Backyard Aquaponics
A place to discuss aquaponics

Hello, its been quite awhile since I have posted, but my system has been quite stable up until about a week ago when I lost a couple fish.

From my water tests it appears that I am having a case of nitrite poisoning, my latest readings are:

PH: 7.2
Ammonia: 0.25
Nitrite: 1
Nitrate: 80

I salted the tank again last week, I think I should be between 1-2 ppt (I don't have any way currently to test it). I am going to do probably a 25%-50% water change today. Is there anything else I can do? My fish are not acting very happy

Also, how do I have a nitrate spike when the ammonia is low and I have a good nitrate reading? I thought that if the ammonia and nitrate were both fine that the nitrite would be taken care of. This tank is almost 2 years old, so it is quite stable.

Also just quick info, this is about a 20 gallon indoor system, so there are no temperature fluctuations or something like that.

Thank You.

do you understand the cycle at all?

Ammonia -> nitrite -> nitrate. so to get rid of nitrate, you need more plants.

sounds like you need more biological growbed volume on the system, and also more plants

Something is causing your ammonia/nitrite spike...

How many fish do you have, how often are you feeding....size of tank, growbed volume.... pumping cycle???

other possible causes of nitrite spiking when the system seems otherwise cycled and stable include...

Anoxic or anaerobic zones actually converting nitrate back to nitrite.

Overfeeding

Solids building up too much

or just simply an over stocked system.

Need some more info about grow bed and fish tank sizes and number of fish and their size in the system.

Amount of flow and aeration and methods the system uses.

Now if you haven't been keeping an eye on the nitrite all along and only checked it when you found dead fish, well it is possible that the fish died of other causes and the dead fish in the system are what caused the nitrite spike you saw.

Remember that salting and then doing a water change will make it even harder to estimate salt concentrations. Before you do the water changes you might make sure you don't have fish poo or uneaten feed building up anywhere in the system, if you do remove it and then do the water change (I only recommend it in that order since the process of removing gunk tends to stir it up.)

And of course, when anything spikes, the general rule is stop feeding till you see improvement.