Nitrites won't drop to 0

[Maurice2]

My tank is 4 months old now and my nitrites won't quite drop to 0.
For over a month they're hovering at 0.05ppm - not a lot but it's telling me something isn't quite right. All other parameters are perfect.

I've verified the testkit with tap and RO water, it indicates 0.0 correctly for both.

I've used a bacteria spray bought from the LFS, no no avail.

Tank is 480L, wet/dry sump with sponge+bioballs and I have an Eheim canister mechanical filter to remove debris in suspension.

Population is snails, hermits, shrimps etc, a cleaner goby and a lawnmower blenny - no other fish.

I know things don't happen fast but I'd like to get perfect conditions before adding decorative fish.

Anyone have an idea how I could enhance my bacteria?

 

[fishfreek]

Are you certin that you have a saltwater nitrite kit? Do you have a LFS that you can take your water sample to and have check it aswell?

 

[Maurice2]

Are you certin that you have a saltwater nitrite kit? Do you have a LFS that you can take your water sample to and have check it aswell?

Yes and yes. AFAIK their test kit is the same as mine, JBL is a German company and their test kits are universally recognised here in Europe as very reliable.

I've *never* seen nitrites completely at zero and I'm stumped as to what avenue I should explore...

 

[tecwzrd]

Using a canister, sponge, and bio-balls will all trap waste which will keep your no3 level somewhat high. All need to be cleaned regularly to keep waste down which leads to no3.

Do you use a skimmer? Also having the slight readings you have is not that bad.

 

[Brenden]

.05 is nothing to worry about. I had a slight reading also until my fuge was going good. If it bothers you set up a fuge. Plus as your tank gets a little older it will probably get lower unless your bio-load is heavy.

 

[Maurice2]

Using a canister, sponge, and bio-balls will all trap waste which will keep your no3 level somewhat high. All need to be cleaned regularly to keep waste down which leads to no3.

Erm, but it's nitrite (NO2) which is bothering me, not nitrate (NO3), or have I mis-understood something?

Do you use a skimmer?

I think so. A picture is worth a 1000 words. Looking upwards inside the tank:

and looking downwards from above:

My concept of skimmer = yours?

.05 is nothing to worry about. I had a slight reading also until my fuge was going good. If it bothers you set up a fuge.

Agreed, but 0.05 is not 0.00, which suggests to me that something is still slightly amiss.
I've seen the term "fuge" a lot on this forum, in particular when breeding "pods" to feed mandarins. I'm presuming "fuge" is some kind of protected place where one breeds inverts ("pods"?) to feed one's fish. (In my ignorance I bought a psychdelic mandarin, watched it starve to death and had pangs of guilt.)

Could someone enlighten me on the art of "fuges"?

Sorry to be such a pain with all my noob questions, local LFSs are hopeless for advice...

 

[Brenden]

My fault. I only read up as far as tecwzrds post. He talks about NO3 but just now I read up to your original post. In short I am blaming it on tecwzrd NO2 levels of anything other than 0 is a problem. It probably has to do with substrate and the amount you feed. What type substrate do you have? The term fuge gets used several ways on here. A true refugium is a tank preferable around 20% or more the volume of the main. It has a low current as its purpose is to grow macro which removes NO3, PO4, etc from the water. Because it is a protected environment pods grow like crazy in it. The small HOB "fuge" sometimes referred to on here is not a true refugium IMO. It is just a place as you described to grow pods. Unless they are around 20% of water volume there is not enough macro to do much good for the tank.

 

[tecwzrd]

Erm, but it's nitrite (NO2) which is bothering me, not nitrate (NO3), or have I mis-understood something?

No, I should have been clearer. Anything that traps waste will lead to higher levels of nh3 which converts to no2 and then no3. If properly feeding then it shouldn’t be that much of an issue as Brenden pointed out.

Fish/inverts will tolerate the .05 ppm no2 level for short time periods ie: a death in the tank that causes the small spike for a day or two but if you have had this level constantly for 4+ months then too much nh3 is being introduced to the tank through too many fish introduced at one time and/or too much feeding. Your bacterial base should have compensated for the increased nh3 load by now.

Could be the test kit is off since it’s highly unusual for you to still have no2 readings at this point. Do you and the lfs use the same test? Have you tried another type of test? Do you ever get readings of nh3 or is that 0?

This is what I meant by skimmer:

 

[AMANIQU77]

It is weird that you don't have denitrifying bacteria in your tank. If your ammonia constantly stays at 0, then there's a very very big possibility that your nitrite may shoot at zero as well. It would be the Nitrate factor that you will end up worrying with from a overstocked bioload.

Your setup, however, seems perfect. Very low bioload, clean and clear crisp water, your pH shouldn't affect your nitrite directly...So I don't really know why you don't have denitrifying bacteria that shoots your nitrite to zero.

That's puzzling. Four months is a lot of time and it should've cycled by now. Normally, nitrites are zero. Don't add anything. Just wait. denitrifying bacteria has to form whether or you make an effort or not as long as you have a bioload that provides ammonia in your tank.

Good luck.

 

[Maurice2]

This is what I meant by skimmer:

Ah, a protein skimmer, not a "physical skimmer", we weren't on the same wavelength. No, I don't have a protein skimmer and I don't think that I need one, at least for the moment.

It is weird that you don't have denitrifying bacteria in your tank. If your ammonia constantly stays at 0, then there's a very very big possibility that your nitrite may shoot at zero as well. It would be the Nitrate factor that you will end up worrying with from a overstocked bioload.

Your setup, however, seems perfect. Very low bioload, clean and clear crisp water, your pH shouldn't affect your nitrite directly...So I don't really know why you don't have denitrifying bacteria that shoots your nitrite to zero.

That's puzzling. Four months is a lot of time and it should've cycled by now. Normally, nitrites are zero. Don't add anything. Just wait. denitrifying bacteria has to form whether or you make an effort or not as long as you have a bioload that provides ammonia in your tank.

Good luck.

Thank you, essentially the same logic that I went through, my bioload is infinitesimal (two fish, a few shrimps, etc in 480L) and there is logically no reason after 4 months why there could be any nitrites left. I'll take some water to the LFS to confirm, but I'm 99% sure what the result will be (the same).

This is bothering me and I'm not going to add anything until I'm certain that everything is spot on.

Proposition: Deliberately add a fresh (dead) shrimp and let it decompose to see how the NH3/NO2/NO3 evolves? Yea/Nay?