Water Stats - What On Earth Is Going On!?

[sumocopter]

Hi folks,
 
I can't get my head around what's going on in my tank - I'm hoping someone in this great font of knowledge might be able to shed some light. 
 
The Tank
Juwel Rio 300, stocked with 10 young discus (6-8 months old), 15 lemon tetra, 10 bronze cory, 4 sailfin plecs (all around 10-12").  I know what you're thinking - overstocked and the plecs will outgrow the tank - if these are the issue I can solve the problem sooner rather than later (I had planned a bigger tank after moving house in which the plecs will fit, but they have had quite an impressive growth spurt since dining out on leftover beef heart!  Four is following rehoming two a friend had, I think we both fell into the 'buy two for £....' at the LFS without doing our research years ago, he gave up altogether shortly afterwards).  Two 12" bubble walls****, filtered by APS 1400, Fluval 205**** and Fluval U4****.  Routine water changes of 30-50% weekly.  Planted, largely java fern and vallisneria, aquatic compost and fine black gravel substrate. No CO2 or ferts.  Lights on 10 hrs a day, no direct sunlight.
 
**** = new addition, see below
 
The Story
Around two weeks ago I removed lots of plant matter - overgrowth and holey leaves - just to tidy it all up a bit.  Half an hour later all the discus were gulping at the top of the water.  I guessed that removing the plants had reduced oxygen generation, but that really was a guess.  So I doubled from one bubble wall to two - and the guys looked happy.  I thought that I would leave everything settle down over night and test the water the following day.  Unfortunately I had got a bit lax on the old water testing but it's been daily since!  Algae has always been a bit of an issue in the tank, this hasn't changed but the plants have definitely grown less recently.
 
The Stats - and this is where I lose all idea of what's going on
pH 7.2, GH 14, KH 5
So these all go date, ammonia, nitrite, nitrate
13/10 - 0.25, 2, 20 - measured, followed by 40% water change (at this point I assumed that overstocking was the issue and added the Fluval filters for extra filtration capacity)
14/10 - 0.25, 1, 10 - followed by WC
15/10 - 0.5, 2, 10 - followed by WC
16/10 - 0.5, 0.5, 5 - followed by WC
18/10 - 0.5, 0.25, 5 - no WC, seemed to be on the right track so I thought I would see how it went
19/10 - 0.5, 0.25, <5 - no WC
21/10 (today) - 0.5, 2, 20
 
I've no idea what's going on!  My one thought is that both the extra filters are taking a while to cycle so are either doing nothing yet or are just kicking out nitrite.  I'd welcome any comments or thoughts, particularly on the nitrite peaks and disappearing nitrate.
 
Sorry for the essay, and thanks for any help!
 
Sumo

 

[Byron]

I may have some insights, but I am not a chemist so not guaranteeing anything.  First, I would have to question the nitrite readings; at 1 ppm nitrite is often fatal, and at 2 ppm you would probably not have live fish.  Though it is still too high.
 
As long as you are seeing ammonia or nitrite above zero, I would suggest daily partial water changes (half the tank) and consider using Prime or Ultimate (these both handle nitrite).
 
It is possible that removing so much plant material removed the capacity to take up considerable ammonia.  Obviously not if the plant matter was just dead, but if live plants/leaves were removed, ammonia uptake would be lessened.  Plants take up ammonia faster than the bacteria, so plants are your prime users of ammonia as this is their preferred form of nitrogen and they also take it up for other uses.  They can use a fair bit, and probably were previously.  Four 12-inch pleco in this sized tank is a major load, and they are obviously significantly contributing to the ammonia. 
 
The reason for the nitrite would then be the Nitrosomonas bacteria increasing to handle the increased ammonia, but it takes much longer for the Nitrospira sp. bacteria to reproduce to handle the sudden increase in nitrite.  Nitrosomonas bacteria can reproduce in approximately 12+ hours, while Nitrospira require up to 32 hours which only starts after nitrite is present.
 
The pH affects the effectiveness of nitrifying bacteria.  They are most effective at a pH of 8.3, and at 7.0 their effectiveness is cut by half.  Temperature is also a factor, but here not a contributing issue for the bacteria.  But another issue is that an ammonia level of 0.7 ppm has been shown to be sufficient to affect the Nitrospira (nitrite oxidizing) bacteria to the extent that they become 50% less effective, and nitrite thus increases.  All of this probably factors in.  Ironically, if the pH fell below 7, you would actually be somewhat better off.  The ammonia becomes ammonium, which is basically harmless, and with the decrease in the ammonia-oxidizing bacteria from the more acidic pH, nitrite is not occurring as much.
 
The gasping at the surface was undoubtedly the nitrite.  Fish readily absorb nitrite from the water and it combines with the hemoglobin in their blood, forming methaemoglobin.  As a consequence, the blood cannot transport oxygen as easily, hence the fish gasp for oxygen.
 
There are bacteria in the substrate that use nitrate; these live primarily in the lower level of the substrate.  With your aquatic compost and depending how long this tank has been running, this could be a factor in the lowering nitrate.  With ammonia so high, sufficient for the plant's uses presumably, I would not expect them to resort to taking up nitrate, as this requires more energy from the plant to change it back to ammonium and they only resort to this when ammonium is below their needs in balance with everything else.
 
Byron.

 

[LilyRose Tank]

Also, the addition of the bubble walls, and a higher level of oxygen in the tank can make any carbon in the tank to be chemically bound to the oxygen, giving off carbon dioxide to the air, leaving less for the plants to utilise. I have been told in the past that O2 walls can be disastrous for a planted tank and this slows the plant growth down. My understanding of this may be very off though as I am a planted tank beginner. But if plant growth slows down, they use less nitrogen and therefore it would be left in the water column?? Not sure but that's my knowledge, sorry if I didn't explain it well, I am sure Byron or someone else will correct me x

 

[sumocopter]

Thanks for the help guys.  I didn't realise how much plants love ammonia!! I thought that nitrate was the main plant food!
 
To continue the story, no water change yesterday (I was thinking along the lines of giving the filters and plants some food to get them going), today Am 0.25, Nitri see pics, Nitra 20.
 
Today's nitrate test, make of these what you will.
- without flash
  - with flash
 
The fish all seem to be happy this evening, I did a 50% water change just after testing.  It seems that I am just in a pickle until the plants or the filters sort it out, I expect that patience is the key.  It all seems like a bit of a vicious circle at the moment, I don't want to stop the bubble walls as I am concerned about nitrite poisoning, with more oxygen plants will recover slower, meaning it will be longer until they take up as much ammonia as before.
 
The next awkward things is that I am off on holiday next week (all these things happen at the least opportune moment), with neighbours arranged to feed the greedy guys but I'm not sure they'd be happy to do large water changes every night.  I have a newly cycled 60l tank awaiting some multis (LilyRose - I've been watching your development with interest

), but that could be given over to the lemon tetras while I am away.  Is it worth moving them to reduce the bioload or could I then have stress issues with the discus as they lose their dither fish?  I have arranged rehoming of one of the plecs, should be sorted after next week if I can catch him.
 
If I've learned one thing - always trim, never deforest!
 
Thanks again for your help.
 
Sumo

 

[Byron]

Previously I offered some insight into possible issues, but I would hope other members with more experience can contribute here.  I have myself never had ammonia or nitrite issues, so can only offer the theory.  I certainly would recommend a conditioner like Prime that detoxifies nitrite (I still cannot believe those high tests...) but this detoxification gives out after 36 or so hours according to Seachem, and then another water change using Prime is needed.  B.

 

[sumocopter]

Thank you once again for your your help Byron. I have always tended to steer clear of chemicals but I will look into Prime now, at least it will give 36 hours relief. I wonder if the fish are coping with the high nitrite just because I am pumping so much oxygen through the water? I did test the mains water from the tap - zero, beautiful blue! I will try with another test kit soon.

 

[DeanoL83]

I unfortunately did a fish-in cycle and my Nitrite tests were just as purple as that for about a week or so. I did 50% water changes every day and added more live plants. After about a week, Ammonia and Nitrite were zero. I lost a couple of guppies before I realised the issue.

Like Byron said, water change every day and use prime. Will get your fish through.

 

[sumocopter]

Hi guys,
 
Just wanted to update you all.  Everything settled down, by Friday evening (24/10) stats were Amm <0.25 (but not quite 0), Nirtri 0, Nitra 5.  Looks like those water changes have done the trick and some bacteria somewhere has caught up.  Thank you all for your help.
 
Cheers
 
Sumo

 

[Byron]

Hi guys,
 
Just wanted to update you all.  Everything settled down, by Friday evening (24/10) stats were Amm <0.25 (but not quite 0), Nirtri 0, Nitra 5.  Looks like those water changes have done the trick and some bacteria somewhere has caught up.  Thank you all for your help.
 
Cheers
 
Sumo

 
Thanks for updating.  I'm glad this was resolved.  B.