, It's prob a combo of your SG
, Nitrates and Iodine.
Iodine is nasty stuff and should not be added unless you test your levels first. I lost almost $300 of corals, fish and inverts from an Iodine OD. I only added 1/3 the recommended dose. But since I didn't test, I didn't know my levels were fine. So when I added, I OD the tank.
swings will definitely cause issues. Slowly bring it back up to at least 1.023 and keep close tabs on it. How do you think it got that low?
Inverts are intolerant to Nitrates. Now, yours aren't THAT bad..but mixed with the SG
and Iodine..could very well have overwhelmed it.
I've had my shrimp for just about a year now, and they are still kicking.