Amonia after substrate change

[KnownToSome]

okay, I’ll try to keep this brief, as I know I tend to over explain!

I have a 29g that’s been cycled, basically unoccupied, and environmentally balanced for 2 years now. The tank was set up for Irrubesco puffers, but now it’s going to be home to a completely different puffer species...with very different needs. The tank was originally well planted (deep rooted anubias, swords, crypts, jungle Val etc) with small grain gravel and large pieces of spider wood for hiding places, It was truly a beautiful little jungle masterpiece! The species that is NOW being accommodated, T. Miurus, could not do well in such environment. They root/burrow very deep in the sand, and even travel under the sand throughout the tank (SOOO cool!). Essentially I had to rip out all my plants, driftwood, and remove all the gravel, and replaced it all with about 4” thick white sand (which made the nastiest mess I have ever seen)! I completed this change of substrate Thurs @ 1:45am (I started at 9pm Weds lol)... and found Amonia registering on my API test kit by Thurs evening! It’s still popping up, when I test. WTH?!? I am familiar with the nitrogen cycle and water chemistry, I knew this would cause a little flux but I expected it to go back to normal by now, as I didn’t change anything with or in the filters.

I really want this under control by Monday when I go pick up my new adoptive finbaby! I’m going to buy some SeaChem stability just in case (to help make sure the levels stay safe) but was hoping for some advice to help get this cycle back where it was. Puffers shouldn’t go into a tank showing even the smallest amount of Amonia or nitrites... any help is greatly appreciated!?!

 

[clownie]

You triggered a mini cycle when you removed all the sand. I think it should settle by Monday since you left the filters intact,there should be enough bacteria in them to get the numbers up again. Good idea to have the stability on hand just in case.

 

[KnownToSome]

Thank you, that’s what I figured happened but tbh was freaking out a little. I know most of the B.B. lives in the filter but I guess more of it was on the substrate and plants than I realized. Oh yea... the plants! ‍That’s it! There were a lot of plants in there, which were in turn helping the water quality and nitrogen cycle... that’s prob got a lot to do with why it’s taking so long to catch back up, there are no plants at all to help now...and with the complete substrate change, class cleaning, and I also rinsed gunk out of the filter media (in tank water of course)- I took out more B.B. than I thought.

On that note, I’m going to go test the water again lol

 

[Gizmo]

There's actually a thing called nitrogen sequestration that happens in freshwater tanks if the substrate goes long enough. The aerobic nitrifying bacteria in your filter converts ammonia>nitrite>nitrate, but there are some anaerobic bacteria that colonize the substrate and convert in reverse, i.e. take nitrate and convert it to ammonia, which is sequestered in the substrate until something/somebody disturbs it.

Even more unsettling, is the anaerobic bacteria can also use sulphate from the tank (used by plants as fertilizer) and convert some of the nitrogen into hydrogen sulfide gas, which can bubble up into your tank and wipe out everything. If you're messing with your gravel and you start smelling rotten eggs, that's the sulphur gassing out of your water.

Plant root systems help mitigate this by naturally aerating the substrate, as does an under-gravel filter, but they're not the cure-all by any means. Any tank that has been sitting for long enough is suspect for sequestration.

Hope I got my facts straight. Feel free to correct me.