Wierd Nitrate Spike, Cant explain or control. Any Help please - Tropical Fish Keeping - Aquarium fish care and resources
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post #1 of 5 Old 10-02-2012, 03:20 AM Thread Starter
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Wierd Nitrate Spike, Cant explain or control. Any Help please

Hi All, Im a newbie and after many hours of net research, my mind is all screwed up. Any assistance would be great.
A brief history of the tank. Fishless cycle conducted for two weeks. Added plants and fertiliser for a further two weeks until established and growth observed. Cycle was complete with all parameters returning to zero.
Began adding fish until current occupants. (2 per week). Had a few losses to mouth fungus. And due to mis-information from the aquarium I believe I am overstocked. GRRRR
Hair Algae outbreak. Controlled with reduced fertilzer and plant trimming. (Three month mark)
PH Issue (four month mark....dropping from 7.2 to 6.0. Now stable at 6.8 for last two months)
Current Parameters
PH 6.8
A 0ppm
NO2 0ppm
NO3 40ppm (Currently conducting daily water changes 10-15% to maintain levels. But i cant seem to reduce it)

I was doing water changes (25% weekly), Filter rinse in tank water and gravel cleaning. I just cant explain the spike as the plants are still growing. Minus the few nibbles from a particular tetra.

Any help would be appreciated


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post #2 of 5 Old 10-02-2012, 06:34 AM
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Well, overstocked tank,plus fish food's,plus fish waste(poop), could be contributer to elevated NitrAtes.
Could add more plant's that readily consume nitrates,reduce stock,reduce feeding's.
Might also check tapwater, or source water for nitrates.
If pH is stable ,,I would not worry bout it unless keeping fish that do best in hard water.
Weekly water changes usually help maintain stable pH.

The most important medication in your fish medicine cabinet is.. Clean water.
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post #3 of 5 Old 10-02-2012, 07:30 AM
First, you should test your source water. I have a country well and the nitrates in my well water are off the chart. I have tested nearby municipal water and found it to be 20ppm+. So if your source nitrates are high, modest water changes to reduce tank nitrates becomes very difficult.
Otherwise, 1077 is correct. High nitrates is the backside of the nitrogen cycle and short of a de-nitrate filter, fish, fish food, fish waste, plant fertilizer are all nitrogenous producers resulting in nitrate.
You might 1) add more plants; 2) cut back on feeding*; 3) increase weekly water changes to 50%; 4) reduce stock level.

*note: Fish are 'programmed' to eat whenever food is available to survive times when food is scarce. Much like humans, they will overeat and more food in means more waste out...and some uneaten food.

Until a tank is established and there is a bacterial balance, fungus can be an issue and some fish are more susceptible than others. I had a fungus problem with Mollies in the early cycle stages of my 60g.

On the 'up' side, it would appear your nitrosomonas/nitrospira and nitrobacter beneficial colonies are well established to handle the ammonia and nitrites.

Footnote: With such high nitrates in my source water I use deionized (DI) and rain water (treated for minerals and pH) for water changes and continue to explore means to keep tank nitrates low and encourage development of anaerobic bacteria to convert nitrates into nitrogen gas.

Good luck - keep us posted.


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post #4 of 5 Old 10-02-2012, 12:32 PM
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If this is the 9 gallon tank in your Aquarium Log, it is too heavily stocked. You need to consider removing some of those fish. Also, you have fish that are shoaling, meaning they must be in a group. But there is no room for any of these as it is, so you have some decisions to make.

The fish you have are in our profiles, under the second tab from the left in the blue bar across the top of the page. Each profile contains minimum number of fish, minimum tank size for that number, and any other issues. Please have a read. We're all here to answer any questions.


Byron Hosking, BMus, MA
Vancouver, BC, Canada

The aquarist is one who must learn the ways of the biologist, the chemist, and the veterinarian. [unknown source]

Something we all need to remember: The fish you've acquired was quite happy not being owned by you, minding its own business. If you’re going to take it under your wing then you’re responsible for it. Every aspect of its life is under your control, from water quality and temperature to swimming space. [Nathan Hill in PFK]
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post #5 of 5 Old 10-03-2012, 03:06 AM Thread Starter
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Thanks for the help. Tested the tap water after first noticing the spike two weeks ago. Was indicating 0ppm for nitrates. And definately understand about the over population problem ( beginner mistake) and trust in the aquarium info. The Buanos aires terta (eating my plants) will be making a visit to the aquarium free to a new home to take some of the stress of the plants and tank as he/she is the biggest.
I have halved the current feeding amount which was based on the two minute rule (Enough to keep them feeding for two minutes) which i read somewhere.
The real issue was that given the current population i didnt have any readings after the tank cycled and added the fish in small amounts, the readings were all 0ppm for A, NO2 and NO3 for roughly two and a half months. Then the spike just appeared and wont go away.
Will keep you informed of the progress to reduce the spike.


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