crashed tank, does it need to cycle again?

[miatang]

Around 2 weeks ago my 72 gallon reef tank which was flourishing up to that point,started showing signs of something very wrong, fish started to die and corals were closing up. I immediately transferred what livestock I could to another tank I had running and was able to save a couple of fish and 1 coral. Within 2-3 days, even the B-worms had come to the sand surface and died. I cleaned out what I could that was dead and did water changes. I had the water tested at a LFS and it seemed fine. They even tested it for copper and it was negative. LFS thought that something must have fallen in tank to poison it. I emptied the tank this weekend, stirred up the sand, and vacuumed as much of the yuck on top of the sand I could but found nothing strange. Cleaned out the filter, replaced heater with a new one in case it was damaged. I then put all new saltwater in it and replaced the live rock which was kept damp overnight in separate bins.

 

I am on the fence about if this tank needs to cycle again since I have all new salt water. While trying to get all of the yuck off the sand, I did use straight fresh water with some Prime to vacuum up.

 

Am I truly starting from scratch again?

 

Any help you could give me would be greatly appreciated.

 

Thanks.

[dsoz]

The only thing you can do is wait and test it. There should not be a HUGE cycle, but even damp/towel on the LR can cause some die-off. You will probably get a small cycle out of this event.

 

Sorry to hear about your crash. I hope you can recover from it.

 

dsoz

[impur]

Welcome to the site!!

 

Its possible you could see a small cycle like Dennis pointed out. I imagine if you have enough LR you should be ok. But only with testing will you really know.

 

Good luck