Annoying Nitrite spike!!!

I have a 120L tank up and running about 6 months now with 10 Black widows,6 Rummynoses,3 Molly,3 Green cory and 1 Pleco in it.....For the past maybe 4 months i have done 10% weekly water changes(yesterday was latest),gravel vacuum every 3/4 weeks(latest 10/12 days ago),filter clean every 3/4 weeks(latest 4/5 days ago),general cleaning weekly and weekly PH,Ammonia,Nitrite and Nitrate testing(latest yesterday,before i do water change) and all readings for the 4 months have being ZERO and 7-4 PH with temperature at 26.8c!! Apart from 2 Black widows a month ago there have being no additions to the tank but i did have a molly death about 2 weeks ago that i could not explain!!

Fed the fish as normal this morning and all looked fine,came in about an hour ago and they were all gasping at the surface.....checked equipment and all fine,then did water tests and Nitrite was at 2.0 ppm......i immediately did a 50% water change and fish are now looking a little better but i know i'm not out of the woods yet...i will do tests in the morning and 10% water change till it's zero but my question is(sorry about the essay,didn't want to leave anything out)....What could of triggered this spike??? bugging me so it is

Thanks for reading and any help appreciated

Ger

What size filter? How did u clean the filter sponge? Why clean yer filter sponge everytime u do a water change? Maybe increase the water changes from 3-4 weeks to weekly. Mollies and plecs cabn be very messy and maybe the monthly water changes were not enough. Any signs or symptoms on the molly that died?

Thanks Mick but i do weekly water changes and i don't clean me filter every time i change water.....i think i put too much info and too many figures together that i confused your eyes lol.......the filter sponge in cleaned in a basin of the tank water as is the whole filter........the molly had no signs of illness at all,had her 6 months and one morning i looked in and she was in a ball at the bottom of the tank..put her in a breeding tank for a closer look but no marks of any kind...10 minutes later she was dead.....all tests were ok

ger

Sorry for bumping this people but could really do with a bit of help.......as from the first post,i can't see what i did wrong,but i did a nitrite test just now and it's gone up to 5.0 ppm and above......alarm bells are ringing so any suggestions are really appreciated......did a 25% water change just now and i haven't fed them yet,maybe not feed them for a couple of days??

thanks,ger

Ger, here's a recent thread that was opened not so long ago. I'd suggest you read it a few times if your chemistry is as bad as mine! It makes good sense though.

www.irishfishkeepers.com/index.php/fforu...-rise-question#10318

I'd suggest you do 25% daily water changes until your readings come down to zero. Also if you can get your hands on the 'Prime' brand water conditioner and use it at 5 times the recommended dosage on the bottle it will detoxify the nitrite present even though you will still get a reading of nitrite on your test kit. This will obviously help your fish immensely while your bacterial colonies get back up to speed. Reducing feeding will also help.

Dave

Thanks for the reply Dave,yeh read that thread yesterday...ians threads are always very imformative even if i do have to google a lot of the words lol.......i'm going to put it down one of those things i dont understand even as you said Ians words make sense(dont think i'm making sense though),the chemistry end is beyond me........Its just after a while yeh get attached to the little gits and you hate to think there was something you didn't know that could of helped!!
i'll keep up the daily changes until i get it down to zero and maybe feed them every other day.....i have added 'prime' conditioner but not the amount that you suggested so i will add more!!

Thanks again Dave,much appreciated

Ger

Having to google the words I use????
My ex- used to give out to me saying that she needed a dictionary to be able to follow my songs.

If you have a 2ppm nitrite reading then even a 75% water change would just about bring the level to the maximum acceptable for fish (some fish may take higher than 0.5ppm, but generally you need a level much lower than that).

But, and there is always a 'but', the high nitrite may have already done permanent damage:
in some cases that permanent damage is not fatal, but in others it may be acutely fatal within days (even if you do manage to reduce the nitrite levels).

I would usually always question a test kit as standard routine.
If there is no obvious problems, then the test kit may be at fault.
But if you are losing fish or they are showing signs of illness then something is wrong (irrespective of the test kit).

In an ideal world (ie one that exists that in a text book but not in any real situation), your system is supposed to go from ammonia to nitrites to nitrates (ie the 'standard' cycle route).

So long as nothing goes wrong in a tank, then why question the 'text-book' cycle route (the text book is wrong, but it doesn't matter if everything is OK).

Where you would probably find problems is trying to explain what happens in real life if something goes wrong.

Typically we often seen nitrite spikes in:
a recently set-up tank; or
one that has had potent medication; or
a filter system failure (caused by poisoning, poor cleaning, or power failure etc)

But, you can end up with a nitrite spike or an ammonia spike even in a 'cycled' tank (but I don't like that word anyway) even if you do clean your filters properly and have no failure of filters.

In a classical text book scenario, you get
Ammonia > nitrites
Nitrites > nitrates
Nitrates > diluted by water changes, or removed by plants, or you may have some denitrification turning the nitrates to nitrogen gas (by bacteria under anaerobic conditions).

BUT...in the real fish tank, you get the above plus the following under certain conditions:
Ammonia + Nitrite > Nitrogen Gas (this is called Anaerobic Ammonia Oxidation)
Nitrites > Ammonia
Nitrates > Nitrites (and then to ammonia)
Nitrates > Nitrous Oxide (and some other nitrogen gases)
Nitrates > nitrogen gas (eg catalyed by managanese...this is called 'chemodenitrification')
Ammonia > nitrogen gas (eg catalysed by permanganate in the water....this is 'chemoxidation')
and
Nitrite > Nitrogen gas (by something called 'Oxygen-Limited Autotrophic Nitrification-Denitrification').

Part of the normal process of bacterial denitrification can be interrupted and that would release nitrites.

So....apart from a few more words to google, the system is not easy. It is only when something goes wrong that these complexities come into play.

ian

Forgot to mention....methylene blue (one of my thumbs-up compounds).

It is an antidote to some, but not all, poisoning effects of nitrites and nitrates.

ian

Jaysus nice one Ian,as always,very helpful and of course very educational,both to me and google!!
You wrote about typical Nitrite spikes in new set-ups,potent medication and filter system failure,but 'i think' none of the above applies to me.....after that you lost me a bit in Chemistry,but i kinda know were you were going so thanks.......Hopefully i will get the Nitrite down to zero real soon and there is no major damage to the fish,here's hoping!!
And thanks for mentioning Methylene blue,i just googled it(doing a lot of googling lately)and it gets the'thumbs up' from many hobbiests so that will be purchased tomorrow!!

Thanks very much Ian,i never thought the day would come when i'm interested to know what a word like 'chemodenitrification' means....yes yes google has being a very busy little bee!!

Cheers man,Ger

Cheers Ger.

There is not too much chemistry in the above reply.
But it should show that things are not as simple as is often thought.

On names and terms....the reaction where nitrite is converted to nitrogen gas:
Nitrite > Nitrogen gas (by something called 'Oxygen-Limited Autotrophic Nitrification-Denitrification').

has been give a pet-name: OLANDO....."oxygen-limited.." blah blah.... I'm sure that who ever came up with that name probably more interested in coining a new term than in explaining the science

The bottom line on the few reactions I mentioned is that even if you have a 'fully mature and cycled tank' that suddenly there is a potential for the system to go into reverse.

at the the start you get ammonia (max 0.02ppm for the toughest fish)....that 0.02ppm may get converted to nitrite (and here the tough fish could tolerate 0.5ppm)...then that gets converted to nitrates (and tough fish could tolerate 90ppm).

SO....you could have a tank with, say 20ppm of nitrate and many fish may be OK.....but if suddenly some of that starts to get converted in reverse to nitrites then you have the potential of much of that 20ppm of nitrates being converted to nitrites: and the concentration of nitrites would be much higher than you'd ever get from the initial ammonia to nitrite route.

A few pictures and diagrams are the best way to explain the chemistry though.

Somewhere in my original reply here is the answer to what has happened in your tank (unless you have introduced pure nitrite salt from the chemists)....but which one exactly is not easy to tell without a complete history and analysis of the tank.

ian