 

[Spyderturbo007]

It sounds like there were a lot of changes to your system in a short time. Instability is one thing I've found that no coral appreciates. I suspect the main issue was the ammonia spike. I would also recommend that you address the high phosphate / nitrate. I don't see them as being an issue yet, but they are "getting up there" in concentration.

Personally, I would tackle the phosphate with GFO and the nitrate with some water changes.