Water Changes in a Fish-Less Cycle (Using Ammonia)

cmid21

Member
Hello,

I had a general inquiry, while trying to keep busy in relative isolation, regarding water changes starting a fish-less cycle and dosing ammonia. I was surprised to find that the step-by-step information is rather scarce (relatively speaking) regarding cycling a tank using ammonia. I have only ever used organic potting soil for substrate and heavy planting, so that is fairly easy. Basically just let it sit for 6 weeks and the tank is cycled.

Is the basic process of cycling a tank via ammonia somewhat similar?:

Dose up to 2ppm ammonia. Wait for Nitrites and Nitrates to appear. Keep dosing up to 2ppm ammonia until this disappears in 24 hours and the ammonia and nitrite readings go to zero. Finally do a water change after the cycle is finished to remove any nitrates in the water that the plants did not absorb. Cycle complete, good to go? Or are consistent water changes (maybe twice a week or so) needed? Obviously if you are doing a fish-in cycle, you need to do frequent water changes to make the water safe for the fish, but what about for fish-less cycles?

Just through thought experiment, I would think water changes would be counterproductive as you are removing the ammonia and nitrites from the water and just having to re-dose. Is this the case in actual practice? Am I overlooking any beneficial results from conducting a water change during a fish-less cycle? I know sometimes a water change can be akin to turning an electronic device off then on, or blowing into a dvd/cd/game cartridge (showing a little of my age here) to get each to work; it just seems to cause these things to work and no one can adequately explain why. Are water changes similar?
 

Boostr

Member
Nope, just dose ammonia until your cycled and then do the water change before adding the fish.
 

david1978

Member
Some people with a low kh notice there is a point when cycling depletes it and their cycle slows or stalls. A small around 25% water change fixs that.
 

sutty

Member
Purely anecdotal on my part and was no doubt caused by a not so perfect dosing schedule, my tank recently cycled and was clearing ammonia within a 24 hour period but my nitrites were literally off the scale (API/JBL test kits) while producing a decent amount of nitrates - at this point I decided to do water changes, it took 3x50% changes just to bring my nitrites a point where they were readable on the chart. 4 days later they had dropped to zero and my tank was cycled. So I guess it depends, most of the bacteria are on the surfaces/filter media so I don't see how water changes will have a huge impact?
 

Boostr

Member
You have to add the bacteria first though like Tetra Safe Start Plus which I highly recommend. Good stuff.
 

mattgirl

Member
Boostr said:
You have to add the bacteria first though like Tetra Safe Start Plus which I highly recommend. Good stuff.
This isn't necessarily true. I've personally never used any bottled bacteria and have cycled many tanks. Bacteria lives everywhere and will start growing as long as it has an ammonia source. Seems like magic but really isn't TSS+ may speed things up a bit though.

during fishless cycling water changes are only necessary if things such as too much nitrite and/or nitrate accumulate or the PH drops and the ammonia stops going down.
 

emilydupree17

Member
david1978 said:
Some people with a low kh notice there is a point when cycling depletes it and their cycle slows or stalls. A small around 25% water change fixs that.
This is what I’m dealing with currently. My ammonia went down like normal, nitrItes spiked and wouldn’t lower, and the nitrAtes stayed between 0-5ppm. I did a 30ish percent water change and it seems like things are getting back on track. I never knew about KH or GH before this.
 
  • Thread Starter

cmid21

Member
david1978 said:
Some people with a low kh notice there is a point when cycling depletes it and their cycle slows or stalls. A small around 25% water change fixs that.
Very interesting! Thank you for the contribution.

mattgirl said:
This isn't necessarily true. I've personally never used any bottled bacteria and have cycled many tanks. Bacteria lives everywhere and will start growing as long as it has an ammonia source. Seems like magic but really isn't TSS+ may speed things up a bit though.

during fishless cycling water changes are only necessary if things such as too much nitrite and/or nitrate accumulate or the PH drops and the ammonia stops going down.
Yeah, I think people get confused and think they have to buy bottles of X... in order to have a successful aquarium. (That's how companies make their money) I know from my previous tank that bacteria is naturally forming, as I literally filled the tank with water then left it alone for about 6 weeks.

Yeah, I've read testimonials regarding the stalling of nitrites, maybe the bacteria just gets overwhelmed?
Either way, seems like the cycle can stall and then that is the point you should look into water changes in fish-less cycles.

Just in case this might help someone with a stalled cycle:
mattgirl and david1978 , for about how many days of similar nitrite/ammonia readings should you consider the cycle stalled? As in, after 5 days of very high nitrite readings then you are probably stalled. 3 days? 1 week? I know everyone's tank and cycle varies, but what advice would you give when trying to diagnose a stalled cycle?
 

mattgirl

Member
cmid21 said:
Very interesting! Thank you for the contribution.


Yeah, I think people get confused and think they have to buy bottles of X... in order to have a successful aquarium. (That's how companies make their money) I know from my previous tank that bacteria is naturally forming, as I literally filled the tank with water then left it alone for about 6 weeks.

Yeah, I've read testimonials regarding the stalling of nitrites, maybe the bacteria just gets overwhelmed?
Either way, seems like the cycle can stall and then that is the point you should look into water changes in fish-less cycles.

Just in case this might help someone with a stalled cycle:
mattgirl and david1978 , for about how many days of similar nitrite/ammonia readings should you consider the cycle stalled? As in, after 5 days of very high nitrite readings then you are probably stalled. 3 days? 1 week? I know everyone's tank and cycle varies, but what advice would you give when trying to diagnose a stalled cycle?
I consider it stalled when the ammonia slows down or stops going down.
 

david1978

Member
I will be honest. I have never done a fishless cycle myself I have only helped others do it. I can't stand an empty tank. Lol.
 

Boostr

Member
cmid21 said:
Very interesting! Thank you for the contribution.

Yeah, I think people get confused and think they have to buy bottles of X... in order to have a successful aquarium. (That's how companies make their money) I know from my previous tank that bacteria is naturally forming, as I literally filled the tank with water then left it alone for about 6 weeks.
If you don't want to wait 6 weeks for your tank to cycle (like me), TSS+ will cut it in half or less.
 

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