Tropical Fish Forum

Tropical Fish Keeping Help and Advice => Fishtank Filtration and Cycling => Topic started by: dbaggie on December 16, 2013, 04:21:15 PM

Title: Cycling - No Nitrates?
Post by: dbaggie on December 16, 2013, 04:21:15 PM
Hi all, I've been using Think Fish for a while now but this is my first forum post!

I've recently upgraded from a small tank to a 180 litre with my original tank having been running for about 18 months and containing just Danio's. My new tank has been up and running with fish for just over 6 weeks but my tests have never shown any Nitrites, which has me confused. Can anyone shed any light on this??

My initial readings were: ph 7, Ammonia 0.5ppm, Nitrites 0ppm, Nitrates 80ppm. The ammonia dropped fairly quickly to 0.25 and then to 0 in just over a week (daily tests). Nitrates dropped a bit more steady but are now around 20ppm. My ph is now around 6.6 - 6.8. N.B. As well as the Nitrites no show, the lack of any significant ammonia spike also seems unusual? For info, I'm using the API Master Test Kit.

Bit of background: I added only used (although thoroughly washed) gravel to my new tank and ran it for over a week before adding any fish (the first fish added were the Danio's from my existing tank and no more fish were added for another couple of weeks). Also, again before adding any fish, I added water from my existing tank daily, put a piece of my existing (and un-cleaned) filter media into the new filter and added some fake plants which were again from the existing tank.

When my Danio's were transferred to my new tank I had no use for the original tank so added the rest of the water and also transferred the filter - this has been running in my new tank up until last week.

Would the above steps have been sufficient to generate the ammonia and nitrite readings I've had? For info - I spotted another post which said that nitrite readings can sometimes shows a nil because they're 'off the chart' so I have re-tested my water for nitrites with a 1 in 10 dilution; again the reading was nil.

Any help/advice would be appreciated!

Title: Re: Cycling - No Nitrates?
Post by: Sue on December 16, 2013, 07:18:50 PM
I'll deal with nitrate first. This is the most unreliable test in our kits. It is very difficult to make a really accurate one for use in the home. Nitrate readings should be taken as ball park figures. And in addition to their lack of accuracy, with liquid reagent kits one bottle has to be shaken really well and failure to do this creates an even bigger inaccuracy.
In other words, don't worry about nitrate readings too much.

Ammonia and nitrite kits are reasonably accurate; certainly good enough for our needs.
You say you moved mature media and the filter from the small tank into the new one - that is why you haven't seen any nitrite. The trace of ammonia you saw was because you would have lost some biofilm that was on the glass in the old tank and also on the gravel after you washed it. The filter bacteria live in the biofilm; the majority of bacteria are in the filter media because of the large surface area in sponges etc, because they like to live where the water flow is good, and because they like to live in the dark but there are some in the biofilm that coats every surface in the tank. It just took a few days for the ammonia eaters to multiply enough to replace the ones that were lost. And because they only produced a small amount of extra nitrite as they multiplied, the nitrite eaters were able to multiply fast enough to cope with it.
It's when you cycle with just brand new media, whether it's fishless or with fish, that you see big ammonia and nitrite spikes. Using old media as you did, you can get away with just mini spikes, if even those.


You say the old filter was running in the new tank till last week - have you removed all the old media as well or have you put it in the new filter? If it has all been taken out, keep an eye on your stats as there won't be many bacteria in the new media yet.
Title: Re: Cycling - No Nitrates?
Post by: dbaggie on December 22, 2013, 04:24:21 PM
Thanks Sue