My tank has been cycling for a while now (fishless cycle). Amonia is down to 2 ppm and nitrate is well over 40 ppm, but the test says there is 0 nitrite. Can this be right? I've been dosing Nutrafin's Cycle to speed things up.

Are you sure you dont have 40ppm nitRIte and zero nitRAte? That would make more sense. What are you using for an ammonia source? If your numbers are correct then your nitrogen cycle is not yet strong enough to handle whatever source of ammonia you are providing to it. In other words you have an ammonia spike.

I´m using the API master kit for the test, so I´m sure I got that part right

I´m using amonia I bought at the supermarket as my source (the label is in spanish but it only has one ingredient that would translate into something like amonia hidroxide????)

Ok, so my amonia went down to 1 ppm, my nitrates are now 0.5 ppm and nitrates are 80 ppm. I have brought the amonia level back up to 4 ppm. Read somewhere that if in 24 hours it goes down to 0, and nitrites are 0 as well I can consider the tank cycled. I guess it's going to take a while!

Did you ever see a spike in the nitrite? Adding the Cycle, you may not have seen the spike, as you inoculated the system with a healthy dose of both Nitrosomonas and Nitrobacter. You may have just jump started the entire cycling process and missed seeing the nitrite spike. The 80 ppm on nitrates still seems awfully high, though.

Regardless, since you have the ammonia back to 4 ppm, in 24 hours when you test if you have 0 ammonia and 0 nitrite, I'd recommend a 100% water change (make sure to dechlorinate before adding the new water to the tank, chlorine can play havoc on nitrifying bacteria in high enough concentrations!), check your nitrates on the new water for a baseline as you may have nitrates preexisting in your water source (my water generally runs 5 ppm on nitrates straight out of the fawcet), then take the ammonia back to 4 ppm. Test ammonia, nitrite and nitrate again every 24 hours for three or four days. If ammonia is 0, take it back to 4ppm each day. If every day the ammonia and nitrite are zero, and at the end of the four days you see an increase in nitrates from the baseline reading you established on your fresh water source, then that's a pretty good indication that the tank has finished cycling and all ammonia is being converted completely to nitrate.

I'd still go slow with adding fish and not add too many at once.

WYite

I'm on the third week of my fishless cycle. Yesterday nitrates were around 80 ppm and today they are around 20. Is this possible? I haven't done any water changes. What's going on?

I don't think it's possible unless you did a water change (which you didn't). My guess is the testing procedure. The NitrAte liquid test has a lot of steps that need to be followed precisely in order to get a proper reading. You should also test some tap water. You may already have nitrAte present in the water right out of your tap.

jaguayo wrote:

I'm on the third week of my fishless cycle. Yesterday nitrates were around 80 ppm and today they are around 20. Is this possible? I haven't done any water changes. What's going on?

That isn't possible unless you did a water change. First, double check your readings, as dirtydawg suggested. There is no natural process that significantly breaks down nitrates (a process known as denitrification) in a closed system, such as an aquarium.

Nitrosomonas convert ammonia to nitrite, then Nitrobacter convert nitrite to nitrate. You shouldn't have any nitrate unless you have an active colony of Nitrobacter. Are you still adding ammonia? Have you tested your ammonia level BEFORE you added more ammonia? It appears one of two things is going on here.

First, if you're getting ammonia readings and not getting nitrite readings, then the Nitrosomonas are not converting the ammonia to nitrite as fast as the Nitrobacter are converting nitrite to nitrate. This wouldn't normally be the case, but since you added Cycle you may have created a situation where you have plenty of Nitrobacter and not enough Nitrosomonas. This would explain why you have ammonia and nitrate readings but no nitrite readings.

Second, it's possible the Cycle added nothing to your tank, you haven't seen a nitrite spike because you are still in the beginning stages of the cycling process and your nitrate reading is completely wrong. As I said previously, I don't usually rely on Cycle, but I have used it on occasion when I needed a tank in a hurry. My experience with it has been positive, so I'd be surprised if it added nothing to your tank.

The big variable here is adding the Cycle. If you were getting nitrate readings and no ammonia or nitrite readings, I wouldn't hesitate to say that you fast forwarded your cycling process with it and were ready to add fish. The variance in your nitrate readings is highly unusual. If your nitrate reading is correct, though, as long as you are still getting ammonia readings something is out of whack and ya need to hold off on adding fish. The process I outlined in my previous post would prove that out, or not. It establishes a baseline nitrate for the new water, starts with fresh water with no residual ammonia or nitrite, and allows fresh readings to be taken on all three. Changing out 100% of the water will not kill any established bacteria as long as the water is approximately the same temperature and has been dechorinated prior to adding to the empty tank.

WYite

One last thing just crossed my mind. You do mean your nitrATes are 20 and your nitrItes are 0? The pattern you described for the nitrates of 40 ppm, 80 ppm and now down to 20 ppm actually looks to fit the nitrite spike you should be seeing.

WYite

I tried to ask that earlier in the thread wyite... I really think he has zero nitrates (N03) and 20ppm nitrites (N02). Thus meaning his cycle is almost full. I mentioned this earlier and got a, "I know what I'm doing type response" so I stopped posting in the thread. Im here to help and hopefully we get it figured out but I think my suspicions are correct the N02 and N03 readings are mixed up.

Thanks guys for your replies. It seems that the problem was that I wasnt shaking one of the bottles of the nitrate test thoroughly enough and that's why the nitrates readings were out of whack. My amonia is coming down, my nitrites are at about 5 ppm and my nitrates are now slowly starting to climb. So it seems that the cycle is progressing accordingly and the testing procedure was what I was doing wrong. I added yesterday an ornament from a friend's tank to move things along as well. I'll keep you posted on the progress.

I thought that might be the case. A level of 40ppm of nitrIte is not possible to test with the API kits. I think they max out at 5ppm. Glad you got it worked out.

Cool, good to hear you are getting close!