# fluval disaster



## teemee (Aug 29, 2009)

Hi,
Was wondering if anyone might be able to tell me what went wrong with my brand new fluval U2 - 
just got back from holidays, but right before i left, switched my external elite filter over to my 35g to work with in tandem with an eheim, and put the fluval in my 20g...
well, pretty much straight away, (but of course right after i left) fish started dying. I did a good clean and about a 3g water change before i left, but still it was a well established tank, so i wasn't too worried about adding a new filter.
obviously should have done this all a few days before i left... 
anyway, just got home, and all of the few surviving fish from the 20g had been moved into the 35g amazon tank, and maybe 100 RCS of maybe 300 were left in the 20g.
so i did a major cleaning and water change in the 20g, and moved some fish back slowly.
well, what do you know, this morning some fish dead, and shrimp deaths.
looks like no oxygen was getting to the bottom of the tank, with all of the survivors at the top of the tank... Its as if the fluval wasn't plugged in... but it was, as was blowing my xmas moss all over the map. the tank wasn't overpopulated, and the U2 is supposed to support up to 45g... 
couldn't get through to hagen support today when i called, but am going to try again tomorrow. 
anyone have any ideas as to what it could be?? btw, the filter had been in for 2 weeks.
(switched an old external on and the shrimp are back on the bottom - but am so annoyed about this am probably just going to shut down this tank for a while...).


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## ameekplec. (May 1, 2008)

If all the fish and shrimp were near the top of the tank, it may be that the filter return (spraybar) wasn't creating adequate surface agitation for gaseous exchange.

With my folk's 75g, the eheim spraybars have to be fully out of the water to create sufficient gas exchange or else oxygenation problems begin to occur - all the fish start huffing and puffing at the surface of the tank, the plecos all com to the surface too, and the shrimp and snails all crawl up the glass or hang out at the top of floating plants.

Try running the return from the Fluval out of the water to create more surface gas exchange.


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## teemee (Aug 29, 2009)

*fluval*



ameekplec. said:


> If all the fish and shrimp were near the top of the tank, it may be that the filter return (spraybar) wasn't creating adequate surface agitation for gaseous exchange.
> 
> With my folk's 75g, the eheim spraybars have to be fully out of the water to create sufficient gas exchange or else oxygenation problems begin to occur - all the fish start huffing and puffing at the surface of the tank, the plecos all com to the surface too, and the shrimp and snails all crawl up the glass or hang out at the top of floating plants.
> 
> Try running the return from the Fluval out of the water to create more surface gas exchange.


Hi Eric,
Thanks for the suggestion. Will give it a shot...


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## Tbird (Oct 5, 2009)

Was that the only filter you had on the tank? I'm thinking that maybe because if was brand new when you put it in, it did not have enough time to build up any bacteria in it.


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## GuppiesAndBetta (Jul 27, 2009)

+1 To both the posters above
1) Lack of oxygen could be one thing
2) The filter did not have beneficial bacteria in it


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## qwerty (Dec 15, 2009)

> but still it was a well established tank, so i wasn't too worried about adding a new filter.


A well established tank with an uncycled filter is no longer a well established tank, it's a cycling tank, and most likely an overstocked one.

That would be my most highly suspected cause. The only information you provided that suggests otherwise is that any of your shrimp survived.


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## teemee (Aug 29, 2009)

*fluval*

yes, i know, my bad...
but the filter should have bacteria in it by now (shouldn't it?)...
doesn't explain why things started dying again after i re-housed them in the tank. post clean-up, and water change.
the bottom was a dead zone - both literally, and in the true sense (oxygen deprieved).
things are again fine with my crappy elite ext. filter.
but the posh, much more expensive fluval really hasn't worked out for me.


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## KhuliLoachFan (Mar 8, 2008)

You should never just swap a new filter for your old one. The nearly the entire biomass of your cycled tank's bacteria colony is inside the filter sponge. You must run BOTH filters for at least a month before moving it, or you fill the new one with entirely old used media. So that's problem #1.

You do have a test kit and you can test for Ammonia, Nitrites and Nitrates right? Any non zero reading on the first two indicates your tank is now starting cycling all over again.

If you want an instant-ready-to-go cannister, get cycled media for a fluval, get some from someone, OR you have to run BOTH filters in tandem for at least a month. Then your "luck" will change.


W


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## dl88dl (Mar 8, 2010)

teemee said:


> yes, i know, my bad...
> but the filter should have bacteria in it by now (shouldn't it?)...
> doesn't explain why things started dying again after i re-housed them in the tank. post clean-up, and water change.
> the bottom was a dead zone - both literally, and in the true sense (oxygen deprieved).
> ...


A filter will not be fully mature until 2 to 3 months later so actually you should thank that posh Fluval that save you some fishy and shrimps. 
Getting those fishy and shrimp out of the 20gal was a good thing but putting them back in is a very bad thing since your 20gal has not yet completed the cycle. Your 20 gal was not lack oxygen but the fishy and shrimp were exposed to high level of ammonia and nitrate poisoning and that is why they are breathing heavy or gasping air from the surface. Run the 2 filters together will help speed things up.


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## BettaBeats (Jan 14, 2010)

It doesn't matter that it was a well established tank. by putting the new filter on you ran a set up for some time that had no beneficial bacteria to break down ammonia and nitrite. 

plus, lack of gas exchange is a big possibility too.


shucks..


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## dl88dl (Mar 8, 2010)

The Fluval U2 is rated at 105gph and should be enough for a 20gal but since the this filter is not cycled all the live stocks in that tank are faced with very high concentration of ammonia and nitrite/nitrate and will cause the gill membranes to burn and the fishy will suffocate and die. Yes, you can add all the airstone you want...this will only slow the death but adding a cycled filter will correct this poisoning only if the fish's burning has not gone too far.
BTW, if your stocking is on the higher end then I would add an extra filter like AC50 or Hydro sponge filter.


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