Cycling Questions

Hi All

I'm cycling my first tank with Kleen Off Ammonia.  All is going well, I think. I am on Day 18. I just have a couple of questions to make sure I'm doing it right. 

I have been testing my water every 24 hours.  Recently every time I test both the Ammonia and Nitrite have been 0ppm and Nitrate has been 80-160ppm, maybe more.  I have been advised to do a large water change when the Nitrate is very high because it could stall a cycle. I did my first almost 50% water change yesterday, is this the right thing to do?

I have decided to start testing 12 hourly now, as 24 hourly shows 0ppm Ammonia and Nitrite every time.  This morning was my first 12 hour one:
Ammonia - 0.50ppm
Nitrite - 5ppm
Nitrate - 80-160ppm (despite large water change last night)

I know I have got to add more ammonia every time it falls below 1ppm.  I was always adding it after my 24 hourly tests, but do I still have to add it 12 hourly if below 1ppm?  Just checking I'm not adding it too often.

I hope this makes sense.  Let me know if it doesn't.

It sounds as though you are doing the old version of fishless cycling. There is a more up-to-date fishless cycling  method which does not have the problems of the old one.

In the old method, ammonia was topped up every time it fell below 1ppm. It is now known that this causes nitrite to go above 15ppm, which stalls the cycle as the nitrite eating bacteria do not multiply above this level, and it makes too much nitrate which also stalls the cycle.
This method usually adds ammonia to 5 ppm which is far more than a fully stocked tank will ever make in 24 hours.

The newer method is designed so that too much ammonia can never be added, so nitrite never gets high enough to stall the cycle and neither does nitrate. It also uses the fact than the filter bacteria do not starve if they are not fed when ammonia drops to zero as used to be thought. It also does not test after 12 hours, the cycle is finished when the tank can clear 3 ppm ammonia in 24 hours.
This method uses 3 ppm ammonia as even this is more ammonia that a fully stocked tank makes in 24 hours

fcmf has given you the link to this newer method. I would drain as much water as you can out of the tank and when you have refilled it, add ammonia to 3ppm and follow the method in her link. I would make one deviation from that method though - since you have already grown some bacteria, instead of testing every third day at the start I would test every second day. Because you have already got some bacteria, the cycle should progress quickly.

Good luck for a rapid and sucessful tank cycle. 

I just need to double check what I do next in my cycling?
I'm on Day 3 of cycling (using the new version as advised), just tested for Ammonia and Nitrite - both are 0ppm.
These are the results I was getting every 24 hours after adding Ammonia when I was cycling the older way.
Looking at what I am supposed to be aiming for at this stage of cycling, I think I am already way ahead.

So...shall I just continue following the steps as normal and do nothing now and test again in three days, or shall I move straight to any further steps in the cycle?

Thank you - I will dose it now and keep you updated

Yes you are cycled. If the tank can clear 3 ppm ammonia to zero ammonia and nitrite in 24 hours, the tank is cycled.


If you did the big water change a few days ago, you shouldn't need to do another unless you have to wait till next weekend to go fish shopping.
If you do need to wait, add 1 ppm ammonia every other day, then do a big water change the evening before or even the morning of shopping day.



As regards fish amounts, if you use the Community Creator on here, don't go above 75% for the first 3 to 6 months, even with fishless cycling. This gives you a bit of wiggle room should things go a bit awry.

Yes you should, you need to get your nitrate to the same as your tap water. Leave the water change till just before you get fish because if it will be a few days yet you'll need to feed the bacteria (1 ppm every other day) and this will make more nitrate.

Great news on completing your fishless cycle.