All fish dead after water change - what went wrong?

[UnnamedReef]

55 gallon tank, 2-3 months old, regular testing, water changes, etc.

Been having a problem with either diatoms or cyano (I think) so I took out some of my rocks yesterday and brushed them off with a toothbrush. The ones that weren't easily removed I brushed in the tank. Did a 30% water change, matched temp and salinity did not move more than 0.001. used RODI water with TDS of 3. Rinsed out the mechanical filter too.

One of my clownfish showed signs of distress, I thought it might be oxygen related so I added a bubble stone for the night. Kept the power head and Fluval G3 filter running as normal. This morning both of my clowns and my cardinalfish are dead.

Tested with API test kit this morning:
Ammonia: 0
Nitrite: 0
Nitrate: 0
SG: 1.026
pH: 8.0
Calcium: 460
KH: 8

Exact same readings I had before the change. Any idea what could have happened? Photos attached of what I was trying to scrub off

Shayne

 

[UnnamedReef]

The photos aren't good, but I was trying to remove that brown mucus like substance on the rocks. I got most of it, so the rocks look pretty clean now

 

[AndyS598]

Zero nitrates at 3 months old is a bit concerning? Also, diatoms/cyano at the 3 month mark is likely just the uglies mate, wouldn't have been worrying at all unless it was completely taking over your tank!

Any chance of something being on your hands when doing the water change? Chemicals or anything? What did you wash your chemical filter with? Possible with all the scrubbing and cleaning you caused an ammonia spike that has since sorted itself... But I'd expect some nitrate to be showing...

 

[Rewd]

Scrubbing cyano or diatoms will not kill fish like that. My money is on chlorine in your tap water getting past your RODI somehow. I did that to a freshwater tank a couple years ago after a water change and wiped out an entire tank in less than a half an hour. When I spoke to the local water guys they did tell me that sometimes municipal water agencies will occasionally spike the water supply with a higher level of chlorine on a seasonal basis.

Given you DO have an RODI in place, I am not sure the likelihood of this, but I I will say, your RODI is not fully functioning if you are seeing a TDS of 3.

 

[LeDart]

55 gallon tank, 2-3 months old, regular testing, water changes, etc.

Been having a problem with either diatoms or cyano (I think) so I took out some of my rocks yesterday and brushed them off with a toothbrush. The ones that weren't easily removed I brushed in the tank. Did a 30% water change, matched temp and salinity did not move more than 0.001. used RODI water with TDS of 3. Rinsed out the mechanical filter too.

One of my clownfish showed signs of distress, I thought it might be oxygen related so I added a bubble stone for the night. Kept the power head and Fluval G3 filter running as normal. This morning both of my clowns and my cardinalfish are dead.

Tested with API test kit this morning:
Ammonia: 0
Nitrite: 0
Nitrate: 0
SG: 1.026
pH: 8.0
Calcium: 460
KH: 8

Exact same readings I had before the change. Any idea what could have happened? Photos attached of what I was trying to scrub off

Shayne

Your rock looks fairly new, same with your sand. If I may ask, how old is your tank? Also I tend not to rely on API tests, they are fairly inaccurate, and hard to read. I recommend spending a little extra on a more reliable test kits, like a Salifert, Aquaforest, Red Sea, or Hanna Instruments. Hanna is the most expensive of them all, but it is what I use and I find then to be very precise, accurate, and easy to read results.

 

[Randy Holmes-Farley]

Possibilities include ammonia that has now dropped, chlorine or chloramine from the new salt water, or hydrogen sulfide stirred up from under rocks and such.

 

[LeDart]

Your rock looks fairly new, same with your sand. If I may ask, how old is your tank? Also I tend not to rely on API tests, they are fairly inaccurate, and hard to read. I recommend spending a little extra on a more reliable test kits, like a Salifert, Aquaforest, Red Sea, or Hanna Instruments. Hanna is the most expensive of them all, but it is what I use and I find then to be very precise, accurate, and easy to read results.

Scratch that first question, I didn't see the age at the top, sorry. I would not trust the measurements too much, but the 0 on all nutrients is very concerning. I would also consider changing your RODI filter's media, as a TDS of 3 means it is not functioning to it's fullest extent.

 

[UnnamedReef]

Thanks for the fast replies everyone. I was also concerned reading 0 nitrate without being able to raise it (extra feeding, etc). I thought it was consumption from whatever algae or diatoms were in the tank, which was a large reason why I tried to eliminate them. There's always a chance something was on my hands but I can't think of anything aggressive that would have been.

Just re-tested my RODI and got a TDS of 0 or 1, it was fluctuating.

 

[UnnamedReef]

My coral (Duncan and zoa's) don't look too good either. Should I do more water changes in case something got into the tank, or would I be doing more harm than good?

 

[Uncle99]

My coral (Duncan and zoa's) don't look too good either. Should I do more water changes in case something got into the tank, or would I be doing more harm than good?

Water change sure if you’re concerned.

You did use 3ppm RODI, which is usually just fine, however we don’t know “what” that 3ppm was in this case.

But after, let your system stabilize and consider dosing up nutrient levels so all things don’t starve. This will advance the population of good guy micro stuff which feeds our corals and processes our water.

 

[UnnamedReef]

Well, Im definitely concerned. I'm going to do a decent water change since my corals look so shocked. I did retest my RODI and got a TDS of 0 or 1, so I think it's working properly.

My Aussie pipe organ (which I got 5 days ago and hasn't opened) is finally showing polyps today. They're out, but I wouldn't call them healthy looking. Does this give any kind of clue about what happened?

 

[Randy Holmes-Farley]

Does the tank water have any sort of rotten eggs smell to it?

 

[jda]

It was probably from the rock cleaning moreso than the water change, for whatever reason.

In general, don't do too many things at once in a reef tank. Not only is this less stress, it is also allows less things to go wrong and then you know what happened if they do.

Pipe organ is a delicate and tricky coral, especially for a new tank. If this coral dies, then do not be too alarmed since it could be nothing that you did. The algae growing on the top of the pipe organ skeleton is concerning since the polyps are not usually tough enough to fight this off.

 

[Troylee]

Run some carbon and wait for a water change.

 

[Sophie"s mom]

Thanks for the fast replies everyone. I was also concerned reading 0 nitrate without being able to raise it (extra feeding, etc). I thought it was consumption from whatever algae or diatoms were in the tank, which was a large reason why I tried to eliminate them. There's always a chance something was on my hands but I can't think of anything aggressive that would have been.

Just re-tested my RODI and got a TDS of 0 or 1, it was fluctuating.

I agree with the others about your RODI water. Mine reads at about .001 .

 

[UnnamedReef]

No rotten egg smell to the tank, just smells like saltwater. The algae growing on the pipe organ skeleton was the type I was trying to rid the tank of. One lesson I learned over and over in my freshwater tanks was to not change too much, but I guess that didn't sink in properly. I'm going to wait this one out and hope I don't lose any more live creatures

 

[Malcontent]

Scrubbing cyano or diatoms will not kill fish like that. My money is on chlorine in your tap water getting past your RODI somehow. I did that to a freshwater tank a couple years ago after a water change and wiped out an entire tank in less than a half an hour. When I spoke to the local water guys they did tell me that sometimes municipal water agencies will occasionally spike the water supply with a higher level of chlorine on a seasonal basis.

Who are "local water guys?"

 

[Spare time]

My coral (Duncan and zoa's) don't look too good either. Should I do more water changes in case something got into the tank, or would I be doing more harm than good?

The corals may be unhappy from a lack of nitrogen or phosphate.

 

[Reefering1]

FWIW, some growth on the rocks is not a bad thing. Bare white rocks is no goal to keep

 

[TX_REEF]

how many and what fish did you have? did you happen to test parameters before the water change? I'll echo what others have said, 3 TDS after RODI is not normal, do you have a pressure gauge on the unit, and how old are the filter components?