Nitrites

[GingerGandalfff]

I'm cycling my new tank, it's about 12 days in. My ammonia was at 5ppm so I did a water change to try and bring it down because it has been up that high for days. My nitrites are the highest on my scale reading 5ppm with the API freshwater test kit. I've done a water change today and now my ammonia has dipped down to 2ppm but the nitrites are still reading the same. Is this okay and if not have I done something wrong? I'm a newbie to all this and this forum has been so helpful. Thanks in advance.

[Gingerlove05]

It depends what the nitrite reading was before the water change, if it was 5ppm before and you did a 50% water change it would drop to 2.5ppm. If it was 12ppm (unreadable by the test as it maxes at 5ppm), it would read 5ppm on the test but a 50% water change would bring it down to 6ppm, so it would still show 5ppm on the nitrite test. Hope that makes sense.
Just keep an eye on the ammonia dropping to 0ppm, nitrites can stay off the chart for 10days+ while cycling but they will drop suddenly (more or less overnight) once the munchers catch up

[mikeyw64]

Are you cycling it fish in or fishless ?

If you're doing a fishless cycle then no need to do water changes yet, just let nature take its course

[plankton]

If I read correctly you've done a water change to bring the ammonia down and the nitrites still read high.
That's fine.
Top the ammonia back up to 2ppm when it goes down to zero.

[Jon_D]

You need Ammonia to get the bacteria to consume it and produce Nitrite.
You need Nitrite to get another form of bacteria to consume that and produce Nitrate.
The Nitrate so produced fertilizes your plants.
Your fish will excrete Ammonia.
And so the cycle continues.

[GingerGandalfff]

It's a fishless cycle! So just keep an eye on ammonia, wait till that drops to 0 and boost back up to 2. Is there a reliable way to measure the ammonia? I have a 2ml syringe and all these online calculators give me different readings! The 50% water change didn't bring it down below 5 so I can imagine it was quite high.

[Gingerlove05]

Somewhere in the back of my mind the number 2.14ppm (or 2.54ppm...) nitrite is produced for every 1ppm ammonia. So if it was 5ppm ammonia it would produce 10.7ppm nitrite (12.7ppm if its 2.54). Euther way half would still be over 5ppm...just

[mikeyw64]

Perfect.

Yup just wait for the ammonia to drop to 0 then top it back up and keep repeating until such point as you get 3 consecutive days of zeroes on the ammonia and nitrites.

That's the point at which you may need to do a water change if your nitrates are still high.

As for how much ammonia to add I used this forums calculator

If you have a planted tank you should be aiming to keep it at 2ppm rather than 4ppm.

Don't forget to adjust for the strength of ammonia you're using (I used 40% rather than 10% so added less each time) and also rather than using the full empty volume of your tank I would use a 75%-80 figure to allow for decor and not completely filled etc.

After adding more ammonia I also checked about an hour later to see where it was at and adjusted the amount added accordingly.

Another useful tip is to run your tank between 30 & 35c when fishless cycling as the munchers will grow faster

[mikeyw64]

For reference this is my log of cycling Sunnyside earlier this year.

Note I started with Dr Tims for the ammonia then switched to the 40% mix (works out cheaper lol)