Why is my new tank not cycling?


I set up my tank about 4 weeks ago, added water, dechlorinator, turned the heat up to about 80 degrees F, ran my biofilter, and added pure ammonia. 4 weeks later, my ammonia levels are still high, and nitrites and nitrates are non-existant. It's as if nothing is happening. I am sure this is a result of no bacteria being present in my tank, but why? I follow the directions people give on fishless cycling to a tee, Is there something I can do to help it along?

And I do not have access to someone else with a tank so it's not practical to get something from an established tank to add to mine, thanks.


Welcome to FL!

Cycling takes around 6+ weeks, so you might still be on track, although I would think you should see some changes by now. If you still want to do fishless cycling, wait the full 6+ weeks for results.

What are the water parameters of your source water? If the pH is low, especially around 6.0 or less, the tank will not cycle.
  • Thread Starter


The pH is around 7.5/8 and from what I've read, that is ok. It just seems like I dumped water in, added ammonia, and it's all just sitting there. :-/


Hello there and Welcome!

First, lets step back and tell us exactly how you have been doing the fishless method.

When you first started, how much ammonia do you drop in DAILY and how do you test your water parameters?

Are you using the pure ammonia ( janitorial grade ) and not any with additives ( soaps, etc )

Are you using a liquid test kit DAILY to do this?

Are you changing out any water?

What size is your tank and what kind of equipment are you running?

Also, I know this may sound stupid but just checking to make sure you are NOT using any type of water conditioners, etc

Again, an average time for a fishless cycle using the pure ammonia method is usually 4-6 weeks - some times a bit longer.

  • Thread Starter


When I first began the cycle, I don't remember exactly how much ammonia I put in, it was enough to raise it to 4ppm. I since then have been testing frequently (not daily) to check the ammonia levels and like I said, they've been stagnant. Nothing is happening at all.

The tank is 30 G running a Penguin powerfilter and heater set at 80 degrees.

The only conditioner I used was before the ammonia was added - it was a standard dechlorinator.

I am using janitorial grade ammonia, nothing with detergents or surfactants.

I am using an API freshwater kit to test for all my levels. Again, the ammonia consistently tests positive, currently on the lower side (about 2ppm) only because I did about a 40% water change since nothing was happening. The nitrite and nitrate levels are 0 still after all this time and ammonia has yet to decrease on it's own.


What exactly is a standard dechlorinator? Basically, a dechlorinator will kill off any bacteria. If you've added that more than once, there's your problem.
  • Moderator


I wouldn't think a water conditioner (dechlorinator) would kill off any bacteria.

You may have slowed your progress down by doing that water change. You want to keep your ammonia level at 4ppm until nitrites show up, then keep it at 2ppm until nitrites zero out and you can process the 2ppm of ammonia within 24 hours (at which point you'll be cycled).

It can take 3-4 weeks of keeping your ammonia level at 4ppm before the bacteria that converts ammonia into nitrites develops, so you need to be patient (I know, it's hard for me to be patient too!)

You could always drain the tank, refill and go the SafeStart route. That would allow you to put fish in right away.


You didn't mention it and no one else did either so I thought would tell you that you can speed up your cycle by adding some Tetra Safe Start. TSS can also be used to cycle a tank with fish in but don't do this now because you already have ammonia in your tank. I have cycled 3 different tanks using TSS and ammonia and NO FISH and they all cycled within about 2 weeks.
Like Junne says you need Janitorial strength ammonia - make sure it doesn't have any thing it it but ammonia. My bottle says 10% ammonia hydroxide and came from Ace Hardware.
Pour the entire bottle of TSS in the tank. I usually pour mine in the filter media and let the filter flow push it out into the tank. I don't know if that helps but it makes me think it does so I do it.
I put one drop of ammonia in per 10 gallons and then tested until I had an ammonia reading on my API test kit. Anything above zero was good enough for me. Do this every day... but test before adding and if the ammonia is still high... don't add more... or at least I didn't because my ammonia would get crazy high if I kept adding.
Once my ammonia started dropping I would test for nitrites and nitrates and add a little more ammonia. At this point I would test ammonia, nitrites and nitrates daily until the nitrites were zero for several days. When this happens the nitrates will rise above 5ppm, which is what you want. By now the ammonia should be dropping pretty fast too. The tank is cycled and you are just feeding the bacteria. At this point I would drop in a few flakes of fish food and stop adding ammonia. The food is to put something in the tank for the bacteria to eat since the tank until now is pretty pristine and we are cutting off the food supply. We want a zero ammonia reading before we add fish.
Also, once the nitrates get to around 20ppm you need to do a partial water change...

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