Had some bad luck with one of our reef tanks...
Early in my days as a reef keeper I was quick to pick up any and all coral I could get for cheap and wasn't picky about dipping or quarantining it. As a result all of my reef tanks are invected with flat worms. The 120gal tank by Stratton's front office has corals so infected the flatworms are significantly affecting growth. I siphon and pull out corals and dip them but I've never been able to completely remove the worms. One of my spring break goals was to deworm my tanks with salifert flatworm exit, a product many have told me was completely reef safe.
I started with the tank with the least amount of flatworms. This tank has a 90 gallon display and a 60 gallon stand alone refugium connected to it. I disconnected the refugium and drained 1/3 of the display tank, saving the water. As per the instructions, I siphoned off all the worms I could see and dipped the corals I could easily remove from the tank. Then I treated the remaining 60 gallons of water with a 60 gallon dose of flatworm exit. I increased the flow and after about 5 minutes, flat worms started detaching and floating around in the water column but there will still many visible on the coral. As per instructions, I waited 30 minutes and then added 50% more medication, waiting an additional 15 minutes. At this point I started to get concerned about my fish and did a 30 gallon water change, added the 30 gallons I took out originally, re connected the refugium, and starting running two canisters of carbon.
So the full volume of this system is about 150 gallons. Only about 60 gallons were treated with the flatworm exit and of that 60 gallons, only 30 remained after I did the water change and reconnected my system. This 30 gallons of contaminated water, plus the 45 minutes my livestock was exposed the neurotoxins the dying flatworms extruded was enough to kill most of the fish in my tank!
15 minutes after reconnecting my system and getting the water circulating again, my fish started to come out of the rock work and were clearly impaired. Many were lying at the bottom of the tank moving sluggishly and I was able to literally pick up them up.
Over a period of about 5 hours, all of the tangs in the tank and some of the other fish died. It sucked because I had to stay up most of the night, pulling out each fish as it died so it wouldn't put the system under more stress. One managed to work itself into the far back of the tank and I had to take out most of the rocks and coral to get it out.
My purple tang was a rescue fish that had made an amazing recovery after being almost killed by lateral line disease and poor husbandry. It was one of my kids favorite fish.
I lost 13 fish, more than a $1000 work of stock my kiddos and I had to save up for, just to get rid of some worms. And guess what I saw on the glass the next day when the lights came on...
I followed the directions to the letter and will never use Salifert Flatworm Exit again and will just learn to live with the worms.
Moral of the story: No Chemicals