Ammonia -> Nitrate

[whall]

Hello folks,

I have a 60L tank that is now about 3 weeks old and for the last 2 weeks has had 4 danios in it (I found out the truth about fishless cycling a little too late im afraid).

I have been testing the water in the tank on a daily basis and doing 25% water changes every other day, despite a bit of a scare which I mentioned in a previous post all fish seem to be swimming around fairly happily, but there is something strange going on.

I have the API test kit and I am now starting to see the appearance of Nitrate in the tank. I keep Ammonia as low as I can but one test showed it over 1.0 which scared me so I did a 50% water change and got it down to 0.5 and I have been holding it there or below since. Now I am seeing my ammonia levels get closer and closer to 0.

However, every Nitrite test I have ever done has read 0, and todays test of Nitrate reads 5.0. It has been 0 every other test so it does seem to be a result of something happening in the tank. I am confused though, how could I have missed the Nitrite step?

Is there such thing as a bacteria type that consume Ammonia and emits Nitrate? Is it likely that my Nitrite test is faulty somehow? (either user or manufacturing error)

I am not sure if this is relevant but there does appear to be something growing on one of the (fake) log decorations in the tank. It looks like a kind of translucent, very very fine fur, or a very dense, but delicate cobweb. Perhaps some kind of mold?

 

[waterdrop]

Well, sounds like you're doing a lot of things right. I would be suspicious that perhaps the water changes should be every day if possible, just to be safer about it. It may be that 4 danios, lightly fed, put out such a small amount of ammonia that 25% change every other day is indeed taking care of it but it would be safer to be very suspicious and to consider that you should be ready to do more at any moment.

Its indeed possible that the nitrite part of the kit is bad, but its probably a pretty small chance. Its also likely that you just have small numbers of both types of bacteria at this point and so very small amounts of ammonia are being changed into nitrite and then small amounts of nitrite are being changed into nitrate and you're just not able to see the transitional nitrite - this is not so uncommon in your situation. Just keep in mind that it is extremely unlikely that the filter would get cycled before 4 weeks and you just need to keep testing and keeping both those numbers as close down to zero as possible until that 4 weeks has gone by and then would be the time to not do a water change and see what readings you get. When it can go two days in a row without a water change and showing complete zero for both poisons, you know that its cycled. If money is not an issue, you could buy just the API nitrite kit by itself and see whether the new bottle you buy shows something different (or get a Salifert or Nutrafin individual nitrite kit just for the heck of it..)

~~waterdrop~~

 

[Miss Wiggle]

yup as WD said it may not seem to make much sense but it's certainly not unusual to see this. it's most likely that you have a small amount of both species of bacteria now present, up until this point they've not been making any tangible difference to the levels (it does take a little while to start) so the only thing that's kept ammonia and nitrite down is the daily water changes. now because you're starting to get more bacteria growth you'll have had some nitrite production, the NBcas though have been able to handle it and it's gone straight through to nitrate. I would now expect to start to see some nitrite readings over the next few days.

three other factors to weigh into the equation though, firstly the nitrate test kit is not brilliantly accurate, it's the best available to us but results should be taken as indicative not exact, so it coule be that the level of nitrate in your tap water is around 2/3ppm and on your kit it's previously shown as 0 but now shows up closer to 5ppm.

secondly the tap water nitrate level may fluctuate a bit, so it could just be that you've added some nitrate in with your water changes if todays tap water happened to have a smidge more nitrate in than normal.

and lastly, it is possible that the nitrite reading is faulty. to confirm/deny this take a sample of water, test it yopurself then take it to the lfs and ask them to test it, then compare the two and you'll see any discrepancies.

 

[OldMan47]

Another issue with the nitrate testing that I don't see mentioned is the need to mix the reagents very well. Forget the 30 seconds and give a really good mix for at least a minute for the reagents. The 30 seconds might work sometimes but anything less than a thorough mix can give you false readings. I know my arm starts to hurt a bit if I actually mix my reagents long enough to trust the results but I really want results that I can trust.