seeding a 40 gallon

[FreshwaterHawaii]

Also my clown loaches look a little whiter than usual so i can tell they're stressed. I tried putting in prime without doing a water change but im not sure if that did anything...Not sure about what else i could do to keep them less stressed.

 

[calioutlaw1a]

What should I do if there's a lot of nitrites, ammonia, or both? Do I do a water change? Or use prime?

Do a water change and use prime.

Some clown loaches and maybe a couple tinfoil barbs. So if you moved established filter media from one tank to another, the new tank is automatically cycled?

Yes, but you can't be sure how much the established media can handle. As long as you keep an eye on ammonia/nitrite/nitrate you should be fine.

I always heard that taking water from a established tank wont do anything because the beneficial bacteria doesn't live in the water itself? I could have read it wrong, not sure. thanks for all the replies, its helped a lot. A little update... So i did take some of the ceramic cylinders from my 125 gallon filters and put them into the penguin 350 i had on my 40g. I tested the water the next day and the ammonia dropped a little and nitrites began to rise. I then tested nitrates and it came back positive for nitrates which is a good thing. Now im just waiting for ammonia and nitrites to drop to zero...hopefully it wont be long.

Correct, taking water from one tank and adding it to another will have little effect on the beneficial bacteria because they colonize the surfaces of everything in the aquarium. This is the reason we use biological media with a large surface area, so they have more room to proliferate.
Your plan sounds good.

Also my clown loaches look a little whiter than usual so i can tell they're stressed. I tried putting in prime without doing a water change but im not sure if that did anything...Not sure about what else i could do to keep them less stressed.

Stressed from what? I would just leave them be as much as possible now and after adding them to the new tank.