Mucho Nitrate, no ammonia or nitrite - what's happenning?

[ormali]

Just tested the 4ft tank after my betta lady looked a bit off colour - we have a major nitrate problem - off the scale problem. It is redder than the test cards cater for

Everything else in the water is fine - no ammonia at all, no nitrates, PH is 6.5. Tank is very heavily planted and has lots of floating plants. Has quite a high fish stock level but has always done so and coped well.

Any ideas as to what caused this? Water was fine when I tested not this last weekend but the one before. Tank has been up and running for over 6 months now.

Help? Did a 60% water change last night and the nitrate is still through the roof.

Fish seem to be coping and my plants are growing very nicely but I dont think we want this to continue.

Thanks in advance.

[Brianemone]

i didnt think you wanted ammonia anyway??

water changes are the best and easiest way to bring them down, just do 10% every other day untill you reach your target. revise your filtration and stocking levels to

[Sharkey]

And I would test your replacement water. Seems strange to be that high after such a large water change? :-?

[Faran]

This may sound silly, but test some bottled water as well. Your test kit may have gone off? Otherwise it's water changes to correct but with a steady cycled system there shouldn't have been such a spike. When's the last time you did maintenance on your filter?

[mustcooktea]

Are all your fish accounted for? Perhaps one is deceased and rotting among all that plant cover.

MCT

[DiverJohn]

This may sound silly, but test some bottled water as well. Your test kit may have gone off?

That was my thought, or perhaps a bit of contamination in your testtubes? GIve them a thourough rince in the sink, then fill, shake and discard 2 or 3 tubes full of the tank water you are going to test.

Also test the water your putting in (as per sharkey's post), something might have contaminated it.

HTH

JJ