Nitrite spike

[raymond82]

Hello!
I'm new to this forum, I wanted to introduce myself properly but I ran into an emergency just now.

I'm trying to set up a breeding tank for my A. Nijsseni's and to lower pH and KH I've been experimenting with rainwater and extensive filtering over peat. I have two 30 L containers: in the first one I put rainwater which I filter with activated carbon for at least 48 hours (I also added a small amount of peat to this container). In the second container I mix 2/3 of the filtered rainwater and 1/3 tap water and filter using peat. With this method I get a KH of <3 and pH of ~6-6.5. Perfect Apistogramma water I thought...

After I added this prepared water to my Nijsseni aquarium today I found out that nitrite levels were alarmingly high (in the 1 mg/l range). I checked the other containers and both the tap water/rainwater/peat container and the rainwater/carbon filtering container had similarly high nitrate levels. In the container outside where I collect the rainwater the nitrate levels were low, <0.3 mg/l.

This leads me to conclude that somehow nitrate levels are increased during the filtering using carbon. Has anybody had similar experiences? Or could anyone help me out finding the possible cause? This event sets me back greatly since I thought I finally found a routine to acquire suitable water for my Apistogramma's.

Thank you very much!

 

[wethumbs]

My guess is they are coming from the peat. What kind of peat are you using? It can be the 'enriched' type that has added fertilizer target for plant use.

 

[raymond82]

Thanks for your reply, I've been using two types of peat Sera Super Peat (granules) and Zoobest Black-Peat. Both are meant for aquarium use so I really hope they're not the cause. Today I'm going to start filtering a new batch of rainwater over carbon again (without any peat) and see what happens.

 

[Mike Wise]

I really can't add anything to the discussion. I have just one question. It this a new aquarium? I would expect a mature aquarium with a mature biological filter would quickly remove any NH3 and NO2.

 

[raymond82]

It is a running aquarium with a running filter and there are fish in there already. I didn't want to take any risks however so I immediately changed 50% of the water. Fortunately, my girlfriend keeps a lot of killi's and she always has seperate containers with water treated with water conditioner so I had immediate access to supposedly safe water. Now nitrite levels are down again and the fish behave normally.

Today I did a small test, I put 10 L of rainwater in a container and filtered it using the activated carbon (without any peat) and already after ~8 hours the nitrite levels have raised quite dramatically. I guess this means that somehow the activated carbon is causing the nitrite levels to spike. This puzzles me a little bit, now to complete the test I'll set up a filter with new activated carbon to see what happens.

That brings me to another question: what is the best way to treat rainwater before using it in an aquarium? Would it for instance be safe to use after just treating it with one of these water conditioners?

 

[wethumbs]

If the rain is collected from a shringle roof, chances are you will want to run it through fresh activated carbon filter. You may want to know what kind of shingle it is, some has moss retardant in it which I believe is some sort of copper compound. Even if it has no moss retardant, it is probably an asphalt type shingle which leeches an array of PAH (polycyclic aromatic hydrocarbon) as well as contaminants including heavy metals through time. If the roof is older, it would be safer to collect water from as compare to a brand new roof (less than 1yr old) like in my case. Activated carbon filters contaminants by trapping them in the carbon structure through chemical bonding. Once all these vacant bonding sites are used up, it will start releasing them back into the water as new contaminants exchange with ones that are bonded. Therefore frequent changes of activated carbon filter is important.

 

[raymond82]

That's sounds like a very good explanation. I have been filtering over new activated carbon for almost 24 hours now and I don't see increased nitrite levels. From now on I will regularly check and change my activated carbon. What happened two days ago scared me a lot, now I know that I can continue with my routine to try to make my apsisto's breed.

Thank you very much for your replies. I like this forum a lot, have read a lot of interesting things already and for sure I'll be back with more questions in the future!

 

[wethumbs]

You can now use the nitrite level as a gauge to tell you when to change the activated carbon. You can also get a water flow meter to alert you when to change the filter once you have correlate it to total amount of water flow through the filter which basically determining the life of the filter for your specific application.

 

[dw1305]

Hi all,
What are you measuring the nitrite with? You wouldn't expect rain-water to have any nitrite in it unles you have a very polluted atmosphere with lots of NOx in it. In the UK it has rained fairly heavily lately, with a series of weather fronts sweeping in from the Atlantic, and NOx levels are vitually nil, even in built up areas.

Peat is "peat" because the carbon to nitrogen ratio is extremely low, if it was higher you wouldn't get peat formation, even under anaerobic conditions. You don't really have anything to supply the nitrogen that could form the NO2 and it is more likely that it is interference by chloride ions or similar. There is also the very CEC and AEC of sphagnum peat, which will tend to retain anions like NO2- and exchange them for humic compounds, as well as exchanging metal ions for H+ ions etc.

Unless you have an ion selective electrode? it is fairly unlikely what you are actually measuring is NO2. Despite what you might read etc on fishkeeping forums, it is actually fairly difficult to measure NH3 or NO2 without laboratory grade equipment. The only accurate method of estimating water "pollution" is the 5 day BOD test, and even that is only really an option for labs set up to run it.

If your girlfriend keeps planted tanks could you add some plants? they mainly preferentially uptake both NH3 and NO2 before NO3, and if there really some NO2 they will mop it up until the filter "catches up".

cheers Darrel

 

[raymond82]

We have had (and are still having) a lot of rain here too in the Netherlands (most likely the same storms that hit the UK first). I find myself biking happily through the rain lately only thinking about how nicely my container fills up this way...

I measure nitrite levels with a Tetra test. Most likely it's not too precise but whenever the fluid goes red I do think it's a good indication to change water. I have to say this never happened up to now, all my tanks are planted and I've never seen elevated nitrite levels.

I did test the rainwater again and it's completely free of nitrite (if I can trust the test of course). Since I did a couple of tests I'm pretty sure it must have been the activated carbon that was saturated, as wethumbs suggested. Indeed it's a good indicator for when to change the carbon in the filter, it's good to know I have to be careful with this.

 

[dw1305]

Hi all,
It is still strange, you shouldn't need activated carbon in a planted tank.

I measure nitrite levels with a Tetra test

I think that is an azo dye test, based on the reaction of p-arsanilic acid and nitrite to form diazonium compounds. I can't remember whether you get interference with these or not.

I'd carry on with peat filtered rain-water and plants, I'm still pretty sure this is an anomaly, not a real reading. Most of us routinely change the water even in planted tanks, I change about 10% a day for tanks over 60 litres and more for smaller volume tanks.

cheers Darrel

 

[raymond82]

The nitrite levels I found came from seperate containers that I use to prepare my water before I put it in the aquariums. In the aquariums themselves I've never seen elevated nitrite (except for last week when I added water from a contaminated container), they're all planted and I don't use activated carbon in the filters. In my aquariums I do a weekly 25% water change.

In the mean time the problem has shifted and now I'm starting to think that it might be the peat after all. I have one container filled with rainwater that has been filtering with carbon for two days now and I don't see any nitrite. In the mean time, in another container that has 2/3 tap water, 1/3 rainwater and peat filtration the nitrite levels are up again, comparable to what I saw before.

Maybe in the test I described in post #5 there might have been some residual peat left. In that case it might not have been the saturated carbon but the residual peat that increased the nitrite. I read somewhere in this forum that it might be good to boil the peat before using, I think I'll try that now.

One last question: Through this thread and also others I get the impression that people use pure rainwater in their aquariums, am I correct? Isn't there a risk that with pure rainwater KH is so low that the pH becomes very unstable? So far I've been mixing rainwater with tap water just to prevent that from happening.

 

[dw1305]

Hi all,
Boiling the peat won't make any difference, it is pretty well sterile when it is extracted. The only way you could get much nitrite from the peat itself is if the cation exchange sites were full of ammonium ions (NH4+) that were then microbially converted to NO2-, or the anion exchange sites were saturated with NO2- ions that hadn't been microbially converted to NO3 ions. Naturally the cation exchange sites are filled with H+ ions and the anions sites usually with SO4- or Cl- ions, although AEC is at least an order of magnitude smaller than CEC.

Have a look here: <http://www.apistogramma.com/forum/showthread.php?11247>.

My rain-water has some carbonate content as I live in an area of the UK where both rocks and soil are highly calcareous. People who use RO locally usually cut their RO with ~20% tap (tap is about about 16dKH). A lot of people use peat filtered RO without any addition of buffering for black water fish, although biological filtration will be compromised in very low conductivity water.

Have a look here as well: <http://www.apistogramma.com/forum/showthread.php?12048>
<http://www.sciencedirect.com/science/article/pii/0043135494902917>

cheers Darrel

 

[raymond82]

Thanks again!

The water chemistry is still a struggle for me but slowly I'm getting a hold of it. I'm reading it over and over again now but I think it will take a while before it definitely sits in. Your explanation is very clear though, and I do believe that it's unlikely for the peat to be the source of the nitrite. Just to be sure I just set up another test with new rainwater to see if any of the two peat types I use somehow affects nitrite levels, maybe one of the two is somehow contaminated.

Darrel, another question just came up after reading your last post in the second thread you linked to: if KH is the most important factor, why still filter the rainwater over peat?

The rainwater comes with a low KH here. With a liquid test the color change happens with the first drop and I just checked it with my cheap Ebay-ordered TDS meter and it read 18 ppm (69 ppm after filtering with carbon). So by mixing with tap water I can easily get a KH of 2-3 and then I wouldn't have to worry about pH and peat filtration anymore.

 

[dw1305]

Hi all,

Darrel, another question just came up after reading your last post in the second thread you linked to: if KH is the most important factor, why still filter the rainwater over peat? The rainwater comes with a low KH here. With a liquid test the color change happens with the first drop and I just checked it with my cheap Ebay-ordered TDS meter and it read 18 ppm (69 ppm after filtering with carbon). So by mixing with tap water I can easily get a KH of 2-3 and then I wouldn't have to worry about pH and peat filtration anymore.

I've always used rain-water, but you may find the rain water is less pure in the summer, when you get more dust etc. in the atmosphere. I very rarely test the water, but if I do I just measure the TDS, as long as it is below 150ppm I don't worry too much. I don't keep any black water fish, but if I did I would probably go back to peat filtering to try and remove some of the hardness and get the TDS down.

One reason for peat filtration is to add the humic substances that naturally occur in black waters, and will chelate any heavy metals etc. Whether peat is any better than oak leaves or bark, Indian Almond (Terminalia catappa) or Alder "cones" (Alnus glutinosa/incana/viridis) is open to question.

I like a lot of structure in the tanks (plants, wood, leaves) any-way, so a few more dead leaves isn't going to spoil the view.

cheers Darrel

 

[raymond82]

Today I mixed 1/2 tap water (270 ppm) with 1/2 carbon filtered rainwater (70 ppm) and the pH came out 8-8.5, the KH 5 and the ppm 165. Previously, after peat filtration I would get similar mixes down to pH 6 and KH 1 but I'm a little bit uneasy with peat now.

The test I set up yesterday showed elevated nitrite levels with Sera peat that was in the container with high nitrite before, while I didn't see such an effect with the other brand of peat that was in the same container. I also used new Sera peat from a new box and it didn't show me any nitrite. All these peat tests are probably a bit confusing to read, at least it got me confused quite a bit.

I will be setting up two breeding tanks, one for A. Nijsseni and one for A. Macmasteri. I've seen both of them already do a lot of spawning behavior (never seen fry though) so I expect that giving them their own aquarium will already increase my chances. If it doesn't work I think I will just mix rainwater with tap water and slowly adjust the fish to a ppm of around 150. I'll leave the peat filtering for what it is and just put leaves in the aquarium. We have plenty of oak leaves and catappa leaves already that I could use. I'll keep checking the pH and if needed I could use oak extract to lower the pH, we have a bottle lying around somewhere.