Nitrites not going down? - The Planted Tank Forum
LinkBack Thread Tools Display Modes
post #1 of 5 (permalink) Old 04-11-2019, 05:21 PM Thread Starter
Algae Grower
PTrader: (0/0%)
Join Date: Nov 2018
Posts: 10
Nitrites not going down?

I have a new tank I'm setting up and has been cycling for about six weeks. The first month, I just had it cycling within the sump while I did a dry start on the display tank. About two weeks ago, I flooded the display tank and the whole thing is currently running together.

The ammonia is dropping quite nicely and hovers around 0.25ppm which as I understand, sometimes the test kit will register that as zero. I'm having a little bit of algae problems which I think may be contributing to a slightly green tint. I can dose up to 2ppm and it'll drop down within a 24 hours so I believe the ammonia eating bacteria is in great shape.

The nitrites are another thing. The levels will come up to 5ppm but will stay there. The nitrate level has increased as time has gone on so there must be some nitrite eating bacteria growing but the nitrite level never goes down to zero. I've read about stalled cycles and they recommend a massive water change, so I did a roughly 80% change but it still seems to be stalling. Perhaps I'm just being impatient? It's also possible I'm just increasing the nitrite levels too high as I keep dosing a bit of ammonia to keep those bacteria happy.

Any thoughts?
redearedslider5 is offline  
Sponsored Links
post #2 of 5 (permalink) Old 04-11-2019, 11:15 PM
Wannabe Guru
AbbeysDad's Avatar
PTrader: (0/0%)
Join Date: Apr 2016
Location: Central New York, USA
Posts: 1,318
At certain levels, the ammonia and nitrite are toxic to the very bacteria that we need to convert them. Cut back on the ammonia added and do regular water changes.
What are your tank.filter details and what are you using for bio-media?

Tank On, Mike-
60g Marineland Community, Finnex Planted+ 24/7, Silica (pool filter) sand.
10g, 29g, & 37g fry grow out tanks, 110g stock tank.

What came first, the chicken or the egg. It was the egg, but not the egg from a chicken.

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
AbbeysDad is online now  
post #3 of 5 (permalink) Old 04-12-2019, 02:23 AM
Planted Member
PTrader: (0/0%)
Join Date: Aug 2018
Posts: 244
I've had the nitrite-portion of cycles stall before when it seemed like the bacteria that converts ammonia to nitrite quickly grew and converted all of the ammonia. This is a well-known issue. For example, I believe the instructions for the Dr. Tim's bacteria in a bottle advises you to do a water change if the nitrite rises above 5 ppm because the cycle will stall. It's happened to me on about half of my cycles. The water change has always seemed to resolved it, and then the tank fully cycled within a reasonably short time thereafter.
AcidGambit is online now  
post #4 of 5 (permalink) Old 04-12-2019, 02:49 AM
Planted Tank Enthusiast
Jamo33's Avatar
PTrader: (0/0%)
Join Date: Feb 2014
Location: Florida
Posts: 661
I was just reading about this and don't want to start a debate, but what I've read thus far is that cycle will not stall from nitrite excess. Ammonia, yes. But not nitrite.
As you dose more ammonia, you create more nitrite each time. Sometime like 4ppm ammonia creates 11.2ppm nitrite. So each day you add more and more. The bacteria that changes nitrite to nitrate has not yet grown enough, so it will continue to rise until. Boom. All nitrite disappears as the exponential growth of the final bacteria changes nitrite to nitrate. So, when we do a big water change and radically reduce the amount of nitrite in the water, and then suddenly it cycles, this isnt because it has stalled. Rather it is because the bacteria now has far less nitrite to eat through.
But then again...I do the water change and the tank cycles as I dont know what I believe.

Either plug on and wait. Or water change and you'll probably see some fast changes. Also, water change should be done simply for the mineral replenish.
Good luck!

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Jamo33 is offline  
post #5 of 5 (permalink) Old 04-12-2019, 06:53 PM Thread Starter
Algae Grower
PTrader: (0/0%)
Join Date: Nov 2018
Posts: 10
The display tank is 21 gallon going to a 10 gallon sump. The sump has 1 kg of Fluval Biomax rings for the biological filter section.

So the path forward seems to be to keep dosing ammonia and do daily water changes to manage the resultant rising nitrite levels? What sort of percentage do you think?
redearedslider5 is offline  


Quick Reply

Register Now

In order to be able to post messages on the The Planted Tank Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:


Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode

Similar Threads
Thread Thread Starter Forum Replies Last Post
Guide to Starting a Freshwater Aquarium (including Planted Tanks) librarygirl General Planted Tank Discussion 14 10-10-2019 08:10 PM
Tank Cycling, Nitrites in rebellion. Cynglen Fertilizers and Water Parameters 2 04-06-2016 11:52 PM
week one..I have nitrites..Am I o.k? manford Planted Nano Tanks 7 09-24-2015 11:55 PM
...can't get nitrites to show up UPDATE, now I can't get nitrites DOWN! ravensgate Shrimp & Other Invertebrates 34 08-30-2012 04:51 PM
A puzzle: Does Seachem Stability reduce nitrates (yes, nitrates, not nitrites) aadro General Planted Tank Discussion 3 08-28-2012 05:23 PM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome