Dead in a day

[Chill]

Every fish we put in the tank dies in a day!

We cycled it. Ammonia and nitrites are zero. nitrates 10. Ph 7.5. Water temp 72. Water hardness is fine and we add decholrinator. We have 2 air stones, 2 moss balls and one other plant. We have rinsed everything in the tank a thousand times with hot water.

Every test we run our water says it’s fine. The pet stores run a bunch of test they say it’s fine.
But. Every. fish. Dies. IN ABOUT 24-48 HOURS!
We’ve tried goldfish, catfish, and pleco. They’re all super active when we get them and then they quickly slow down and die.

We’ve been trying to do this tank for over a year now and it keeps happening!
Any idea on what is going on?

 

[Delapool]

Same water source as fish store eg not well water or old pipes?

Also no wood or non-aquarium safe ornaments or any rubber or collected rocks / gravel?

 

[1midniterider]

Have you checked for metals or parasites?

 

[Chill]

Everything in the tank is aquarium safe And no wood.
We do use well water. Why would that be bad? I used well water on all my fish tanks growing up and never had this issue.
We have had the metals checked and they were fine. We haven’t checked for parasites how do you do that?

 

[King Fisher]

How do you acclimate them before putting them in your tank? It might be worth running carbon in your filters, if you aren't already, to see if it changes anything.

 

[Chill]

I float them for about 15-20 min then I add a little tank water to the water in the bag let them float another 10 min add a little more water wait 10 more min and then let them into the tank.

 

[shellyx]

Do you buy them from the same place everytime?

 

[V227]

My guess is that water chemistry differences between the fish store water & the OP's well water is causing the fish to go into osmotic shock.
Its probably going to take a slow drip method of acclimation to ensure survival of new fish.

 

[Chill]

We got them from 2 different places. The one store seems to die in about a day the others lasted about a week but then showed the exact same symptoms. They start out super active when we get them home then they slow way down real quick and stick to the bottom of the tank then they stop moving and die.
How long should I do the slow drip to acclimate them? Maybe I could ask if the pet store would test their water and see how far off my tank is from theirs.
I just feel terrible getting these fish and then them dying. I’m trying so hard to do everything right it’s getting more stressful then fun to have this tank):

 

[King Fisher]

What size is the tank?

 

[Chill]

20 gallons

 

[King Fisher]

Maybe try to get an API Master Test Kit and test your water if you haven't already. It's more accurate than strips. I'm wondering if you've lost your cycle and once you add fish your parameters spike.