Fluval filter from injured tank

[Familyfishny]

Hi folks,

My sister in law just had an awful die-off in her very old and established tank. It went longer than usual between water changes because she was sick, and when she did change the water she lost all but two of her fish over 24 hours. She is very sad, is shutting down her tank, and has offered me her 2 panda cories who are the sole survivors if we can figure out an intermediate quarantine tank. She has also offered me her Fluval filter, if there’s a way to clean it so whatever killed her fish doesn’t also kill mine.

I really need a better filter for my tank; is there a way to clean a filter well enough to be safe in this situation?

Thanks,all. Any guesses on what happened are also welcome. She swears she did everything the same as usual except for a bigger water change, maybe 30%. Water within a degree F of tank water, conditioned, all the regular things. I don’t have any tank parameters, but the tank was a bit overstocked; her two fancy goldfish got HUGE over the years.

 

[Archerfish]

Whoa, two huge goldfish and a mixture of tropical fish in the same tank? How large is her tank? Yes, you can reuse the filter, but I would completely disinfect it before using again to avoid spreading infection. Disassemble the filter. Clean everything. Then do a Clorox/water soak followed by a complete rinse(s) and a final rinse with a strong dechlorinator. Remember, the new filter will need time to become effective so keep your existing filtration in place until that time.

 

[TNG]

Hi folks,

My sister in law just had an awful die-off in her very old and established tank. It went longer than usual between water changes because she was sick, and when she did change the water she lost all but two of her fish over 24 hours. She is very sad, is shutting down her tank, and has offered me her 2 panda cories who are the sole survivors if we can figure out an intermediate quarantine tank. She has also offered me her Fluval filter, if there’s a way to clean it so whatever killed her fish doesn’t also kill mine.

I really need a better filter for my tank; is there a way to clean a filter well enough to be safe in this situation?

Thanks,all. Any guesses on what happened are also welcome. She swears she did everything the same as usual except for a bigger water change, maybe 30%. Water within a degree F of tank water, conditioned, all the regular things. I don’t have any tank parameters, but the tank was a bit overstocked; her two fancy goldfish got HUGE over the years.

If all that your sister-in-law did was a large change of water then the problem may be what is known as old tank syndrome. Google “old tank syndrome”.

If that’s the case then the filter won’t cause you any problem.

If the 2 panda cories are not showing any sigh of distress, I’d keep them in their current tank for now, together with the filter, heater, etc.

I wouldn’t do any more water change this week, but do a 10% change next week and every week thereafter. I’d only move the cories to a different tank when the pH, GH, ammonia and nitrate of their current tank is roughly the same as the parameters in the tank I’m going to move them into.

 

[GaryE]

Goldfish are deadly killers, worse than piranhas sometimes. Only where the big tetra does it with razor sharp teeth, the goldie does it with poop. They can foul a tank in no time flat. That, rather than temperature and eventual size is why it's suggested to never combine goldies with tropicals. Putting a goldie indoors in a tank is like moving hogs into the kitchen for the winter. The vikings did it, true, but just because it can be done doesn't mean you should ignore the results.

If 30% was a large change, then your sister was losing the tank battle already. I would never keep goldies with Corys, but if I did, I'd change 50% weekly or bi-weekly.

Odds are it was old tank syndrome, and the death of the goldfish saved the Corys. I'd still QT and clean out the filter, because there may have been damage done to the survivors.

 

[Familyfishny]

Whoa, two huge goldfish and a mixture of tropical fish in the same tank? How large is her tank? Yes, you can reuse the filter, but I would completely disinfect it before using again to avoid spreading infection. Disassemble the filter. Clean everything. Then do a Clorox/water soak followed by a complete rinse(s) and a final rinse with a strong dechlorinator. Remember, the new filter will need time to become effective so keep your existing filtration in place until that time.

Thanks, ArcherFish! This was really helpful.

 

[Familyfishny]

Goldfish are deadly killers, worse than piranhas sometimes. Only where the big tetra does it with razor sharp teeth, the goldie does it with poop. They can foul a tank in no time flat. That, rather than temperature and eventual size is why it's suggested to never combine goldies with tropicals. Putting a goldie indoors in a tank is like moving hogs into the kitchen for the winter. The vikings did it, true, but just because it can be done doesn't mean you should ignore the results.

If 30% was a large change, then your sister was losing the tank battle already. I would never keep goldies with Corys, but if I did, I'd change 50% weekly or bi-weekly.

Odds are it was old tank syndrome, and the death of the goldfish saved the Corys. I'd still QT and clean out the filter, because there may have been damage done to the survivors.

Okay, thanks Gary. I was thinking something sudden after a water change seemed like a water issue more than an illness. These were the super fancy-finned, fat, popeyed goldfish; she liked them, but regretted buying them because they had balance and swimming issues. They lived for several years, though.

We will definitely QT and clean the filter; thank you.