Strong current killed my tetras?

[kid4life]

A couple days ago, my current Fluval U3 died so I bought a U4 (was planning on upgrading to a bigger tank soon anyways) to replace the U3.

I put it in, the current was insanely strong but the fish seemed to be okay since they avoided the top area. The next day, I lost a lemon tetra and a cherry shrimp... I quickly removed the U4. I didn't know what to do and had no time to get another filter so i took my old filter, plugged it in and smacked it real hard and it started working again .. so i am back to the U3.. the following day another 3 lemons died.

wth is going on!!! i've had this tank running for a year and half before with no deaths till now

[Tarobot]

did you use the same media from the U3 in the U4?

The U4 has 260gph, and if you have a 47g, that's roughly only 5 times turnover rate which is still ok and though tetras prefer slower water they are good swimmers.

[kid4life]

no i used the new media that came with the U4.. i was thinking that there would be enough benifical bacteria in the tank already with 4 pieces of drift wood and heavily planted tank that it would be okay not to transfer the bio nodes and spounge/carbon .

[Tarobot]

the plants will help a bit but the wood themselves aren't really pored enough to carry much bacteria. i would suggest to add an airstone and use Seachem Stability (you can't rly overdose this product). Bacteria needs oxygen to do the nitrogen conversion cycle and fish also need it to breathe but an airstone will inject air continuously thus satisfying both criterias. Stability is literally bacteria in a bottle.

[gklaw]

I have a U4 as well, you could adjust the flow to come out from the top and bottom nozzle at the same time so the flow will not be so concentrated.

[taureandragon76]

Nothing to do with the flow at all, if you used all new media on the new filter then you don't really have any beneficial bacteria at all and your tank will cycle again. What you need to do is test your water and see what the levels are, I would almost bet that your ammonia and or nitrites are up.

[kid4life]

i read up on seachem stability... since i put my old filter back in with the same media, do you think i would still need it? i know it would've definitely have helped if i used it when i put in the new filter, but now it seems it would be too late..

gklaw: im at work right now and cant test it, but does splitting the output from the top nozzle and bottom nozzle still allow aeration?

[Tarobot]

bacteria dies roughly 20~30mins out of water so chances are it's all gone. can't really go wrong with stability.

[SeaHorse_Fanatic]

As others mentioned, by not reusing the old media, you reset your tank and caused a mini-cycle. Most of the bacteria in our fw tanks live in the filter media, not in the water or on the surface of objects in the tank. Changing out the media completely removed the vast majority of your good bacteria. Now putting the old filter in after its been left dry and not running for a day or two means you're probably adding excess nutrients back into the tank.

In the future, when switching out filters, just take some of the old media and add it into the new filter/media to reseed.

Probably not what you want to hear I'm sure.

Anthony

[kid4life]

ahhhhhhhhhhhhhh 2 more dead cherries and a rummy T_T what an expensive mistake!!!!!

Thanks everyone for the tip everyone !!

well at least this will probably not happen again in the future. lesson learned.