i think my tank is crashing

[Atmos]

all of my corals are closed up, my urchins arent moving. the long spined urchins are dropping their spikes all over the place. even the aiptasia is all curled up in its holes. the fish are still swimming around and dont seem to be affected by whatever is causing this. i dont have any test kits with me so i cant check the parameters. the alkalinity is right on and so is the temperature of the water. i just did a 25 % water change and that seemed to help im going to do another one tomorrow. any suggestions?