Ammonia - Fishless Cycle

[rebeledd]

Hi all,

The good news is my tank is already on the way to being ready for fish. Yesterday I added ammonia to take the levels up to 4ppm and it was back at 0ppm this morning.

My first question is how long can the bacteria live without food? Obviously I will be testing every day and adding more ammonia if necessary but my concern is that it may drop overnight and not have any food. How often do people normally check when it's dropping this fast?

My second question is to do with nitrites. At the moment the nitrites are off the API test kit chart even though the nitrate is 20ppm. I have been reading online that people recommend a water change if they are too high? Should I simply wait and keep adding ammonia or should I do a water change, if so how big a change?

Thanks in advance.

 

[Shaddex]

Its good news that your filter is processing 4ppm ammonia in a day, but you are a way off adding fish until your Nitrite level also drops to 0ppm.
 
I would suggest that as your Nitrate is only 20ppm (That's my tap water level) you do not have any Nitrite Bacs in your filter yet, and unfortunately these take longer to populate your filter than the Ammonia Bacs.
 
Don't worry about your Nitrate level until your Nitrite levels drop.  Your Nitrate level will go off the chart once the Nitrite Bacs start working.
 
Once your Ammonia and Nitrite levels are 0ppm after 12 hours (After you add 4ppm ammonia) you can then do a  90% water change to get rid of the Nitrate.
 

Answer to 1.  You wont have any issues loosing Bacs over night.
Answer to 2.  Water change is not needed until your NitrAtes go off the scale, indicating your Nitrite Bacs are hard at work.
 
Also.   Check you PH levels.  Mine dropped to 6.2 which can stall the cycle.

 

[rebeledd]

Nice answer, thanks for your help.
The PH is at 7.4 at the moment. What is the ideal range and how do I adjust this if it changes?

Even though the nitrite is off the chart will it drop to 0 when there is enough nitrate? How long do you reckon this takes in a 20l tank?

Thanks again.

 

[Shaddex]

7.4ph is fine.  Keep water temp up at about 26+ as this will speed along the cycle.
 
Ammonia -> Nitrite -> Nitrate.  Water changes to remove Nitrate ( Or plants etc )
 
Once your Nitrite Bacs have multiplied to sufficient numbers, they will convert all the Nitrite to Nitrate.
Then once a week (ish) 25% water change to bring down the Nitrate levels.
 
Based on my experience, it takes approx 30-40 days to fully cycle a tank from scratch.
 
Read the "Fishless Cycle" link in my Signature.

 

[rebeledd]

Thanks for that. I was in my local fish shop today and was talking to them about the cycle.

They told me that I should now stop feeding the tank ammonia until I see nitrate, is this true? I have also heard that you should reduce the dose of pure ammonia at this stage.

What is normal practice? Thanks again

 

[Shaddex]

Wait until your ammonia drops to 0ppm, then re-dose to 4ppm.
 
If you do not feed your A.Bacs ammonia they will die off.  Keep up the Ammonia dosing until you see 0ppm on both Ammonia and Nitrite after 12 hours.  Then you are cycled.
 
Nothing wrong with doing a partial water change to reduce the Nitrite levels, but not worth it in my opinion.

 

[cpwebsite]

I agree with Fishaholic, there is no need to change what you are doing, just keep at it and wait till your nitrites go to 0 dosing the same and then you are fully cycled.