A dying question?

[argan]

did you have airation in the bucket after you moved them?

[mike31154]

Some info gaps with respect to your water change regimen? Are you using tap water to make up your water changes or do you have a RODI system? I started the hobby using tap water treated to bind the chlorine, but it's not something I would recommend. One of the best investments I've made is getting a RODI system for purified water.

I do fairly large water changes, about 25 to 30%, all at once. If I understand your water change procedure, it does not sound very efficient, seems like a lot of extra work and you may be well advised to make some changes there. Not sure this is the cause of your crash, but it should help keep things stable in the future. By ?taking out 2 pails and adding 3 buckets over the course of several hours? are you not removing some of the freshly added water you added previously? Perhaps I misunderstand your procedure, but I think it's best to remove all the water you intend to in one shot, then add all the fresh in one shot. This may not be feasible the way you're currently set up, but I'd suggest, as mentioned already by another member, you get a larger container to mix and heat your fresh salt water. Invest in an extra powerhead and small heater to get the new water to the right temp etc. Allow the water to mix at least a day before your water change. Floating pails of freshly mixed new water in the tank to get them up to tank temp seems like a lot of extra effort in order to do a water change. Hope things work out a bit better for you in the future, best of luck.

[shimmy]

Yes I remove all the desired amount of water I intend on replacing first before I add any new water to the system and I picked up a rubber tub last night and just looking for an old powerhead to make the water changes more affective. Yes the way I do things is lots of work but I do not have lots of room in my condo to have a fancy setup.
I stopped using tap water and started using purified bottled water (the 5 gallon jugs that you fill up at the grocery store) about a week ago and never had any problem with that water. Is that bad water to be using for my thinking was if it is purified and good enough for me to drink why not them?

[mike31154]

Using the grocery store water is a good start, but ultimately it's going to be another chore and expense that would be better addressed by getting an RO DI system. I'm pretty sure that the water from the store is RO (reverse osmosis) only and it will still have some TDS (total dissolved solids) in it. The DI (de-ionization or demineralization by ionization) stage of a RO DI system will bring the TDS of your water to 0 so you're mixing your salt in absolutely pure water. Check out some of the threads and info on RODI systems and you will find plenty of information. The initial investment may seem costly and although I don't know what your store charges for the bottled water, in the long run you will have better results and save money with your own RO DI system, especially with a 72 gal tank. The trips to the store for water will get old fairly quickly. As mentioned I do fairly large water changes on my 77 gal, about 25 gallons each time and I would not enjoy hauling that amount of water from the store every few weeks.

[Marlin65]

Just a few thoughts to throw out there.
Do you have a ground probe. Maybe you have a short somewhere it will kill your fish.
What about that prime you added maybe it is a bad bottle and the chlorine killed them.
Also having the circulation off for the water change dropped your oxygen levels to low.
Just some things to think about.

[shrimpchips]

Perhaps I read wrong, but one thing that struck me is that you said all the fish are dying/dead but the corals all remained fine?

I've had SPS corals survive out of a bag that reeked of death and were probably off the chart in ammonia - but fish would have been dead in that water for sure so maybe you had an ammonia burn or something similar due to stirring up crap, and also having a lower total volume (due to water displacement by the buckets of water). Maybe you had a dissolved oxygen issue also? I find that a lot of mysterious mass deaths in the night can usually be attributed to DO issues.

That being said, this is one of those "crashes" where the source is going to be difficult or impossible to pinpoint. But a better water change regimen would be a good place to start.

[shimmy]

The deaths did not happen during the water change so having the flow off I still don’t see the chance of that being what was the cause. I tested for ammonia as soon as I had noticed it and found nothing on my tester and same with the chlorine testing. Im thinking from everything people have suggested is that I had too many fish in my tank for the age of it and to be aquascaping and playing around in my tank shook the ecosystem too much.

[FitoPharmer]

just wondering, what is your turnover in your tank? how deep and what size of sand do you use? are you running a skimmer? do you know how long was it between you moving your rocks and the fish gasping? and what was your PH after the crash?