Woke up with things dead! Causes?

Went to bed last night and everything was fine. Woke up to find two fish and both cleaner shrimp dead. These are the first two fish I have ever lost. Been in the hobby for a year and have never lost a fish until today.
Lost a Foxface and a Flame Angel
My mated Percs surived along with my small HumaHuma trigger.
Still MIA - Algae Blenny

I quickly did a water test

Ammonia - 0
Nitrite - 0
Nitrate - 10
Salinity - 1.0245

And then....PH - 7.4!

Nothing else is dead. Hermits/Snails are fine. Brittle star, scallop, pincusion, and most other inverts are fine.

Im assuming PH is the problem. So what causes PH to swing so rapidly?

 

I suspect the current pH value is a reflection of dying tank inhabitants. Rather the value is caused by the deaths not the other way around.

I am surprised you show no values for ammonia. Sometimes one fish and can die and it starts a domino effect as the fish release toxins and decays, this is especially true in smaller systems.

Did you dose or do a recent water changes within the last 24 hours?

Forgot to add that when a larger tank inhabitant dies, it may create a bacterial bloom that consumes available oxygen leading to another death and the cycle continues.

Sorry for the loss and frustration.

 

Possibly to little oxygen in the water can cause a big drop with it being winter and many having the house sealed up can cause carbon dioxide to rise and oxygen depleted,greater surface agitation and opening the house periodically will help bring "fresh air"into the house hopefully raising your ph.

Edit=that may not be the case as i just seen you are in Orlando

 

Well my wife woke me up saying something is wrong with the fish. I came out and the two fish were both struggling at the bottom. I stared at the tank in disbelief and watched them both pass.


Just a water top off last night. I make my own RO/DI water. TDS read 0.

I did dose. I used reef bugs last night, but thats nothing out of the ordinary.

The trigger was wedged under a rock in his usual sleeping spot. I could tell he was having trouble too. That was about an hour ago, when I found woke to find everything. Now he's swimming around like normal.

What flux kills two fish and two shrimp, but not a brittle star?

 

Yeah, Orlando has its perks. We acutally have the sliding glass door open all day.

Although I noticed that the return on my HOB fuge wasn't going when I woke up. Seems like the maxi-jet pump stopped working. This lowered the water around the chaeto and stopped the surface agitation, which could have lowered the oxygen in the water.

 

Ahhh,i think you may have found your trouble.

 

So not having that surface agitation for one night would lower the oxygen enough to kill the fish?

The pump could have been out for over 12 hours.


I got the pump working again. I'll monitor to see if everything goes back to normal. meaning PH level. If it does then I guess I found the problem

 

sorry about your fish

 

IDK,you may not of had enough gas exchange to have caused that.

 

The ironic thing is. Two days ago I removed a maroon clown from the tank to put in a mated pair of percs.

And while I was at it I removed a velvet damnsel too. Ironic I wanted them out of the tank so badly because they were picking on the other fish and it actually saved both of their lives.