Fishless cycle help

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Aquarium Advice Apprentice
Nov 24, 2023
Hi this is my first post. I have a 2.5 gallon tank with heater (80 degrees), bubbler, light, and betta filter. I put 2 cartridges in the filter and the water flows well, hoping in the future I can change one at a time to not lose a lot of beneficial bacteria. I read that’s where a lot of them live. Gravel substrate and fake plants/plastic decorations. I used to have a guppy in the tank 3 months ago that passed after a year and have been trying to get the tank ready again either for a betta or some snails and shrimp since I think having a tank this small is very hard for fish and for me to keep the water clean enough for them.

I have been trying to fishless cycle by doing water changes and using conditioner and quick start and had been consistently at

Ammonia 1
Nitrite 0.5
PH 6.5-7
Nitrate 0

I was discouraged that fishless my water parameters were not good enough yet. Then I read I need to ramp the ammonia up more than that by adding food which I did a week ago. And the beneficial bacteria will build up.

Ammonia 2
Nitrite 0.75
Ph 6
Nitrate 0

Ammonia 4
Nitrite 0.75
PH 6.5-7
Nitrate 0

Ammonia 4
Nitrite 0.75
Ph 8.5
Nitrate 0

Is it bad my ph is all over the place? Is my ammonia too high? Do I need to add plants if I do get shrimp or a betta? Do I need to suck it up and get a bigger tank?
Thanks so much for the help and advice!!
How are you dosing ammonia?

How long ago did you start?

A fishless cycle typically takes 6 to 8 weeks. The earliest date on your post is 4 days ago.
How are you dosing ammonia?

How long ago did you start?

A fishless cycle typically takes 6 to 8 weeks. The earliest date on your post is 4 days ago.

I started 3 months ago after my last fish passed but had been doing periodic water changes. There was about 1ppm of ammonia the whole time. A week ago I just started adding fish food in a net to dose ammonia. I put a couple pinches in.
For now don't add any more fishfood. Wait for what ammonia you have added to cycle out. If the ammonia continues to rise, thats the fishfood decomposing, and you should do a water change to get it back down to 2 to 4ppm.

Fishfood isnt a good way to dose ammonia. Its very difficult to judge how much food to add to get ammonia up to a level it needs to be. Dosing actual ammonia or better still an aquarium specific ammonium chloride product like Dr Tims Ammonium chloride is an easier way to ensure you have the right ammonia concentration.

2 pinches of food in a 2.5 gallon tank sounds like a lot. If you are doing fish food as your ammonia source then as much food as that 1 guppy ate in a day, every day, until you can no longer detect ammonia or nitrite. So 2 or 3 flakes/ pellets per day.

I wouldnt worry about measuring pH or nitrate until your cycle completes. They will be all over the place until the processes settle down and the results will just confuse you if they arent what you expect.

Can you test your tap water and let us know the results.

And, 2.5g is a bit small for any fish. Would make a nice shrimp tank though. Put a piece of anubias in there and some java fern so the shrimp have a nice, natural place to live.
Ok thanks! I tested some tap water that I had sitting out for >24 hours.
Ammonia 0.5
Nitrite 0
Nitrate 0
Ph 9
When I test the ph directly from sink when it hasn’t been sitting out it’s 7.5.

Can the plants you suggested do well in gravel? Or would I need a different substrate?
For a start, your water must be treated with chloramine rather than chlorine. Chloramine is chemically bonded ammonia and chlorine and is more stable than chlorine, but unfortunately this means your tap water contains ammonia. You need to make sure your water conditioner treats chloramine (most do, some dont). It also explains why you had ammonia in your tank before you started adding fish food.

So water changes will add ammonia, rather than reducing it, and during your fishless cycle those water changes made it appear that you were getting nowhere. When you are cycled, the cycle will quickly remove the ammonia. So dont do water changes until the ammonia you already have is cycled out.

As for the plants, neither of them need substrate at all. You can keep them in a bare bottom tank if you like. Just superglue or tie the java fern or the rhyzome of the anubias to a rock, piece of driftwood, or other decoration and place it in the tank.
Your tap water pH is very high. Its getting more alkaline as it sits, so that suggests there is high amounts of CO2 that acidify the water, and as it offgases as it sits the pH increases. You might want to consider using bottled spring water instead of tap water.

You only have 2.5g tank so it shouldn't be too expensive to buy a gallon of spring water once a week for your water changes.
Wow this is all really helpful. I really appreciate the answers. I will pick up Dr Tim’s, some plants, and spring water and will keep you posted how my cycling process goes.
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 and nitrite. Whenever your ammonia drops below 1ppm redose it back to 2ppm. Nitrite causes false positive nitrate readings, so no point in testing for nitrate until your cycle is complete. False positive results will just confuse matters.

You should start to see nitrite and 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.

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, so now test for nitrate. Do a big water change to get this 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.
Still holding steady at 4ppm ammonia and 0.5 nitrite. Haven’t had to dose Dr Tim’s yet. Added more tap water for what evaporated off. My conditioner does treat chloramides. Will keep you up to date as I go.
Some green algae starting to form on some of the decorations

Recheck your nitrATE test. Green algae is caused by light and food ( the food is either nitrates or phosphates. ) While neither is directly related to your nitrogen cycle, if there are nitrates in the tank not coming from your source water, it would mean your "cycling" process is well under way and your nitrite level should be zeroing out shortly if it hasn't happened already. (y)

You can control the green algae by reducing the amount of light going into the tank. (y)
So update. I have been dosing 8 drops of Dr tims every other day for the past week. That gets my ammonia up to 2. 24 hours later I’m down to 0.5. My nitrite has been holding flat at 0.5 for a week. Just checked nitrates for first time in a while and it’s more yellow than orange so somewhere between 0 and 5. There’s a decent amount of green algae bloom so I would have thought my nitrates would be higher at this point. Plus my ammonia is definitely converting to nitrite. Why isn’t my nitrite off the charts yet? I just cleaned my filter cartridges with tank water.
Because your nitrite is being converted to nitrate. The nitrate test is very difficult to get an accurate reading from. If its the API liquid drop test you have to really shake the heck out of bottle #2. Like bang it on the countertop. Really abuse the bottle to get the reagents unstuck from the side of the bottle and into the liquid.

But really, until your cycle is finished dont even bother testing for nitrate. The presence of nitrite will also throw off the test result, and whatever result you get will just be confusing.
I have the Topfin freshwater aquarium test kit. Good to know on bottle 2.

By fully cycled you mean dosing with my 8 drops and ammonia and nitrite being 0 24 hours later?

I have 2 filter cartridges in my filter. When I’m cycled I want to only replace one at a time so I don’t shut the process off but for now leaving them in and they are getting pretty dark. Should I be vacuuming substrate at all or any other cleaning during this process?

I’m also going to add the real plants in once I’m fully cycled.


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If you are using dr tims ammonium chloride, 4 drops per gallon should raise ammonia 2ppm. So 8 drops in your 2.5g is about. So yes, if you add 8 drops and the following day see zero ammonia and nitrite you are cycled. Nitrate is irrelevant really.
Going back to your filter cartridges, yes change one at a time, and only change them when they are pretty much falling apart. Maybe try and get into a routine, change 1 this month, the other the following month. See how long they last, if you can go longer do so. Every week rinse them in dechlorinated water so they last longer.
Update. I think I over added ammonia and I have been at 4 ammonia, 0.25 nitrite the last 4 days. Does that set me back to the beginning of the cycle again?
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