Protein Skimmer Power Bar Failure Death Toll....

[kien]

Ya, if you've got other forms of oxygenation like surface agitation or an overflow into a sump a skimmer flaking out shouldn't nuke your tank so quick. However, if you don't have any of the above and the protein skimmer is the only thing oxygenating your tank then you are in trouble if it goes. If the tank is relying on the skimmer like this and the skimmer goes your fish can and will likely die.

[ensquire]

Coral Banded shrimp is now Nem treat

[Binare]

Whats your ammonia at right now?

[outacontrol]

What is the temp of the tank, the higher the temp the lower the oxygen capacity of the water is and the wasted the metabolic rate of the fish is.
I do not think the death is from the skimmer failure, I have 7 fish in a 33gallon tank that has no overflow, no sump, no skimmer and I have no problems. I have an mp10 turned way down and a koralia that's it that's all. With weekly water changes everything is awesome.
How often do you do water changes? Do you have a lid? What about salinity swings due to evaporation?

[kien]

Consider also that the fish are not the only things consuming oxygen in your tank. Nitrifying bacteria and algaes will consume oxygen as well. Further, at night (when this skimmer died incidentally), some algaes will breath and consume oxygen contributing to the oxygen depletion.

Also, oxygen saturation will occur somewhere between roughly 6 and 8 parts per million in a saltwater tank while this number ultimately depends upon temperature, salinity and elevation. Temperature has the most effect, higher temp means lower oxygen holding potential of the water as outacontrol mentioned. This means that the water molecules have absorbed as much oxygen as they can easily hold under the present conditions. Any more oxygen added will be released back into the atmosphere.

Ultimately you have to get oxygen into the tank somehow. It doesn't have to be a skimmer, or an air stone, or a powerhead, but something has to add oxygen to the water. If the tank relied on one source of oxygen (whatever that source was) and that source happened to go and your tank was now consuming more oxygen than what is being added, you can reach a point of deprivation.

Occam's Razor.

[Megalodon]

What are your water parameters?

[ensquire]

Temperature 79
Specific Gravity 1.025 1.024
pH 7.9 8
Alkalinity 220 mg/l 196.9/1
Ammonia 0 0
Nitrite 0.1 0.01
Nitrate 20 20
Phosphate .5 .5

Last 2 reading prior
will update
Appreciate all the help.

[ensquire]

And I might add that the day before everything was looking very healthy.
I didn't do any tests but HONESTLY are there not days you just look at your tank and say "OH YEAH"

[daniella3d]

the oxygen depletion from the algae must not be that bad because I have tons of macroalgae in my tank and I shut down my skimmer at night. No problem what so ever. I really have lots of caulerpa. When it goes sexual all my water become cloudy white and sometime I wake up to a very cloudy tank but nothing seem affected. I start the skimmer and it goes away in few hours. My coral seem to even like the spores.

My temperature is 76F though, so I guess that surely help to keep a good level of oxygen in my tank. Bioload in 75 gallons: kole tang, niger trigger, copperband butterfly, clownfish, 3 pajama cardinal, green mandarin.

Maybe it was a combinaison of a few things?

Originally Posted by kien

Nitrifying bacteria and algaes will consume oxygen as well. Further, at night (when this skimmer died incidentally), some algaes will breath and consume oxygen contributing to the oxygen depletion.
Occam's Razor.

[Aquattro]

The thing with oxygen is not adding it, but removing CO2. any water surface movement should off gas the CO2 in the system, making the water absorb more O2. If the power heads were causing any type of water surface movement, you should have been fine. Lots of tanks run without a skimmer at all, and do just fine. Not sure what to look for, but I can't see this being from the skimmer turning off.