Fishless Tank Cycle Help

[Fro]

Hello,

I have a Fluval 250l tanks with fluval 307 filter and heater (set to 28). I am attempting a fishless cycle. I set up the tank and added dechlorinator followed by Tetra safestart. I followed Dr Tim’s advice closely using dr Tim’s Ammonium Chloride. As expected, I reached the end of the instructions after 12 days with not much happening. Fully expected it to be overly ambitious and take longer. A couple of days later the ammonia dropped to zero and nitrites appeared. Happy days. It’s now been 5 weeks and I have continued to add 15ml ammonia every few days which drop to zero very quickly (same day). The nitrite however always reads between 0.25 and 0.5 when using my API master test kit. I would have expected the nitrite to go up over time or is that not correct? Any suggestions on what I should do next? Keep patient? Add some more nitrifying bacteria like one and only? Add more or less Ammonia? Add Seachem Prime? Use the aqua sky lights on my tank? Something totally different? Any advice much appreciated. Thanks

 

[Aiken Drum]

Ill post a thorough method for doing a fishless cycle. Following the Dr Tims instructions isnt going to cycle a tank in the timescales they suggest. But really, its about time. You are on the right track, but 5 weeks isnt long enough to cycle a tank.

 

[Aiken Drum]

To cycle a tank you need to grow denitrifying bacteria to consume ammonia and nitrite that your tank produces. The bacteria needs an ammonia source to grow colonies sufficient in size to consume all the ammonia and resultant nitrite and turn it into nitrate which typically you remove through your regular water changes.

A fishless cycle uses an ammonia source to replicate the fish waste that a tank of fish would produce. This ammonia source can be pure ammonia, an aquarium specific ammonium chloride product like Dr Tims Ammonium Chloride, a cocktail shrimp or fish food.

Ill assume we are using an ammonium chloride product.

Set up your tank. Make sure everything is running smoothly. Make sure you have used a water conditioner product with any tap water you have put in your tank. If you have an adjustable heater raise the temperature to 28c/82.5f.

You should have a test kit. Preferably a liquid test kit. It should test for ammonia, nitrite, and nitrate.

Dose the ammonia chloride to approx 4ppm and start testing daily for ammonia. Once your ammonia drops below 1ppm redose it back to 2ppm. This may take a couple of weeks.

Start to test daily for ammonia, nitrite and nitrate. Whenever your ammonia drops below 1ppm redose it back to 2ppm.

You should start to see nitrite and possibly nitrate in your daily tests. Over time your nitrite should start to rise and the amount of ammonia should start to drop further. Your ammonia may start to not be detectable in your daily tests. Keep redosing ammonia daily if you see it below 1ppm. Your nitrite may rise off the testing chart. I prefer to keep nitrite within measurable levels so it shouldn’t hurt to do a water change to keep readings on the chart. Remember to add water conditioner whenever you put tap water in the tank. Nitrate should appear in your water test at some point too.

Over time your nitrite should level off and begin to fall in a similar manner to what your ammonia tests did. When you are able to dose ammonia to 2ppm and 24 hours later see 0 ammonia and nitrite you are cycled. At this point you have enough denitrifying bacteria to consume all the ammonia and nitrite of a moderately stocked tank. You may want to continue dosing ammonia for a few days to make sure it continues to consume all the ammonia and nitrite and be sure your cycle has properly established before proceeding.

Your nitrate will likely be very high. Do a big water change to get nitrate down. Preferably below 10ppm. Adjust your temperature to the needs of your fish. Get your fish, acclimate and add to your tank. I would advise stocking lightly to start with and slowly adding fish until fully stocked.

A fishless cycle typically takes 6 to 8 weeks.

A good way to speed up this process would be to put a small amount of filter media from an established filter into your filter, or get a sponge from an established filter and squeeze it into your tank water. Perhaps you have a friend who keeps fish who could let you have some? This will seed your filter with the bacteria you are trying to grow and speed up the process.

Another option is bottled bacteria like Dr Tims One + Only or Tetra Safestart. These products wont instantly cycle a tank as they claim but in a similar manner to adding established filter media they can seed your filter with the bacteria you are trying to grow to establish your cycle. These products are hit and miss as to whether they work at all, but are an option if established filter media isnt obtainable and may speed up the process from several months to several weeks.

 

[Aiken Drum]

Something weird is happening with your nitrite though. You would expect that to get really high unless you are removing it through water changes or its being cycled out.

Are you doing water changes? What is your nitrate like? Are you sure you are doing the tests correctly?

 

[Fro]

I agree the nitrite is strange. Haven’t done any water changes. I also have some Easytest aquarium test strips and these are showing nitrite at 10ppm but I figured these would be less accurate than the master test kit. The nitrate is reading 5ppm. Does dosing 15ml of Dr Tim’s every 2 or 3 days sound right? On my Seachem Alert sticker it’s only going up to 0.05ppm but did after the first few doses go a lot higher.. The Ammonia is dropping to zero in about half a day after dosing so I’m then leaving it a day or 2 before adding more. Didn’t want to over do the ammonia…

 

[Aiken Drum]

15 ml is 300 drops. 4 drops will raise ammonia to 2ppm in 1 gallon/ 4 litres of water. So your 300 drops will be raising it to a bit over 2ppm. That sounds fine.

Every 1ppm ammonia converts to 2.7ppm nitrite and 3.6ppm nitrate. So you should be able to roughly calculate how much of a total ammonia + nitrite + nitrate will be left in the tank as you havent removed any through water changes. If you have been dosing 2ppm ammonia every couple of days, something should be reading much higher than it is. Personally i would trust that 10ppm + nitrite reading more than the 0.25/0.5ppm reading due to it making more sense. Maybe take a sample to a fish store and ask them to double check.

An ammonia test and seachem alert patch measure different things. An ammonia test is measuring total ammonia nitrogen or TAN (free ammonia + ammonium). Your patch measures free ammonia only. The patch basically tells you how toxic your water is to fish, whereas a test tells you how much ammonia is in the water. The patch tells you nothing useful while doing a fishless cycle. Its TAN you want to ensure is dropping to zero. Ditch the patch until you get some fish.

 

[Fro]

With a little patience, after about 6 weeks the nitrite has dropped to zero. Hurrah! Ammonia at zero also. Adding Dr Tim’s more ammonium chloride and it gets eaten and converted through to nitrate in a day. The tank appears cycled. Now to slowly add a few fish. Thanks again for the help

 

[Aiken Drum]

Good job. Well done.

Keep us informed on how things go.

 

[Jacky12]

I tried Dr. Tim’s fishless cycle and found it rather tedious. I use a cycled filter or inserts from a cycled filter instead now. I keep Xtra sponge in my sump filter as well as media in other filters. Plus I tend to over filtrate, so can easily borrow a filter from one tank & replace it with a new one in the cycled tank. I found counting out all those drops annoying