Help with extremely high nitrite levels!

[nbhoover]

I am in serious need of help. My fishless cycle has been driving me bonkers!

I have been doing a fishless cycle for about two months now on a 30-gallon freshwater goldfish tank. The tank is moderately planted with four plants, one of which is anchored to a small piece of bogwood. I use an internal filter (couldn't use a HOB because the edges of my tank were too thick) as well as a sponge filter for aeration and additional biological filtration. For substrate, I have medium-sized gravel, a few larger river rocks, and a mixing of lava-type rocks throughout. All the substrates were purchased from a pet store.

As for my routine, I test the water parameters almost every day. For quite some time, I've had readings of ammonia, nitrite, and nitrate. In the beginning, I dosed ammonia to 4ppm. Now, I dose pure ammonia to 1ppm, then wait for that to go down to .25ppm or almost 0 before re-dosing. The ammonia decreases almost to zero within 24 hours.

Nitrites are another story. They began steadily appearing several weeks into the cycle, but they've yet to go down! For the last month, nitrites have been through the roof (5ppm+). The only time the nitrites go down are when I do 100% water changes. But inevitably, the nitrites come back up and are sky-high by the next day.

I've had readings of nitrate, varying between 10ppm and 160+ ppm.

I've tested my tap water, and it contains no nitrites and no nitrates. I've been keeping an eye on my pH, and it fluctuates between 7.6 and 7.4, but I always do a 50% water change and add Prime when I notice any fluctuation. Prime is added anytime I do water changes, and I haven't messed around with my internal filter in any way since I began the cycling process.

Why won't my nitrites go down?

 

[Mattyfelts]

stop dosing ammonia, dose like 4 ppm, watch it change and if it turns to nitrate in 24 hours your golden.

it seems like your still cycling.

 

[Masha]

It sounds as though you are nearing the end of the cycle. You've got the ammonia > nitrite bacteria, but the nitrite > nitrate bacteria always takes longer to get up to speed. Apparently they take longer to duplicate.

You are doing the right thing in doing water changes to reduce the nitrites, as that can apparently stall the cycle. (For some reason, although the bacteria you are hoping to grow needs nitrites, too high nitrite levels inhibit their growth)

You have already lowered your ammonia dose to 1ppm, right? That's also a good idea, as 4ppm seems to be too high and often causes these too high nitrite levels.

Keep your ammonia levels at 1 or 2 ppm, do water changes when the nitrites get too high, and the cycle should complete soon. You've eliminated possible problems like too-high ph, so that should not be a problem. If you can get filter media squeezings from and established tank, that should help too.

 

[PNWaquarist]

I agree that you're likely experiencing the nitrite spike near the end of the cycle. The nitrite-oxidizing bacteria take longer to reproduce than the ammonia-oxidizing bacteria. It sounds like you're doing everything right.

Some say that > 5 ppm nitrites will, paradoxically, inhibit the growth of nitrite-consuming bacteria. This is somewhat controversial, but there is observable evidence to support it. Do 50% water changes until your nitrites are below 5 ppm and then don't add anything for a day or two. Then dose with 1 ppm ammonia until your nitrites begin to decrease. At this point, dose with 3 ppm ammonia and see if your bacteria can convert all of it to nitrate within 24 hours. When it can, you're cycled. Do an 80%+ water change and get ready to add fish.

EDIT: Another somewhat controversial claim is that ammonia- and nitrite-binders like Prime can slow bacterial growth and stall your cycle. Because of this, I'd not use Prime unless it's necessary (e.g., if you do a water change).

 

[ppo8820]

I am in the EXACT same boat, but its actually a good thing. First we had the ammonia. After I dosed, it sat at 4ppm for like 2 weeks. Then one day it was at .25 and Nitrites started to kick in. Now they are at about 5, and ammonia slowly leaves every time I dose within 24-36 hours. Im just waiting til the morning I test and they are both at ZERO and I finally complete my first fishless cycle. We are on the right track!