Updated info for dying fish post

[amphitrite]

Here's the situation-I have a 72 gal for 2 years. Wet/Dry filter and also an over the side filter. 2 powerheads. Did have 6 damsels,2 urchins,2 mushrooms,LMBlenny, choc chip starfish, snails/crabs,live rock,sand/coral bottom. I put a coral beauty with more snails/crabs in on Sept 29th (~3 wks). Domino Damsel was aggressive and coral beauty hid mostly. Coral Beauty died 3 days ago and I took out the body (skeleton) but I figured it was stressed and not eating. My Domino was okay. Yesterday I noticed him swimming horizonally so I put him in a quarantined box in the tank. He died within 30 minutes. I can't find the Blenny and 1 B/W striped damsel. I do 10-15 gal water changes weekly. I can't afford RO so I put water in old CLEAN salt buckets to sit out for the week and add Amquel Plus to help the water condition before adding to tank. No drastic water temp changes that I know of. I have VHO light (the high output bulbs?) that put out enough wattage according to the lfs.
Here's the test I did last night:
Ca 220
pH 8.2
ammonia 0-0.25
nitrite 0
nitrate 0
salinity 1.022-23
I don't know what to do. Test kit is about 1-1.5 yrs old if that matters...I have persistent hair algae but the growth is slowly going down.
Today-everything seems to still be alive except the missing fish.
Any suggestions on what to do preventatively or what might have happened. How long should I wait before putting any new fish/inverts in the tank?

 

[perfectdark]

From the sound of it, your CB died from harassment and stress. Your tank had an amonia spike, and your other fish were affected by it. Keep doing water changes, test regularly if you can QT the remaining fish until your tests are normal again.

 

[amphitrite]

Thanks!