Did I kill my hammer/what am I doing wrong?

[DeadlyMuffin]

I bought a hammer coral about 3 weeks ago, that started out looking great. It looked good for about a week, and then two big problems:
1. I knocked it over, and about half of the coral closed up. Over the next week or so it seemed to mostly recover, but that side never opened up as fully again.
2. I noticed a little bit of algae growth on the back wall, which was a sign to change out my GFO. In the process, I managed to spill about a liter of tank water, and the ATO kicked on and refilled it with fresh water. I was worried about the salinity drop, so I (in my infinite wisdom) put a little bit of salt into the back filter, which promptly blew it right into the hammer.

The hammer now looks absolutely awful. Can I expect it to recover after this, or is it done for?

I'm pretty depressed about this whole situation, I've only recently been willing to even try LPS corals. I recently discovered ultra low phosphate meters, which led me to trying GFO, which caused my algae to disappear almost overnight, and gave me a big boost of confidence. The experience with the hammer has completely dashed whatever confidence I had.

I do water changes twice weekly (it's a 10 gallon, so 4-5 gallon changes are easy) I have an ATO, I run a skimmer, I run GFO and carbon, and as far as I can tell my water quality is great. I have a ton of light (2 Kessil 150s), but most coral I try either stagnates or very slowly declines. The only exception is a Duncan coral that's going absolutely nuts. What am I doing wrong here?

After ~1 day

Today

 

[RadReefer]

As far as I can tell from the picture your hammer just looks irritated. I would move it to an area of gentle flow and leave it alone for a while, hammers are pretty hardy and it should recover well. As far as your coral difficulties, it seems like you are running an ultra low nutrient system. You are changing almost 50% of the total volume during water changes, skimming, running GFO and carbon. Since it seems like you are only keeping LPS and soft corals this seems excessive. LPS and soft coral seem to be healthier and thrive better when there are more nutrients available in the water column. All coral, even SPS, require some amounts of nutrients to survive. I would ditch the phosphate meter and GFO. Stop chasing small bits of algae with GFO. This is most likely the reason you are having coral difficulties. You are stripping the water bare. GFO can really damage corals very quickly if over used. Some small amounts of algae are natural for any tank. You should control it naturally with snails, crabs, algae Blenny Etc.

 

[DeadlyMuffin]

I'm very glad you think the hammer will recover, I hope you're right

I'll try dialing back the GFO, but I don't want to remove it completely. I ran without GFO or carbon for several years and everything would end up getting overrun by some sort of creeping algae. It ended up smothering zoas and even GSP. Not hair algae, but some sort of shorter fuzzy stuff. I would even get cyano sometimes.

Adding GFO was a bit like magic, the algae stopped overgrowing everything, a big cyano outbreak stopped, etc.

Maybe there's a happy medium somewhere. I'll dial it back a bit.

 

[RadReefer]

Sounds like you know what you are doing then. I over used GFO and lost some SPS colonies but it does make a big difference with algae.

 

[trinidiver]

why are you changing 50% of water twice weekly. Its a ten gallon. That's way too much. no wonder the corals cant recover. Drop it to 2 gal bi weekly or 1 every week. you are shocking them with that large water change.

 

[DeadlyMuffin]

why are you changing 50% of water twice weekly. Its a ten gallon. That's way too much. no wonder the corals cant recover. Drop it to 2 gal bi weekly or 1 every week. you are shocking them with that large water change.

I used to do changes weekly, but I switched to twice a week because my LFS has a beautiful nano tank that's slightly smaller, and when I asked they told me they change the water twice a week.