Backyard Aquaponics
A place to discuss aquaponics

55 gal nursery tank...about 13 days old. started with too many fish. Ammonia levels spiked after a few days, and are now down to almost zero... nitrates at 80, nitrites at 2- 5 ppm..I can't tell the difference in the shades of purple. I've salted water, and did 1/3 water change this AM. tested again, and those were the levels. PH is around 7.8. Fish seem fine, tilapia are a hardy lot. I've cut back feed by 50-70%, but was hoping on breeding. Guess I need to be that damn "P" word again....patient. Back to watching my the Bucs get their arses handed to them...again.

Hi Coachchris,
I am a noob to this but with the problems i have had and changes i have had to do i wouldnt worry so much about the nitrates but the ph looks a bit high so your plants wont like it as much and when i found an inbalance in the ph and high nitrates it wasnt till i got the ph back to or close to neutral or 7 that the nitrates changed and the plants fed and grew.

Cheers Frank

Thanks for the reply Frank. The problems not in my AP system, but my new breeder tank for my tilapia.

ok my understanding is nitrates wont hurt the fish and if its a normal tank for breeding you will have to wait for the bacteria to build up in your filter there are some topics on best temps and ph for faster growth so like you posted its a matter of hurry up and wait lol

i was concerned about the Nitrites, hence the water change. Was kind of surprised when a 33% change didn't seem to drop them much. no food, salt and wait...I guess that's my course of action for a while.

yeah i would look at maybe lowering the ph and check amonia as whether you feed or not.

I've read that fish can tolerate a higher nitrite value with a high pH, like a low pH is better with high ammonia.

And if it's a nursery-tank, not a aquaponicssystem I would do maybe a 50% water change to make sure. 50% water change should lower the nitrite level with 50%...

I kept having very high nitrates after my system started up. I just added two new grow beds and they are coming down. You may have too many fish for your grow beds to process the ammonia to nitrates then to nitrates. Also I added two DWC bucket but filled then half way with Lava Rock to get some serious added surface area for bacteria to grow.

Add some pool salt.
1ppt of salt should mitigate against nitrite poisoning.

Don't bother with water changes if it is AP

If this is a breeder tank.. for small fry... then I would be doing water changes...

Fry are much more susceptible to to higher levels of nitrite.. and nitrate.. than more mature fish...