Fishless cycle, nitrites bounced back up. Is that normal?

[AzureJasper]

Hi! We’re new to the aquarium world, gifted my 9yo with a 120L tank (3 feet long). We’ve been doing a fishless cycle and I thought it was don but the nitrites have gone back up to 0.25ppm. Wondering if anyone can offer some advice. We’re a month in and I’m amazed how patient a 9yo can be (he’s wanted a goldfish for a long time).

Details: 120 litre tank (3feet long), fine gravel substrate, many rocks, many live plants (most growing well), Aqua one 800 canister filter filled with extra bio noodles, heater running set to 26c (with thermometer in there to confirm it’s heating).

Started the cycle with api QuickStart, api water conditioner and dr Tim’s ammonia drops. Added live plants from the start too (Anubias on driftwood, water wisteria, aluminium, Java moss, Java fern and a couple of others, along with some larger rocks, all from a local fish shop).

Began with ph 7.5, ammonia 0, nitrites 0, nitrates 0 to 5.
Dosed with dr Tim’s ammonia, along with QuickStart.

Testing water with api master freshwater kit.

On day 11 had first drop in ammonia and first registered nitrites.

On day 23 had the nitrites come down to zero (after being over 5ppm for a day or two at their peak, then sat at 1ppm for a few days before coming down to zero). At the same time ammonia of 2ppm was being consumed daily, and nitrates began to climb (over 40ppm). Also at this time the ph dropped from steady 7.5 to 6.4

It stayed steady with ammonia and nitrites zero for a 3 days (with 1 to 2ppm of ammonia added daily, testing to 0 in 24hrs) and ph 6.4,
but now we’ve seen ammonia not getting back to 0 in 24hrs (0.5ppm)
and nitrite 0.25ppm again.
Nitrates 160ppm.

Am wondering if this is normal for nitrites to climb back up a little? Everything I’ve read says once nitrites hit zero we should be cycled.

 

[Colin_T]

Do a massive (90-100%) water change using dechlorinated water. This will reset the pH, GH and KH and then try adding some ammonia. The beneficial filter bacteria use KH (carbonate hardness) and the KH helps stabilise the pH. If the pH has dropped, you have run out of KH and a big water change will replace the lost minerals and allow the bacteria a chance to keep going.

 

[AzureJasper]

Thanks for the reply

Do a massive (90-100%) water change using dechlorinated water. This will reset the pH, GH and KH and then try adding some ammonia. The beneficial filter bacteria use KH (carbonate hardness) and the KH helps stabilise the pH. If the pH has dropped, you have run out of KH and a big water change will replace the lost minerals and allow the bacteria a chance to keep going.

Thanks Colin, I’ll try that. Will pick up a siphon/hose today and give it a go. We did add some “KH powder and GH conditioner” that the shop sold us, forgot about that as went not testing those parameters. But yeah, the ph dropped as the nitrites/nitrates began to go up.

 

[Aiken Drum]

Whats happening isnt usual, but its what happening.

Do a big water change, or multiple water changes, to get that nitrate down to a safe 5 to 10ppm. Redose ammonia and see how long it then takes for you get to zero ammonia and nitrite. If its 24 hours then i would call it cycled. Even if it takes 48 hours adding a small goldfish will be perfectly safe if you continue to monitor water quality and change water if you see anything untoward.

A small goldfish will produce nowhere near the amount of ammonia you have been dosing. The amount of microbes you have grown will gradually die off to match the amount of waste your fish produces, then as the fish grows they will grow in number to match the increased amount of waste a larger fish produces. Just continue to monitor things until you are confident things are stable.

 

[pauldadams1984]

Hey jesper. Is there any reason in particular for the 26 degrees?

Goldfish will handle that fine but I believe room temperature is optimum. Around 20-24.

Although, changing temperature whilst cycling might be more hassle than it's worth.

What's others think?

 

[Colin_T]

goldfish will be fine at 26C but do need a cool period for several months over winter. You can turn the heater off for this and then just let the temperature rise naturally in spring.

 

[Aiken Drum]

Is there any reason in particular for the 26 degrees?

26c is a good temperature to undertake a fishless cycle. The microbe growth rate is faster at higher temperature than most aquariums are running at. 28c is considered the optimum temperature for cycling a tank. With a fishless cycle you dont have to worry about the water being too warm for any fish, so just crank it up and drop it to a suitable temperature once your cycle is complete.

 

[AzureJasper]

Hey jesper. Is there any reason in particular for the 26 degrees?

Goldfish will handle that fine but I believe room temperature is optimum. Around 20-24.

Although, changing temperature whilst cycling might be more hassle than it's worth.

What's others think?

Initially had the heater set to 20c, but read somewhere that the beneficial bacteria grow faster in warm water, so bumped the temp up after about two weeks. Of course there’s no fish yet, doing the cycle with ammonia chloride liquid.

 

[AzureJasper]

goldfish will be fine at 26C but do need a cool period for several months over winter. You can turn the heater off for this and then just let the temperature rise naturally in spring.

I live in the blue mountains, very cold in winter here, I thought I’d need to keep the temp up above 20c at least? We often get in the negatives over night and it’s an old house with no insulation.

 

[AzureJasper]

26c is a good temperature to undertake a fishless cycle. The microbe growth rate is faster at higher temperature than most aquariums are running at. 28c is considered the optimum temperature for cycling a tank. With a fishless cycle you dont have to worry about the water being too warm for any fish, so just crank it up and drop it to a suitable temperature once your cycle is complete.

Thanks, this was my thinking too, after reading similar online somewhere.

 

[AzureJasper]

Thanks for the advice and input everyone. I’m doing an 80% + water change now

 

[Colin_T]

I live in the blue mountains, very cold in winter here, I thought I’d need to keep the temp up above 20c at least? We often get in the negatives over night and it’s an old house with no insulation.

Goldfish can live in water that is near freezing. As long as the water doesn't freeze solid, they are normally fine. The average house temperature in winter is fine for goldfish even if it's an old house.

Fantail (double tail) goldfish do better in slightly warmer water but anything from 10C and up is fine for all goldfish and healthy fish kept outdoors all year round can survive temperatures of 1C over winter.

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If you have a heated aquarium in a cold house, you can insulate the base, back and sides of the tank with 1-2 inch thick polystyrene foam sheets. Just use some tape to hold the foam on the outside of the aquarium.

A coverglass on the tank will also help trap heat. Use glass that is 4, 5 or 6mm thick because it is less likely to chip than thinner glass (2 or 3mm thick) that is commonly sold at pet shops.

And if you own the place, insulate it asap to keep warm. Or talk to the landlord and get them to insulate it for the environment. I'm sure there are laws now saying houses must be insulated so maybe check into that. If a government department says it needs to be insulated, the landlord will have to do it.

 

[AzureJasper]

It’s the day after the big water change (about 80%), dechlorinated the fresh water and added GH and KH powder;
Tested tank after adding fresh water:
Ph 6.8
Ammonia 0
Nitrite 0
Nitrate 20ppm
Added 1ppm ammonia (tested 30min later as 1ppm)

9hrs later ammonia 0.5ppm; nitrite 0.25ppm.
Now 21hrs after water change/dosing ammonia tested:
Ph 6.8
Ammonia 0
Nitrite 0
Nitrate 40ppm

At this point I’m thinking we’re cycled, at least enough for a small goldfish. I guess I should change more water first though, to get the nitrate down right? Thanks everyone

 

[Aiken Drum]

I guess I should change more water first though, to get the nitrate down right?

Ideally less than 10ppm. Continue to monitor things until you are confident everything is stable.

 

[AzureJasper]

Follow up question: so far I’ve been testing the water about every 24hrs, today we tested this morning after dosing ammonia the evening before, and it had nitrite and ammonia both zero. We thought to be sure we’re cycled before adding fish we’d do another dose of ammonia this morning and check it again tomorrow morning (after 24hrs); but being impatient I’ve tested it again now , 5hrs later, and nitrite 0.25, ammonia less than was dosed (lighter green than 1ppm on the api test).

Question is, for a cycled tank, will nitrites rise slightly (to almost 0.25ppm) a few hrs after adding ammonia?
Obviously I’ll check again after 24hrs and if zero ammonia & nitrite I’d assume cycled?

 

[Colin_T]

If you have enough beneficial bacteria to convert nitrite into nitrate, then you shouldn't get much (if any) nitrite reading. The bacteria that eat nitrite will convert it into nitrate as soon as nitrite becomes available. So ammonia gets converted to nitrite, and nitrite starts to be converted to nitrate as soon as it's available.

 

[AzureJasper]

So at no point should I see any nitrites at all when properly cycled, even after adding ammonia? I thought we were there… after seeing zero after 20+hrs. Thanks, this is really helpful

 

[Colin_T]

If you add x amount of ammonia to a tank, yes you will see an ammonia and probably a nitrite reading. However, you don't normally get a high ammonia reading in an established aquarium unless something big dies or there is a heap of uneaten food rotting in the tank.

Most aquariums have a low level (less than 1pm) of ammonia produced during feeding and significantly less when the fish aren't eating. The ammonia is normally produced on a slow but steady basis so the bacteria can easily consume any that is there.

The ammonia that is added to an aquarium to cycle the filter is at a much higher level than would be found in any average aquarium. The idea of cycling a tank is to build levels of beneficial filter bacteria so you can add a full load of fish immediately after it has cycled. If you add 3-5ppm of ammonia, most of the bacteria that is produced during the cycling process, will gradually die off after fish have been added because there isn't enough ammonia being produced by the fish to feed all the bacteria that has grown.

 

[Aiken Drum]

With a well established cycle, water should be coming out of the filter free of ammonia and nitrite. There will always be some ammonia in the water in your tank because fish are constantly producing it, but it would normally be such a small amount that your test kit isnt good enough to detect it. You might get a detectable level if there is more than normal amounts of ammonia, for instance after feeding or if something dies and starts to decompose.

Ive had instances at the end of fishless cycles where 2ppm has cycled out in 10 or 15 minutes, once there has been a complete turnover of the water through the filter. Its unlikely the microbial colony would stay at level for long after introducing fish because a tank full of fish won't produce anywhere near as much ammonia as you dose during a fishless cycle. If you took all the ammonia produced by a fully stocked tank of fish it would probably be enough to raise ammonia to 0.5ppm if dumped in the tank in one go.

You arent really trying to cycle out 2ppm of ammonia in 24 hours. You want to be able to cycle out the trace amounts of ammonia your fish produce immediately as the water goes through the filter. Its generally agreed that being able to cycle out 2ppm in 24 hours is enough microbes to cycle out trace amounts immediately. This level has been arrived by years of trial and error.

 

[Andy Sager]

While the others have covered what's happening, I'll add this, the bacteria bed/ biological filter is a living breathing organism of 2 or more microbes that grows and shrinks to the amount of ammonia being produced. The ammonia is converted to Nitrites which is then converted to Nitrate. You may have just hit the small " sweet spot' where the ammonia had been converted and before the nitrite was which was why you got that reading. You may also be getting that reading because some test kits show nitrite when it's really part of the nitrates that it's reading.
2 things you can do, 1) test the water from the outflow of the filter ( if it's a HOB style) or from the return tube if it's a canister style. If you are getting a nitrite reading from there, it usually means that there are not enough microbes yet to consume the amount of nitrites produced yet but under " normal" circumstances, they reproduce quickly so you shouldn't see any nitrites within 24 hours ( or less.) 2) (Assuming that you have no nitrites after 24 hours) Now that you have done 2 PPM ammonia, try adding less ammonia ( 1 ppm) and see if you still get a nitrite reading 5 hours later. You shouldn't get any reading since you have enough biological to reduce the nitrites in 24 hours. If you do get a reading, take a sample of that water to your LFS and have them confirm your readings.

And FYI: This is not something that happens with fish in cycling as the microbes grow immediately to the volume of ammonia and nitrites present. The thing is this takes months to happen.