Nitrites Spike every water change - Any help would be amazing!

[SilverB]

Hi Friends
I'm new to the forum, and excuse me please for skipping out on the introduction, but I've got a bit of an urgent problem I really need some help with. If you could read through and give me some advice, I'd truly appreciate it.
First, I'll cut to the facts of my set-up:

• Tank - 21 Litre Aqua One nano
• Age: 1 year 2 months (but the set up was completely re-done in December 2019 - filter media was kept and tank cycled again)
• Set up type: Freshwater planted kept at 25 degrees Celsius
• Livestock: 1 Betta fish, 1 Amano Shrimp
• Light schedule: 8 hours normally (currently running 4 hours on, 4 hours off, 4 hours on due to algae -see below)
• I don't have an air stone or air pump and the tank pump is on low (as the betta doesn't like strong water flow)

I've had a lot of ups and downs with this tank - its been my first planted and heated set-up and honestly I've gone through all the issues. The only thing I managed to get right was the initial cycle of the tank!

At the moment I'm running two problems and I don't know if they are related.

I've got a major problem with Cyano bacteria, green algae (I believe its cyano as its slimy and covers everything in a sheet which comes away easily). My source water is high on phosphates and I've made the decision to soon move to RO water instead of tap. But I can't make this change for a few weeks for a couple of reasons that I won't go into right now.

The biggest and seemingly inexplicable challenge I have is that every time I do my weekly water change (between 35%-50%), within a few hours (most notably if the light is off) the Nitrites spike. Sometimes the level is low-ish (0.25 ppm) and recovers over night, and sometimes it gets as high as 1.0 ppm. Keeping the light on and letting the plants do their thing, helps immensely.

This is what is happening this morning. I did a smaller water change (about 15%) to try and dilute the Nitrites which were around 1.0 ppm, but they're spiking even more since (2.0 ppm). I don't have a secondary tank to put my livestock in so I've filled a large storage container with water (decholorinated) and placed them there while the tank cycles these readings out (doing daily water changes to keep things okay for them). Usually within a couple of days, the nitrates go back to 0 ppm. Key note - Ammonia is sitting always at 0. It does not increase at all during any of these spikes.

Measures I've taken:

• I always use dechlorinator before adding fresh water - I used to add the dechlorinator and then immediately put the water in the tank, but my local aquatic shop told me it actually takes ten minutes to work (I had no idea, its not on any product packaging!) - so now I'm leaving it for 10 minutes - but this doesn't seem to have solved the issue (note that the immediacy of adding the water didn't seem to impact the tank before
• I wash my filter media maybe every 2-3 weeks, in the tank water I've removed, and I do it gently
• I add either API Stress Zyme or Pure Aquarium balls to the tank with every water change
• I match the temperature of the water to the tank before adding
• I do vacuum the gravel but the algae is making this a challenge, since it coats everything
• I remove dead/dying leaves during weekly maintenance

The only other thing is I don't have much space, so I only have one bowl which I can use to capture water from the tank, and have to use the same bowl to add water back in - so I can't be dechlorinating water at the same time as removing water - however, whilst I'm waiting for the 10 minutes, the filter media is still beneath water - so not drying out.

Somewhere, my bacteria is getting knocked back, and I don't know how. I feel like I'm doing all of the right things (to my knowledge and advice from my Aquatic store), but honestly, I'm getting so frustrated and worried for my livestock.

Its been a bit of an uphill battle, I've had fin-rot, snails, shrimps lost to the filter, brown algae, green algae, swim bladder issues...I really want to enjoy the hobby and learn how to craft a maintain a beautiful tank, but honest to goodness this is sapping the joy out of it for me a bit!

If you have any experience with this, or any issues in what I'm doing that could explain what's happening, I'd be really very grateful!! Let me know if more information is needed - I've tried to be as detailed as possible on the set-up

Many thanks!

 

[PheonixKingZ]

@essjay has considerable knowledge in water chemistry. Hope she can help.

 

[SilverB]

As an update this morning, the nitrites are now at 0 ppm - I'm not sure how long on average it takes nitrite specific bacteria to recover, but they seem to recover quite quickly when this happens - I've had occasions in the past where the tank had to be completely cycled again to recover.

 

[Essjay]

It does seem odd to have nitrite spikes but no ammonia spikes. It sounds as though something affected the bacteria colonies.

I have found this in a post by TwoTankAmin, who did a lot of research into these bacteria and cycling

The minimum doubling time for the ammonia oxidizers is as slow as molasses in terms of most bacteria (they can double in minutes). However, under optimal conditions, tank bacteria can double in about 8 hours but it can be as long as about 11 hours. The nitrite oxidizers need at least 12 hours in optimal condition to double. This is why when cycling a tank the ammonia levels get to 0 in fewer days than nitrite levels will do so.

If something had damaged all the bacteria, the ammonia eaters would have recovered faster than than the nitrite eaters, a pssoble explanation for the nitrite spike without an ammonia apsike - the ammonia spike happened between one test and the next so you missed it.

 

[PheonixKingZ]

As an update this morning, the nitrites are now at 0 ppm - I'm not sure how long on average it takes nitrite specific bacteria to recover, but they seem to recover quite quickly when this happens - I've had occasions in the past where the tank had to be completely cycled again to recover.

Thats great news!