Backyard Aquaponics
A place to discuss aquaponics

I'm cycling two tanks one with large goldfish 110 gal stock tank indoors, the other 250 gal outdoor koi pond fishless. My indoor one houses the fish and has the high ammonia problem. I keep doing water changes, 30 gal a day or more and added some potassium carbonate to bring up the PH. Temps are now at 75 degrees The readings with water test stays at 8 or above, PH is 7.2 with 0 nitrites and 0 nitrates. I have a planted growbed of about 50 gal size and an 18 gal bio filter with plenty of aeration in filter and fish tank. My outdoor koi pond is closer to ready with nitrites at .5 and some nitrates starting. The ammonia reading out there is 4. Is it okay to put the already stressed fish outside in koi pond now with the temps much lower (60's) as at least the ammonia is lower and PH is steady at 7.6? I have a bio filter outside and water plants in the koi pond as well as a small water falls and aeration stone. Trying to save these fish as since I've raised the temps to help bacteria growth inside they are showing signs of stress pretty bad. I've not fed in 3 days now and sparingly before that. Surprised the massive water changes aren't bringing down the ammonia. I of course use water conditioner for tap water and have used ammo lock to help detoxify fish tank every other day for this week. Thank you for any answers in whether it's okay to put them in outside koi pond before it's fully ready.

Hi CGmin.

Welcome to the forum.

Sorry about the slow reply, it's just you put up a wall of text, and reading that is like talking for a really long time without taking a breath. So people generally don't read it.

I've never used ammo lock, and don't know much about it, so probably can't help there.

This is an ammonia toxicity chart. You can plot where yours sits.


I'd leave your PH alone for a while, the fish cope with the ammonia better on a lower PH. With the indoor tank, the fish will still produce ammonia through their gills, and I'm curious about how many you've got in there.

With the outdoor pond, the nitrite levels aren't dangerous at the moment, but keep an eye on them, if they get higher with fish, salt to 1ppt to help the fish cope. But measure the temp-PH-ammonia levels out there and decide if you want to move them.

I'd personally move them if they are struggling inside, but that's just me.

Thanks so much for your reply, my apologies for the long winded text. I did move 2 of the 5 goldfish outside to pond and they are still alive! The nitrites are higher out there and I did a 30 gal water change with water conditioner and epsom salt tho I feel the amount was too low on the salt. Will add more today and perhaps more fish. The temps are in the 60's though I have lower ammonia (4) and a starting of nitrates. My ammonia is 8 or above in the indoor tank with only 3 large goldfish and I'm starting to think it's the bio filter for the indoor 110 gal tank that could be the problem. Just cannot figure out why ammonia so high there. It's like I'm over stocked or have a dead fish somewhere but I started with 5 and they are all accounted for. If I move the last 3 outside to pond I have no fish for my plants indoors in the growbed.

So I did a 30 gal water change on both the 110gal indoors with the grow bed and the outdoor 250 gal koi pond. I also removed the biofilter on indoor fish tank tho there is still a reading of 8 ammonia. The koi pond is better with readings but not by much. One of the fish outside, of the two out there, looks bad. Reluctant to add another fish to that pond as I'm not sure if the elevated nitrite levels in koi pond are finally doing them in. On a good note since the nitrites have begun indoors my growth of plants has increased!
110 gal indoor stock tank with growbed (expanded clay) 3 goldfish (7inches).....ph 7.2, ammonia 8, nitrites .25, nitrates 3
250 gal koi pond outdoors 2 goldfish (6 inches).....ph 7.6, ammonia 4, nitrites .5, nitrates 3
Is it okay to use epsom salt for my added salt to help with nitrite toxicity? 1 tablespoon per 5 gal?

No. Don't add epsom salt. It's not the right sort at all. It has it's place, but it's not to help with nitrite.

You want pure salt. Swimming pool salt is usually the cheapest and easiest. Just don't use table salt either unless you know it doesn't have anything else in it (anti caking agent, or iodine). You'll want one gram per litre of water.

Do you have some pictures of the system? How much grow beds you're using? I'm getting the feeling you don't have enough filtration to deal with the goldfish (I thought you had little ones, 7" goldfish are known as koi here).

I'd move them out, it's the ammonia (depending on your water temp) that I'd worry about, salt can help them deal with nitrite spikes (to a limit) easily enough. Make sure your filtration is up to it first though. The fish will produce ammonia without eating.