All my fish died, why?

[Wiz]

Could just be diatoms. But it's weird that they would go away at night

 

[stevo01]

In addition to not mentioning I use RO/DI I also neglected to mention the tank is 3 month old. Can there still be such a build up of hydrogen sulfide? But certainly I was stirring up the sand bed more then I normally would to get rid of whatever is growing on it. Speaking of that if I understand correctly @twilliard is suggesting its not diatoms but @Wiz thinks they might be? The color of it is brown on the sand bed not red or green. I'll do the test to see if I see any water changes and go from there. Thanks everyone for your input.

I think WIZ said dinoflagellates, not diatoms. When the bubbles pop it spells death.

 

[stevo01]

Here are 3 pics each taken about 2-3 hours apart. It's hard to tell that the whatever it is, is growing but I'll get another pic tonight when most of it will have gone away. It might go without saying but its this stuff that I stirred up with the sand when I did my water change. I still don't see bubbles. If you want anything else closer up pics, etc. let me know...

Actually in this last picture it looks like its getting a little less covered to me.

A diamond goby will sift your sand allllllll day long, and will go deep within it too. My sand bed stays nice and white 24/7. Just food for thought, and very sorry for your crisis :(

 

[Agamerce]

Sorry shornik. great lesson here out of this for me/others. Going to reevaluate my stock and sand monitoring.

 

[shornik]

I agree the last picture does look a little better. Are those daytime pics they are not very bright. If you could get more lit pics so we can see the algae or whatever clear that would be great. The growth rate definitely worries me. Does it grow on rocks and coral too or just the sand?

Those are daytime, I just took bad pics and didn't white balance correctly that's why you're seeing so ultra-violet. It's not on the rocks that I can tell, maybe a tiny patch in one rock which doesn't get much flow. On the rocks I see what I would say is regular green algae and the start of nice pink coralline algae. As its getting later I can already see the "whatever" receding. I'll get a pic of that later and then tomorrow I'll post some macro, well as macro as I can get pics of the stuff.

 

[shornik]

So here's the last pic for tonight, you can tell most of the stuff is almost gone, if I remember and I'm awake I'll take one more once lights have gone out for a while and then the stuff will be almost completely gone, and then the cycle will continue. So at any rate, its this stuff that during the water change was all up in the water so could that be what was toxic to the fish?

 

[shornik]

Forgot to say thanks to @stevo01 for that suggestion. I was actually looking at a twinspot signal goby that are also sand sifters. I'm just hesitant to pull the trigger on any fish until I understand what happened.

 

[Wiz]

I think dinos would be worse than it got. But I can't believe diatoms would come and go that quickly. I'm stumped.

 

[stevo01]

Your welcome friend. Just be prepared for him to do what he wants with the sand. I gave up trying to keep coral frags on my sand bed. I do once in awhile level out spots that get too high. Going into the setup I planned on this goby, so I made sure all my base rock was on the bottom before the sand went in. He's very peaceful and allows my skunk to clean the mouth and gills. He has dug out several holes. Fills them in at night then digs them out during the day.

 

[shornik]

OK this is my last picture, its from early this morning after lights have been out all night. You can see the sanded is pretty clear though there are a few smallish patches of the stuff.

So from everyone's input I think either a) I hit a pocket of hydrogen sulfide which was toxic to the fish when I stirred up the sand bed. I'm discounting this mainly because the tank is so new and I did stir up the sand bed (maybe not to the same extent) multiple times before, but who knows I don't know enough about reef chemistry @Randy Holmes-Farley (hint, hint) to know if there could be such a toxic build up in so short of a time. Also its not a deep sand bed ~ 2 inches. b) the stuff on the sand that is a mystery was toxic when I stirred it up and that killed the fish. I don't think it was a lack of food even though the tank was new and the fish were only eating pods, there were and still are a lot of pods in the tank and I was feeding 2x a day with baby brine.

So the only question I still have is what to do with the stuff on the sand bed.

Thanks for everyone who provided valuable input on this and while it mostly still remains a mystery I hope it still might be at lear a little help to someone else.

 

[Tahoe61]

I would be surprised if a tank two months old had enough pods to sustain those fish types unless you were adding pods weekly.
The only variable that works against the starvation cause is that typically not all the fish die of starvation in short order, one after another.
You're right the tank seems too young to build up hydrogen sulfide pockets. What type of filtration are you using?
It seems more likely that there was a disease process going on.
Just curious what temp does the tank run at?

 

[shornik]

I would be surprised if a tank two months old had enough pods to sustain those fish types unless you were adding pods weekly.
The only variable that works against the starvation cause is that typically not all the fish die of starvation in short order, one after another.
You're right the tank seems too young to build up hydrogen sulfide pockets. What type of filtration are you using?
It seems more likely that there was a disease process going on.
Just curious what temp does the tank run at?

The tank is at 75 F, all params are normal, there are still pods + I was adding baby brine 2x a day - I really don't think they starved and like you suggested certainly not all at the same time. I just did a cleaning of the pumps and sump and pods are all in the sponges I use for filtration (its an Innovative Marine tank, and I use there sponges, phosphate, carbon and mechanical). I don't think there's a need to do a huge water change but will keep to my 10% weekly change for now.