Are my corals dead?

[JoTaDe]

If correct, calcium range is 400-440
Increasing calcium will change Alk reading. Do the calcium increase first. Calcium and alkalinity levels are interdependent. The basic rule of thumb is when one goes up, the other goes down. For example, when the alkalinity level is high, the calcium level will likely drop significantly in the water which is likely happening in your tank

So I should something to boost calcium and that would fix the corals or do I need something else as well...?

 

[damsels are not mean]

Most likely lack of food. And food for corals in our tanks is mostly nitrogen (usually nitrate and/or ammonia) and phosphorus (phosphate) directly out of the water.

 

[JoTaDe]

So I should feed my damsel more and get some tankmates to boost nitrates?

 

[damsels are not mean]

So I should feed my damsel more and get some tankmates to boost nitrates?

That would help, can also dose nitrates but I think fish food is cheaper.

 

[Dav2996]

So I should feed my damsel more and get some tankmates to boost nitrates?

Your corals look closed which means not happy. They can be alive and not happy. They turn white when dead depending on the coral. I would feed frozen food and cut the cubes in half. If you just added them they could be unhappy for a bit. Zoanthids are easier to care for. I keep my nitrates in my tank around 10 but I have mainly lps and soft. I have 2 acros. I have a ton of coral to use the nitrates up though.

 

[JoTaDe]

Your corals look closed which means not happy. They can be alive and not happy. They turn white when dead depending on the coral. I would feed frozen food and cut the cubes in half. If you just added them they could be unhappy for a bit. Zoanthids are easier to care for. I keep my nitrates in my tank around 10 but I have mainly lps and soft. I have 2 acros. I have a ton of coral to use the nitrates up though.

I see, it may be a combination of me understocking the tank and not feeding enough, ill start incrementing feeding slowly to not have it go out of control, also I'm going to do some research to find a tank mate or two for the yellowtail damsel.