Dissolved gasses near disaster.

[Randys]

I just performed my weekly fin level water change on my 3 year old 90 gallon Mbuna tank. The parameters are always stable. 0,0, and nitrates never reach 40. I have well water so it's good and hard just the way the Africans prefer.

I've always noticed bubbles forming on the inside of the tank while refilling the tank (including the fish) but have never thought much of it until today. While refilling I noticed all of the fish were breathing hard. Their mouths were moving continuously. One of my big, healthy, pretty male Dolphin Mandas started acting weird, darting around the tank, and then just laid on the bottom. Soon he was laid over on his side.
Everyone seems to be back to normal now. The Dolphin is moving around the tank but I'm not sure if he's gonna make it. The long terms effects on all the fish can't be good. This is heart breaking. You think you're doing everything correctly then something unexpectedly like this jumps up and bites you in the butt.

Is there anyway I can avoid this? Letting fresh water sit in storage for a day or two sure isn't appealing.
Can the gasses be removed by aerating the water while it's entering the tank? Would the gasses be reduced to an exceptable level if I reduce the amount of water I change?

Thanks for the help.

 

[Drstrangelove]

I don't know if that was a DO issue, especially as it's well water.

However, changing less water at a time or spraying the water against a strainer or irregular object (a rock for example), above the water, not in the water should help reduce the amount of DO that enters the tank.

 

[Allan01230]

you using prime with your water changes?

 

[duanes]

If cool water is in pipes (well water or not), because cool water has the capacity to hold more gas than warm, those gases are under pressure, and compressed, so do not "gas off", until they reach the tank.
If when you add new water to the tank add it on an area where an air stone pumping bubbles thru the stream, or over a pile of rocks, the agitation will speed up off gassing.
When I did the water changes in the US, I always add new water to the sump instead of the tank, in that way new water is pulled thru the pump first which helps off gas. I also would run it tru a biotower such as the one below, where the cascading action helps speed up off gasing.


In Milwaukee water temps coming from the pipes were always cold (high 30s to 50sF), and even when mixed with the water from the water heater, was still super saturated with gases, and had the capacity to create gas bubble embolism in fish.

 

[RD.]

I live in North Western Canada, the water coming out of the taps here is cold year round, in the winter, uber cold. My water changes in all of my tanks is fin level, and fairly saturated with gases. I have never once in my life seen or heard rumour of, anyone losing fish in this area to gas embolism in a fish. So unless someone's water is for some reason supersaturated with gas, I'm not so sure that gas embolism is the cause. It's possible that the OP might have something else going on with his tap water.

Did any of their eyes bubble out since your water change? Any bubbles in their fins, or anywhere else? That is usually a sign of acute gas bubble disease.
http://www.advancedaquarist.com/2014/8/fish

 

[FLA]

While uncommon there are a few things that can cause super saturation issues. The temp issue is not one I have encountered, but wells here run in the 70's. I suspect it would take a pretty good temp gradient to do this though. Probably one greater than you would put your fish through. especially with fin level water changes. Another cause can be well water under pressure being brought up from great depths. I doubt this is your issue as that would likely be something you would always deal with.

When it has been an issue for me I can usually trace it to a leak in the suction side of my pump. If you have an above ground well pump take a look at it while it is running and see if you notice it sucking air anywhere. If so then that is likely the cause. Another source could be cavitation on the pump where it is sucking air. Both of these can cause the pump to force air into the water at levels above saturation. This rectifies itself once the water is no longer under pressure and the fish experience what you saw or worse. Depending on the type of filtration you are using it could happen if you get air trapped from letting your filter pump cavitate while filling the tank. This might explain why it happened after the water change and then stopped.

A far less likely scenario is that during your water change you created a venturi effect that pulled in too much air. I seriously doubt this. I cannot imagine you accidentally holding your hose in a manner to maintain a venturi long enough to super saturate your tank. An extremely violent addition of the water could cause the same thing, but I doubt you are doing that to your fish. In nature water falls can create a supersaturated area in the immediate discharge point.

All of the things I have discussed can be handled by aerating the water as you add it in. I use a garden sprayer and splash against the side of the tank for good measure.

The final question is are you actually dealing with super saturation? Bubbles forming in your tank or on you fish may just be aerated water forming bubbles. (Something I see from time to time when I do large water changes especially if the water is added at a rapid rate.) Bubbles forming inside your fish is a super saturation issue. Were these bubbles on the slime coat or inside the fins and under the skin?

 

[Randys]

I live in North Western Canada, the water coming out of the taps here is cold year round, in the winter, uber cold. My water changes in all of my tanks is fin level, and fairly saturated with gases.

Do you experience bubbles forming on the inside of the glass or on the outside of the fish?

 

[Randys]

When it has been an issue for me I can usually trace it to a leak in the suction side of my pump. If you have an above ground well pump take a look at it while it is running and see if you notice it sucking air anywhere. If so then that is likely the cause. Another source could be cavitation on the pump where it is sucking air.

No, I've got a submersible well pump at the bottom of the well.

 

[Randys]

The final question is are you actually dealing with super saturation? Bubbles forming in your tank or on you fish may just be aerated water forming bubbles. (Something I see from time to time when I do large water changes especially if the water is added at a rapid rate.) Bubbles forming inside your fish is a super saturation issue. Were these bubbles on the slime coat or inside the fins and under the skin?

I didn't see any bubbles forming under the skin of the fish, just all over the outside of the fish along with the glass.
But like I talked about above EVERYONE of the fish were laboring very hard to breath and it seemed to be especially rough on the Dolphins.
I've noticed the Dolphins being affected by this in the past and didn't realize what was happening. One fish in particular would lay up against a rock in an unnatural fashion right after a water change.

 

[RD.]

Do you experience bubbles forming on the inside of the glass or on the outside of the fish?

On the glass, yes, year round. Some on the fish as well, but never "under the skin" as one would see if there was super saturation taking place. FLA gave a great break down of potential issues.

Try smaller water changes, more frequently, hopefully that resolves your issue. Fin level water changes aren't for everyone.