Importance of oxygen in the water

[jim barry]

Now i know how much rays (and other fish in general) need good oxygen levels in their homes. But i have seen a post on a site from a guy that has had his entire stock in one tank wiped out over night. Stock includes 2 rays, dats etc. Not a huge system but a decent sized tank of the sort us ray keepers run. The person states the loss of the stock was due to an air pump packing up sometime in the night for around 7 hours or so. He does not state total power failure of the entire system, just the air pump.
I am baffled that the entire stock was lost due to one air pump. Or am i being thick?
Are our beloved rays etc really that reliant on one air pump and the oxygen it provides. I understand that they need it but would have thought that surface agitation of the water from return pumps etc would be enough to keep occupants alive for more than a few hours.
I managed to get my system down to one air pump to save on electric, but if we can not afford to lose the air for a few hours, i may have to dust off my secondary pump and restart it back up!

 

[predatorkeeper87]

Sounds to me like that air pump was the only surface agitation he had in the tank. if the drains on his sump were submerged, and I'm guessing no HOB's or powerheads facing the surface, then that was the only means of oxygenation in the tank. Alwayyyys have surface agitation of some other degree besides airstones or pumps. That's the only reason I have an airstone in my sump, moves the surface around in addition to my drain lines being above the water line. That coupled with a powerhead pointed on the surface in my main tank and I have no oxygen issues even if my airpump fails, which it has.

 

[MHDevelopments]

A mate of mine sent me the pics of the tank, before and after and told me what happened.
Does look like the only surface agitation was the air pump. Had he had returns from the filtration above the surface I imagine this would not have happened. Tank looked fairly well stocked.

Shall I post the pics, they're not mine obviously.

I have ordered today a second pond sized air pump for back up.

 

[predatorkeeper87]

A mate of mine sent me the pics of the tank, before and after and told me what happened.
Does look like the only surface agitation was the air pump. Had he had returns from the filtration above the surface I imagine this would not have happened. Tank looked fairly well stocked.

Shall I post the pics, they're not mine obviously.

I have ordered today a second pond sized air pump for back up.

+1 Yes even if the return line was the only other means he'd have probably been alright, he essentially had a closed-loop system, no oxygen in other than the pump.

 

[Woefulrelic]

I'd be certainly agree with the two before me. With no surface agitation gas can't exchange and if the tank is stocked more than lightly the effects will become apparent very quickly. Afaik the amount of air that actually diffuses into the water column from air pumps is up for debate.

 

[jim barry]

Yes this is what i was thinking guys (glad i am not thick then lol).
My drains to the sump are below water for noise reduction as are my returns, but one return points up and breaks the water surface a little. The other 2 returns are below water pointing down. However, the water going over the weir combs to my drain lines drops around 2" before hitting the drain lines (sound is muffled by japmat). This provides enough agitation (I hope).
Think i may direct one of my circulation pumps to the water surface tonight, just to be on the safe side. I don't want to start running another airpump if i can help it. Having said that i may start up a small one say around a couple of hundred liters per hour which is way too small but also very low power consumption and run this in my sump. Would this be beneficial to the main tank? Or again, am i being thick lol?
Mike, i would not post pics unless you have the guys permision mate. I would have thought he is pretty gutted right now.

 

[predatorkeeper87]

Yes this is what i was thinking guys (glad i am not thick then lol).
My drains to the sump are below water for noise reduction as are my returns, but one return points up and breaks the water surface a little. The other 2 returns are below water pointing down. However, the water going over the weir combs to my drain lines drops around 2" before hitting the drain lines (sound is muffled by japmat). This provides enough agitation (I hope).
Think i may direct one of my circulation pumps to the water surface tonight, just to be on the safe side. I don't want to start running another airpump if i can help it. Having said that i may start up a small one say around a couple of hundred liters per hour which is way too small but also very low power consumption and run this in my sump. Would this be beneficial to the main tank? Or again, am i being thick lol?
Mike, i would not post pics unless you have the guys permision mate. I would have thought he is pretty gutted right now.

As long as the water is being oxygenated somewhere in your system you would be fine. You could even make due putting a circ. pump in your sump and have it splash the water around in there. The water will return to the main tank well oxygenated for your stock. It makes me wonder now that you mention the weirs/overflows of how much o2 gets dissolved into the water during that process. I have internal overflows with weirs near the surface, the water falls a good 2-3 inches as well. Can't be that much of a difference.

 

[MHDevelopments]

Yes this is what i was thinking guys (glad i am not thick then lol).
My drains to the sump are below water for noise reduction as are my returns, but one return points up and breaks the water surface a little. The other 2 returns are below water pointing down. However, the water going over the weir combs to my drain lines drops around 2" before hitting the drain lines (sound is muffled by japmat). This provides enough agitation (I hope).
Think i may direct one of my circulation pumps to the water surface tonight, just to be on the safe side. I don't want to start running another airpump if i can help it. Having said that i may start up a small one say around a couple of hundred liters per hour which is way too small but also very low power consumption and run this in my sump. Would this be beneficial to the main tank? Or again, am i being thick lol?
Mike, i would not post pics unless you have the guys permision mate. I would have thought he is pretty gutted right now.

I agree Jim, poor bloke must be devastated.

Nothing much to gain from seeing a tank of fish the right way up and the wrong way up in the next pic

 

[jim barry]

As long as the water is being oxygenated somewhere in your system you would be fine. You could even make due putting a circ. pump in your sump and have it splash the water around in there. The water will return to the main tank well oxygenated for your stock. It makes me wonder now that you mention the weirs/overflows of how much o2 gets dissolved into the water during that process. I have internal overflows with weirs near the surface, the water falls a good 2-3 inches as well. Can't be that much of a difference.

Well if just water movement and surface aggitation in the sump is good enough then i am well in!! I have water falling around 2" through a foam layer in the last section of my sump before hitting the return pump. I also have other water lines just moving water around in another area of the sump where i grow stuff out. So i think i am good to go as i am. Phew!!

 

[jim barry]

I agree Jim, poor bloke must be devastated.

Nothing much to gain from seeing a tank of fish the right way up and the wrong way up in the next pic

Absolutely Mike. Did not want to hassle the guy but want to learn exactly how it happened. It baffled me that just an air pump going could wipe out his entire tank. Some lovely fish too. Feel sorry for him but this is how we learn by sharing experiences and when i asked him exactly how it happened i did not get a very clear answer. Don't blame him, the last thing on his mind is sharing with people what went wrong so we don't make the same mistakes.
That is why i posted the question, so we can all learn.