stopping 210g freight train

I came home thurs night and things were not good.my butterfly was swimming on his side like a sideways pinwheel and all of my other fish were gasping. My test kits are at my gfs house and shes out of town so im flying almost blind.I have my apex with ph and Orp.ph is stable at 8.13 but my Orp was down to 38. I quickly ran for the prime first incase its water quality that may help. Next I started up my water change pumps.I keep 55gallons ready at all times.next swap out the carbon for fresh new rox 8.0.while I'm waiting for my rodi to make more water I finish my DIY ozone reactor and get that online.Orp rose to 60 after alittle time passed.new water was ready after afew hours so i did another 50g water change.I'm now low on salt,called my buddy to bring me some aswell as Polly pads....after 300 gllons of water changes I'm down 1 blue hippo tang,yellow tang,harlequin Tusk,ember blenny,starry blenny,algae blenny and a ph cardinal.all of them only had 1 post mortum symptom,their belly/chest area was slightly swollen and white.when these fish were dying they all did the same thing swam on there side in circles ...from just breathing heavy to death in a matter of minutes....its now sat 3 days later with the help of my ozone set up I'm at 238 Orp and my survivng fish seemed ok this morning but the lights are out so I'm just seeing with the room light ...any input what this could be?

 

That quick of demise with the gasping sounds like it's was low oxygen for some reason.....my tank crashed with my fish showing the same symptoms and it was pretty much all of them and it happened overnight...I knew the cause though - I ran biopellets without sufficient skimming. You are lucky that you had the ability to have the ozone. I only had one survivor and I ran an air stone in my powerheads, kept the lights off, and the lone survivor did make it. I wish I could help you figure out what caused the oxygen level to decline though.....

 

What kind of inverts are in the tank? This happened to me when a cucumber got caught in the powerhead on my one of my tanks. All corals survived but it wiped out all fish.

 

How long have you been working with ozone? Your orp meter is unquestionably out of calibration. Everything in your tank would have died with an ORP of 38. Bacteria, plankton, fish, corals. Everything.

If you aren't extremely comfortable with ozone and how it works you need to stop using it immediately.

 

Don't you have a Sea Apple in the tank?

 

No dangerous inverts in this tank.to many expensive fish,just reef safe snails urchins ect.also 2 mantis in the Sump ...I thought the Orp was very low I was thinking the prime may have contributed to it.I'm comfortable with ozone first time on this tank not my first time using it though.I've only been running itthe ozone when im watching the tank its on a controller but still temporary plumbing and not leak tested yet.I'm thinking what ever got in the tank may have tinkered with the probes reading.sea Apple is a future venture for my rsm tank ...what ever did the damage seems to have subsided.Orp back at 310 and the survivors look mostly normal.