I have a most unfortunate incident to report and a HUGE mystery that as yet is still not solved. Hence, I have been hesitant and have done even more research on the marine keeping hobby.
I started a 55-gal tank in Aug 2001. I had about 70 lbs of various types of live rock, 4 inches of CC substrate, and Eheim 2230 canister filter, whose media I changed religiously every 4 weeks, a hang on Prizm skimmer, and four 4-ft flourescents (2 actinic, two daylights). I had in the tank about 30 or so turbo snails, 4 emerald crabs, 2 brittle stars, 1 sally lightfoot, 1 CBS, 5 peppermint shrimp, 1 percula (small), 1 sebae (small), 1 hippo tang, (small, he was going to be transferred to my 72 bow after that had cycled), and (1) 3 inch yellow angel. I monitored my levels daily, and buffered pH to be pegged at 8.2. I had undetectable levels of trates, trites, and ammonia. I did a 6-gal water change every week, and vacuumed the substrate weekly as well.
So it's Dec 30, 2001. I do my standard maintenance in prepartion for a new year's party to be held at my house on the 31st. I do my water change, verify salinity in tank to be at 1.025, check levels before I go to bed while lights are still on in tank. Everything appears to be fine. The fish are active, not breathing heavily. So I go to bed around 11 pm after one last look at tank when lights are out, and again everything appears normal, and levels check out fine.
I wake up around 9 am and saunter downstairs. EVERYTHING, except a few snails and hermits, is dead. The brittle stars are alive, but they don't make it past 11. I immediately check my levels, nitrite is off the charts, while ammonia and nitrate are still not detectable. PH still at 8.2, salinity still at 1.025 and water temp at 79. All pumps and filters are running, skimmer is working properly.
Here's teh big mystery, since Semptember 2001 when i began stocking the tank, I had done everything the same. Topped of tank daily with the same DI water, cleanded and maintained skimmer and pumps/powerhead the same. I was very proud of this tank, as it was my first one. I never added any medications to the tank or anything. I've spoken with several people, including people at the best LFS I have found in the Twin Cities, and no one can explain it. If anyone has any thoughts/ideas please don't hesitate to share them!
Sorry this post is so LONG!
nathan