Fishless Cycle

The friendliest place on the web for anyone with an interest in aquariums or fish keeping!
If you have answers, please help by responding to the unanswered posts.

shizzy2342

Aquarium Advice Newbie
Joined
Mar 15, 2025
Messages
6
Location
CT
Hello, I am redoing a 70 gallon tank and decided to do a fishless cycle as the first time I did this tank was a mess with a fish-in cycle. This is my first fishless cycle, I did the dr. tim's ammonia dose method. I was about 23 days in when I finally started seeing nitrites and the ammonia I was putting in was being processed in a day (showing 0ppm the next day). I continued dosing the ammonia every day adding about 1ppm and seeing it hit 0 the next day. The nitrites spiked to 5 during this time and for about 2-3 weeks started to drop to about 0.5ppm. I decided to stop dosing the ammonia about 3 days ago and now my nitrites are back up between the 2 and 5ppm on the API test kit. Is this normal? I am on day 53 and its getting incredibly frustrating lol Ive been dosing with bacteria since the start too, adding small doses every couple days or so.
 
Cycling a tank, whether fish in or fishless, will all depend on your water's parameters for speed. Optimal conditions for nitrifying microbes is pH 7.4-8.0, Temperature: 77-86, Alkalinity: above 80.5 ppm KH and phosphate levels above 0. So if you do not have these levels your cycling time will be longer or if your pH is below 6.0, it may be non existent. FYI, 53 days to cycle a tank is not unusual at all. It generally takes 2-3 months on average under optimal conditions. This is why fish in cycles at least have something to look at during the months it takes. The only advantage to fishless cycles is not potentially killing fish, not speed of the process. I'll also add that adding bottled bacteria can be a 50/50 deal. Maybe it works and maybe it doesn't. You have no way of knowing that the product was actually alive when you got it and if the water parameters aren't optimal, they won't work at optimal speed even if they are alive.

What doesn't make sense is that your nitrites rose a second time. The nitrites rise from the conversion of ammonia so with no new amounts of ammonia, there shouldn't be higher nitrites. Either the test result was wrong or something is missing in the story. 🤔

I would definitely continue adding the ammonia because if you don't, you will kill off the microbe that converts it to nitrites by starvation. Keep testing the nitrites to confirm your readings or have another test kit or outside source confirm your readings. (y)
 
Thank you!!! I appreciate it, Yeah my pH has been around 7.4-7.6 the entire time, however it did drop below 7 once and i added a pH boost. I raised the temp early on to about 83 and that definitely sped up the ammonia to nitrite process. That is what is confusing to me, I don't get why the nitrites rose again. The only thing i added in the last three days was the bacteria. I was hoping by skipping a day of the ammonia it would take that last push to convert the last 0.5ppm of the nitrites. I'll see what the results are today, my nitrates have been consistently at about 20ppm the last couple weeks too, so I'm hoping this was like maybe some random spike before the final push... fingers crossed lmao
 
and it actually could be the test kit too, maybe I should look for another source to confirm like you said
 
Thank you!!! I appreciate it, Yeah my pH has been around 7.4-7.6 the entire time, however it did drop below 7 once and i added a pH boost. I raised the temp early on to about 83 and that definitely sped up the ammonia to nitrite process. That is what is confusing to me, I don't get why the nitrites rose again. The only thing i added in the last three days was the bacteria. I was hoping by skipping a day of the ammonia it would take that last push to convert the last 0.5ppm of the nitrites. I'll see what the results are today, my nitrates have been consistently at about 20ppm the last couple weeks too, so I'm hoping this was like maybe some random spike before the final push... fingers crossed lmao
Check and make sure your source water does not contain nitrates. THAT and with the API kits, you can get a false nitrate reading when there are nitrites present so a consistent nitrate level says to me that it's a false reading if they are not from your source water. When fully cycled, the nitrates should always be rising, not steady. (y)
 
Thank you so much!!! That makes sense, I'll check the nitrates on the source water! Yeah the nitrates definitely haven't been always rising so I wouldn't be surprised if it was a false reading, I'll go back to adding the ammonia today too. It'll be so rewarding when it finally fully cycles lol
 
Check and make sure your source water does not contain nitrates. THAT and with the API kits, you can get a false nitrate reading when there are nitrites present so a consistent nitrate level says to me that it's a false reading if they are not from your source water. When fully cycled, the nitrates should always be rising, not steady. (y)
okay just took todays results, pH is at 7.6, 0ppm ammonia, 0ppm nitrites now, and now 40ppm nitrates, its cycled right?? I don't understand what yesterday's nitrite spike was about or maybe it was a false reading? I think now I do the 2ppm dose of ammonia and if its 0ppm ammonia and nitrites 24 hours later, I should do a small water change and I can add fish right?
 
okay just took todays results, pH is at 7.6, 0ppm ammonia, 0ppm nitrites now, and now 40ppm nitrates, its cycled right?? I don't understand what yesterday's nitrite spike was about or maybe it was a false reading? I think now I do the 2ppm dose of ammonia and if its 0ppm ammonia and nitrites 24 hours later, I should do a small water change and I can add fish right?
Correct. You want to make sure that your system can convert that 2 ppm of ammonia into nitrates in 24 hours and if it can, you are fully cycled. (y) Then you do the happy dance :dance::dance: maybe a few of these :multi: and then do a large water change to reduce the nitrates to as low as possible and either put fish in within 3 or 4 days or keep adding ammonia until you are ready with fish. (y)
 
Correct. You want to make sure that your system can convert that 2 ppm of ammonia into nitrates in 24 hours and if it can, you are fully cycled. (y) Then you do the happy dance :dance::dance: maybe a few of these :multi: and then do a large water change to reduce the nitrates to as low as possible and either put fish in within 3 or 4 days or keep adding ammonia until you are ready with fish. (y)
Nice!!! Thank you so much lol I was worried yesterday thinking the nitrite process got messed up, definitely will be doing the happy dance if everything is good tomorrow hahaha
 
Back
Top Bottom