Koi Fish Tank Help

[Aikokoi]

Hello everyone,

New to the community, I haven’t had time to formerly introduce myself yet. My name is Josh,I came onto this site seeking help, my wife and I have 4 small koi fish 3-4in, in a 40 gallon tank.
As for the water filter, I am using an Aqueon Quiet Flow 50. Everything has been fine, in the tank while cycling, we are doing weekly water changes. We are also performing water test, every 2 days (PH, High Ph, Amonia, NO2,NO3 etc..) Temperature in the tank 70F.

Well after 4 weeks, it was time to do a partial water change, as well as change just the filter cartridge. According to the instructions, we rinsed the new filter cartridge under water, and insert it cartridge bio holster. We were sure not to touch, or clean the bio holster or the bio grid.

We added chemicals Api products as normal, 2 days go by and we noticed the water is getting a bit cloudy. And so we tested the water levels, the results where entirely different than normal.

Here are the results: High PH 7.4 | Amnonia 0.25PPM |Nitrite 1.0PPM |Nitrate 40PPM

My wife & I decided to do a 50% water change and re-check the results in 2 days.

Have we done something wrong? A routine water change, followed by filter cartridge itself, shouldn’t cause this radical change I would guess.

Please help us

Thank you for your time
Josh & Janet

 

[fishyfriends3]

Rinsed under water could be the issue. Always clean filters in the water you remove from your tank and not in any other water.

Sent from my GT-I9195 using Aquarium Advice mobile app

 

[threnjen]

Ignore their money grubbing instructions and never ever ever throw out the filter cartridge until it is literally falling apart. You threw out a bunch of your bacteria so now your tank is in cycle.

While you have a new cartridge in there anyway, this might be a good time to replace it with something more useful (their cartridges are pretty sucky). Get a big rectangle of cut-to-fit blue filter foam from the pet store and cut some pieces that fit inside your filter instead of the cartridge.


On a completely other note... but do you have plans in place to move your koi to a pond eventually? These are fish that get up to 3 feet long. They are intended as ornamental pond fish, not aquarium fish.

 

[Aikokoi]

Rinsed under water could be the issue. Always clean filters in the water you remove from your tank and not in any other water.

Sent from my GT-I9195 using Aquarium Advice mobile app

Thank you very much, for your prompt response.
Does this mean we ruined the bio cycle?
And have to start building it up again?

 

[threnjen]

Yes, you are in at least a mini-cycle.
Just don't throw out the filter cartridges, and rise them only in tank water if they are dirty.

 

[Aikokoi]

Ignore their money grubbing instructions and never ever ever throw out the filter cartridge until it is literally falling apart. You threw out a bunch of your bacteria so now your tank is in cycle.

While you have a new cartridge in there anyway, this might be a good time to replace it with something more useful (their cartridges are pretty sucky). Get a big rectangle of cut-to-fit blue filter foam from the pet store and cut some pieces that fit inside your filter instead of the cartridge.


On a completely other note... but do you have plans in place to move your koi to a pond eventually? These are fish that get up to 3 feet long. They are intended as ornamental pond fish, not aquarium fish.

Thank you for that information, for the time being due to small size, they are our in house children. They will graduate over time to the pond.