100% water change - how long before adding koi back in?

[EricV]

We've never heard what kind of filtration is on this 200 gallon stock container. Putting them all back in the main pond could be the best of bad options.

 

[Tula]

I returned the pond water ( only about 150 gallons ) I kept my koi in while the new liner was installed, and tested my water daily.

I wasn't impatient, just felt the water was safe and they were better off in a 1700 gallon pond, than the 150 gallon stock tank.

 

[bettasngoldfish]

As long as the filter is cycled/mature the new pond will be fine with fish in it as soon as the temperatures are matching. Moving old water from the stock tank to the pond is unnecessary.

 

[budgenator]

The concern is the bio-filter will be unable to handle the waste if it is not cycled, if the bio-filter you have on the stock tank is the same filter you'll be using on the pond, then there should be no problem as the stock tank is keeping it in good shape. If that's the case you should move fish into the pond so that their waste will continue to feed the bacteria in the bio-filter.

On the other hand if the bio-filter on the pond has been unused while you changed liners, then it needs to have water ran through it to allow the bacteria to grow and that takes several weeks. Move 1 or 2 of the 6 inchers over to add a little bit of waste for the bacteria to digest. Look for the ammonia level to rise, then fall with a slight rise in nitrites, then you'll know the bio-filter is starting. Then bring over the next 2, and finally the big guys one at a time.

Keeping too many fish in a pond without a cycled filter can harm the fish with surprising rapidity

 

[Alanw]

Thanks, yes it was the same filter, and yes we moved small ones first, then big ones over the next week. Ammonia went up at first, now is acceptable, so it looks like the filters caught up. Haven't turned the uv back on yet tho. Fish are active, eating, and (I suppose) enjoy having 25% more room.

 

[carolinaguy]

Seems like keeping your koi in a small container is more stressful than putting them in safe, fresh water. As said before with ph with .5 and temp within 5 degrees, you should put them back. We have not lost a fish to a dechlorinated freshly conditioned pool in our 15 years. Too successful finding other ways to do them in.