Wipe out

Y
180 gallon tank
Soft coral

After I did a 30 gallon water change about 20 min later I notice 3 dead chromis and by other fish gasping for air what could be the cause of this.

All I did was change filter socks clean protein skimmer and scrape the glass

All the fish dead but crabs n shrimp alive.

What could it be all chemistry seems to be good
Salt level at 22-24

Well prob has something to do with your water if it was right after that.

What kind of water? What kind of salt?

Can you give more info please?
What water did you use for the water change? Was it tap water? Where/what was the make up water stored in, and for how long? Any chance that something may have been introduced with out your knowledge? What did you use to scrape the algae?

Can't imagine what would kill all the fish, and yet not harm the invertebrates.

What is the pH of the tank?

Clearly something is wrong with the water from the water change..do you have any of it left that you can test for pH, ammonia?
OR something was on the filter sock you added..how was it cleaned?

also did you maybe use a chemical to clean the filter sock or anything else

The thing that popped into my head is the use of tap water and forgetting to put conditioner in. A friend of mine used BAD conditioner... He lost all his fish but all inverts lived. Basically the same exact thing.... Fish were dead very fast..

This is like saying, ya my car is broke. It makes a clicking noise, what could it be?

How did you wash your Sock? How did you exactly clean your skimmer? Plus +1 35's comment.

Care to remotely elaborate?

Either the water change bucket or the socks were contaminated at some point. Is the container covered? Where do you store it? What do you use to clean the socks?

Ha...the OP posts a question, clarification was asked for about 1 minute later and no response from the OP

He is on the job right now, i am sure hes trying to figure the problem out on site by himself first, and when he gets the chance i am sure he will take everyons opinion into consideration. some people actually work and dont hang on the website all day waiting for responses.

Used ro/Di water Tds zero
Filter sock wouldn't deplete all o2 in water

I used that same water on three tanks one 500 gallon tank with over a hundred fish n they were fine

I use tropic Marin salt

No conditioners

And I only did 15 gallons on a 180

Who said all the o2 was depleted? If you have a skimmer, i wouldnt worry about that being an issue.

So again for a second time, how exactly did you clean the sock and protein skimmer? Bleach? Water? Other chemicals?

Tap water wouldn't kill fish

Tap water will most def kill fish! The chlorine and all other other crap in there will do them in.

The sock I clean once a month a big bag I use bleach n let them sit for a long time then rinse before use been doing that for years never an issue on the 50 tanks I take care of

The protein skimmer I use my hand while it's on so the stuff floats to the top

No chems I don't even put lotion on lol

There must have been something in the bucket that the SW was in.....

yea i agree with thirty, it has to be the source water. but whats weird is that all the fish died and the inverts and corals are fine. that doesent make sense.

Anyway its either something in the water or a sudden burst of stray voltage

Jesse, there was obviously contamination somewhere along the line. Just think back to what you did and where and what might have been going on in the house. Was someone cleaning something else? Was something carried through the room that might have come in contact with the water? etc.

At this point it doesn't really matter what happened because the damage is done, just do a few water changes and run carbon until things turn around. If it gets, worse remove what livestock you can until you figure out what to do. Still try to figure out what happened so you can avoid it next time.