Nitrite spike and rainbow babies!!

[hollyfish2000]

Heavily planted so need the depth of substrate. (see photo) Neither filter was opened during the cleaning, so the colony in there should have not been disturbed. Very strange.

But Tony to the rescue. 0 nitrite at 2:30 a.m. (yes, I happened to be awake so got up to test. I am nothing if not obsessed.)

 

[Tony]

explosively decompose.

In all seriousness though, I know that a common danger of a deep sand/substrate bed is buildup (and release) of sulfur dioxide gas. This generally only occurs when there is a major buildup of organics down in the sand bed and no oxygen (or plants) to work on breaking it down. I don't think that the substrate on your tank is fine enough (nor devoid of plants) to harbor this condition though. It looked pretty "healthy" to me.

 

[Andrewtfw]

It is possible that when you thuroughly cleaned the gravel, you cleaned an area that had a deep gravel bed and had not been cleaned in some time. This could possibly cause the problem. Honestly, I don't think we will ever know beyond specilation, what the exact cause was. The important thing is that it looks like it is over now and the majority of the fish made it through.

 

[neut]

From what I've read in this thread there are two things to understand here that can explain what's happening.

First is that nitrifying bacteria are quite adhesive to solid objects (filter media, gravel bed, etc.) and simply siphoning the gravel (or sand, etc.) disturbs them very little, if at all. If this wasn't the case, fluidized bed filters would never work because the beneficial bacteria would constantly be knocked off by turbulence faster than they could do any good.

 

[neut]

Second point is that in low to zero oxygen conditions what we normally think of as the nitrogen cycle is more or less reversed. Nitrate is converted first back into nitrite, then into nitrogen gas or ammonia, depending on conditions. So, if you leave a deep enough substrate undisturbed for long enough, all this is going on at lower levels of the substrate and insulated from the water column by the upper level of substrate where oxygen is present and normal nitrification is taking place. In other words it's possible to have a supply of nitrite in your substrate that's normally isolated from the water column.

 

[neut]

(weird, getting a server error when I try to post my complete post, so I'm having to do it piecemeal. So, here's part 3.)

So-- if after the gravel cleaning what you had was an ammonia spike, perhaps accompanied by a bacteria bloom (cloudy tank), I'd say you simply released trapped dirt and nutrients into the water, causing the ammonia spike. But-- since you're detecting nitrite and not ammonia, then probably you directly released the nitrite stored in what effectively was the de-nitrifying area of your substrate.

The sudden and anomalous release of extra nitrite was more than your beneficial bacteria in your filters were prepared to handle since the bacteria colonies grow only to whatever size the available nutrients will support, regardless of how many filters you have going. Thus, a nitrite spike.

From Seachem regarding nitrite production in low oxygen conditions:

There are two types of denitrification that can occur: ammonification and anoxic denitrification. Ammonification results when there is no oxygen and anoxic denitrification results when there is low levels of oxygen. Both result in the conversion of nitrate to nitrite and then eventually into nitrogen gas which can gas off. Ammonification can create ammonia as the final product.

 

[hollyfish2000]

That's interesting. So it wasn't necessarily that the bacterial colony was destroyed, but that nitrite was released from the substrate in amounts that overcame the colony's ability to consume quickly enough.

Does pose the question, though, how does one periodically do a thoroughly cleaning or replanting of a tank without jeopardizing fish. Perhaps you can't?

 

[neut]

...So, just to add a suggestion. If this is repeatedly happening and, because of your planted tank, you're not normally siphoning the substrate, when you do want to siphon the substrate I'd do smaller areas at a time and go ahead and do that area pretty thoroughly. That way you remove rather than release more of what's in there and whatever is released is less of a spike and more of a mild increase that your filters can handle.

If your aim is to clean and redo the whole tank, it may just be a matter of doing a bit at a time with intervals that allow your filters to process the nitrite.

 

[Avatar]

Desirable rogue multipliers

Heavily planted so need the depth of substrate.

Very pretty. I have Amazon swords thriving in 3/4 inches of sand. Do I see a Corydoras in there?

The really great thing about sand besides being kind to Corydoras whiskers and species that like to burrow is that because of the small interstices between packed granules it largely prevents particulates from accumulating in the substrate, and especially if there's some current to sweep everything along toward the filter intakes/sponges. I have 2 40 breeders (Tangs and New World) and virtually everything collects in the corners around the intakes, so much so that when and if I vacuum the gravel there's really nothing there. Means I need to have the siphon in there nearby when I pull the sponges/pre-filters for cleaning but the circular flow pattern in the tanks literally pushes almost all the waste and dead plant matter right into one spot where there also happens to be plenty of water flow and hence oxygen to break down the waste.

Anyway, no sermon intended, just an option going forward.

Have to say I sort of admire all you folks who test your water parameters so religiously. I tested hardness and pH of the tap water when I set up my first tank 2/1/2 years ago and haven't looked at anything beyond temperature since except to confirm that my DI unit was producing pure water. May start playing with and monitoring pH on my Apisto tanks now that everyone is maturing but confess I pretty much rely exclusively/blindly on over filtration and periodic water changes. Don't see that changing unless I get some fancy electric 'multi-probe' that produces instant read-outs.

Anyway Ms. Holly (surely beloved by the animal kingdom), pray don't grieve overmuch or forsake your finned indulgences - after all, you have RAINBOW babies and how cool is that?

 

[hollyfish2000]

Neut -- typically I do a gravel vac when I do my weekly water changes and get the open areas that I can. Not much is open, though. I pulled the tank apart last weekend to catch some fish and do some replanting, and took that opportunity to vacuum areas previously unaccessible (and that needed it). So it was a not usual event. I'll have to be more sensible in the future when doing a big replant.

I like Eco complete's look and assist to the plants. I'm just not a big fan of sand for whatever reason, Sam. Yes, six cories. All made it from what I can tell.

I don't routinely test water parameters unless I think something is wrong i.e. fish gasping or, as in this case, the MTS stuck all around the water line of that tank. Kind of a give-away that something bad was afoot.

 

[Avatar]

Neut--?

Wazzat?

 

[jonclark96]

Wazzat?

He had posted several responses earlier in the thread...

 

[mchambers]

In fact, he/she was posting so many posts and so quickly, I was thinking "neut" stood for "faster than light neutrino."

Anybody got any good neutrino jokes?

 

[neut]

In fact, he/she was posting so many posts and so quickly, I was thinking "neut" stood for "faster than light neutrino."

Anybody got any good neutrino jokes?

Good call.

Neut is my shorthand here for neutrinoman as I'm known on some other forums, though here I keep a lower profile. Relates to my interest in cosmology and physics and what had been one of the big questions in the field, regarding whether or not neutrinos have mass.

 

[neut]

I don't routinely test water parameters unless I think something is wrong

Same here, except for a quick ph check with water changes.

btw-- congrats on the rainbow fry.

 

[Avatar]

Was losing sleep over that myself.

. Relates to my interest in cosmology and physics and what had been one of the big questions in the field, regarding whether or not neutrinos have mass.

And yes for all of you perched on the edge of your seat wondering if his use of past tense means that the question is a question no longer, the answer is yes, neutrinos indeed have mass. But don't worry - I'm bombarded all day every day and I never even flinch. Much.

 

[mchambers]

Neutrino joke:

The bartender says, "We don't serve faster than light neutrinos in here."
A neutrino walks into a bar.

Still wish I understood the source of Holly's nitrite spike. I tend to favor the idea that she stirred up some bad stuff.