How Can I Lower The Level Of Nitrate?

[ey2006]

Hi, I was wondering if Nitrates could be reduced in any way?

I have a 240L FW tropical tank, its been up and running for almost a month (has completed cycling) and is moderately planted.

Water stats are:

Ammonia 0
Nitrite 0
Nitrate 40-80ppm (not 100% sure as its hard to read the Nitrate readings on the test results card)
PH 6.8

When would nitrates start becoming lethal for the fish? Is 40-80ppm still ok? I know its best to have Nitrates at 5-20ppm, but what level is unacceptable for fish?

The nitrate levels were at 10-20ppm a week ago, not sure why its peaked, since I haven't introduced any new fish or plants to the tank.

Any advice would be appreciated. Cheers.

 

[Bloo]

You need to find out what your tapwater levels are - let a sample stand for 24 hours and then test.

If you have excess nitrate in your tank, but a low tap nitrate, then the only thing that will help is to reduce stocking levels or perform more/larger water changes more often.

Where I am, it comes out of the tap at pretty much 40ppm. I'd say anything above 50ppm long term is not good for the fish. Adding plants will help to use nitrate and reduce levels.

 

[andywg]

The general guide is that so long as your fish are not very sensative (read rays et al) then under 100 ppm is ok. Ideally you want to aim as low as possible, but your tap level will affect that.

There are some ways to reduce nitrates (other than water changes) though none are really as easy as they sound on paper:

1) grow plants - plants use up nitrate (if there is no ammonia available to use) and thus will reduce nitrate levels

2) grow algae - algae uses very similar nutrients to higher plants, and if cultured correctly will be more efficient than any other filter (though it is not easy to get it so)

3) introduce an anoxic (nearly devoid of oxygen) zone to the filtration - these are a nightmare to get right to reduce nitrates but if you are lucky enough (or have the flow pump connected to an oxygen sensor and controlled by a computer) then they can work well

 

[dgwebster]

an also purchase nitrate treatment, though their effectiveness and use is debateble.

 

[Leslie]

Also, how much do you feed? An excess of food can cause big nitrate changes as well.

 

[ey2006]

You need to find out what your tapwater levels are - let a sample stand for 24 hours and then test.

If you have excess nitrate in your tank, but a low tap nitrate, then the only thing that will help is to reduce stocking levels or perform more/larger water changes more often.

Where I am, it comes out of the tap at pretty much 40ppm. I'd say anything above 50ppm long term is not good for the fish. Adding plants will help to use nitrate and reduce levels.

I tested the tapwater (after letting it stand for 24 hours) and the Nitrate reading was 10ppm. Is this a good reading? Because I only change 15-20% of the water each time I perform a water change, it probably isnt enough to see any real effect on Nitrates dropping, should I do larger water changes in the future, say 30-40%? I'm not sure if the fish will appreciate it though.

Would excess stocking levels also be a cause for high nitrate levels?

 

[ey2006]

The general guide is that so long as your fish are not very sensative (read rays et al) then under 100 ppm is ok. Ideally you want to aim as low as possible, but your tap level will affect that.

There are some ways to reduce nitrates (other than water changes) though none are really as easy as they sound on paper:

1) grow plants - plants use up nitrate (if there is no ammonia available to use) and thus will reduce nitrate levels

2) grow algae - algae uses very similar nutrients to higher plants, and if cultured correctly will be more efficient than any other filter (though it is not easy to get it so)

3) introduce an anoxic (nearly devoid of oxygen) zone to the filtration - these are a nightmare to get right to reduce nitrates but if you are lucky enough (or have the flow pump connected to an oxygen sensor and controlled by a computer) then they can work well

Thanks for the replies.

Andywg, I already have some plants in the tank - java moss, java fern, amazon swords, thin vals and some crypts. Is this sufficient or should I increase the number of plants?

With regards to Algae, I thought that any algae wasnt good for the tank and that algae was hard to control, hence why people like to get algae eaters or bristlenoses.

I'll keep up with more frequent water changes and see how it goes.

 

[Bloo]

Would excess stocking levels also be a cause for high nitrate levels?

I regularly do a 40 - 50% water change weekly on all my tanks. Yes, higher stocking = more waste = higher nitrate levels.