tank crashing, help!

erisedstraeh

New member
So yesterday I came home to 3 dead fish and no idea why so I am looking for some insite from you guys. Here are my tank specs:

46g bowfront
Stocking was 2 clowsfish, royal gramma, yellowtail blue damsel, diamond watchman goby plus ton of snails and crabs
3 small corals
Fluval 406 filter with phosguard added
35-40lbs live rock
live sand
been running for 1 year with no issues

Checked my water peramiters on Sunday before a water change and everything was normal. Phos 0, pH 8.4, nitrate 0, nitrite 0, ammonia 0, spec grav 1.024

I did a 20% water change on Sunday (I make my own water with my RODI unit and about 3 weeks ago changed all the filters in RODI unit including RO membrane. TDS is 0). I usually do 20% water change every other week and that has been working well for the tank. I also changed my filter media (charcoal and phosgaurd) which I do once a month.

All my fish were happy and swimming around on Sunday night, ate when I fed them. Monday when I got home from work I found 3 of my fish dead (the gramma, goby and damsel). checked my water peramiters and everything was the same as before Phos 0, pH 8.4, nitrate 0, nitrite 0, ammonia 0, spec grav 1.024. temp is steady at 78 degrees.

No idea what happened. Any ideas of things I should look into? The only thing going on is I have a moderate amount of Diatoms at the moment that I have been dealing with for about 2 weeks.

side note, I have nano tank that I use the same RODI water for and everything in there is perfectly fine.

I'm just looking to see if anyone has any suggestions or ideas because I have no idea what happened.
 
Go to your fish store, get water, put all your fish and surviving critters into a spare tank, bucket, whatever you've got, and oxygenate and heat it.

There are several possibilities, including contamination, toxin in the water, electric shock, a toxic substance in the air, or oxygenation failure. You also didn't list your alkalinity. [8.3 is good]. If you can get PolyFilter, put a square of that into the water flow and see if it turns colors. Main thing is get what's alive to good clean water. You might also ask your lfs for a device to test 'stray voltage', ie, a cracked heater case or other way for electricity to charge the water.

Meanwhile have the fish out, and start testing for problems. Describe your rig: skimmers and water-fall and fuges provide oxygen---any shortage? Any lit candles or household sprays or cleaning agents near the tank?
 
That's strange. I'm sorry to hear about your losses.

I would add some fresh carbon (again) and some PuriGen, if that was easy enough, in case something got into the water. I see that you added fresh carbon (not charcoal?) on Sunday, but I probably would replace it. I might check for any signs of metal contamination: a broken heater, a cracked magnet or pumps case, etc. I doubt that metal contamination is the issue if the corals are all doing well, though. I'd also check the ammonia morning and night for a day or so more.

The tank might have had some sort of short ammonia spike. Clownfish are tolerant of ammonia. Oh, sigh!
 
Thank you for all the great suggestions guys! I'm going to do some further investigating with everyone's suggestions. Appreciate the help!
 
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