No 2 No3 Levels High

why has my no2 levels spiked hugely
no2 2.0 ppm purple maybe 5.0 ppm
no3 5.0 ppm orange
ammonia 0.25 ppm very light green
ph 6.8
did a 25% water change yesterday but forget to test water first
levels have never been that high
my tank is a 4ft 180 litres lots of plants and bog wood
eheim 2010 internal filter (maybe to small)
air-stone off a air pump
4 cherry barbs
5 harlequins
5 neons
2 bolivians
2 bristle nose (small) 2 inch
this tank has been running 3 months since up grading from a 2 ft
all fish seem healthy and swimming around
feed twice a day small pinch

thanks for quick reply
tested water twice just in case . used waterlife tap safe
all fish are healthy and swimming around as normal , my cherry barbs are even mating
 

do you think my filter is to small ? its rated upto 160 ltrs
so most probably just coping with size of tank
don't mind going and buying another filter 

do you think my filter is to small ? its rated upto 160 ltrs

Yes, you could do with a larger one for that sized tank, but if it coped with the same number of fish in a smaller tank then it should cope with those fish in a larger tank as it's the amount of fish waste that the filter bugglies respond and increase to. And anyway; it wouldn't have caused such a sudden increase after three months.

If you swap some media between the two filters so they each have half old media and half new, the bacteria will migrate into the new media in each filter quicker than all the old media in the one filter. Physical contact between old and new is the best way eg since they are Eheims, mix new and old substrat pro in the same basket.

But you'll still need to do water changes to get that nitrite down until your bacteria do multiply enough.

Do a big water change then test after hafl an hour (to allow the new water to mix in). If nitrite is still above 0.25, do another big water change, test after half an hour and so on until the reading is below 0.25. Then test every day and do as many water changes as big as necessary to stop the nitrite getting higher than that reading.

However, with a reading you report the fish should be gasping at the surface. Their gills should be brown instead of red.
What are you using to test with, and is it still in date?

50 % water change done
ammonia 0
nitrite no2 0
nitrate no3 hard to say between 0 and 5.0 . slightly darker than yellow
will test again tomorrow
fingers crossed

That's good news.