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Translated in Dutch by John de Lange
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2.8. Bacteria-in-a-bottle

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Author : David Bogert

Published :

Time To Read :
5 minutes
Difficulty : Level 6

Excerpt :

Bacteria-in-a-bottle products that claim to cycle an aquarium in one day simply do not work.

There are a whole series of “quick start”, “starter bacteria”, “nitrifying bacteria”, “stabilization systems” and “bacteria-in-a-bottle” products that claim to enable one to do the following:

  • “Add Fish Immediately”
  • “Safe Immediate Introduction of Livestock”
  • “Allows Instant Addition of Fish”
  • “Avoid New Tank Syndrome”
  • “Prevents New Tank Syndrome”
  • “Rapidly Cycle Tanks”
  • “Allows Immediate Introduction of Fish”

Three tests were run on eleven popular bacteria-in-a-bottle products (seven of these were replicated twice for accuracy). Ten other treatments were used. All the tests were run with ammonia (ammonium chloride in ammonia solution). The first two tests had a phosphate fertilizer added at the beginning of the cycling. In the first two tests composted cow manure, brown gunk from an aquarium filter and garden soil took 8 to 12 days to cycle, the commercial “bacteria-in-a-bottle” products, and the four controls (no treatment) took 26 to 46 days to cycle.

Placidochromis Electra Black Face Gome
Placidochromis Electra – Black Face Gome

Surprisingly a third test showed that the addition of phosphate fertilizer is very important if one is cycling with ammonia.

Test of Bacteria in a Bottle Products

The three tests can be put into a table format:

TreatmentDays to cycle Test 1 with phosphate addedDays to cycle Test 2 with phosphate addedDays to cycle Test 3 without phosphate added
Manure compost8812
Sponge filter gunk121014
Black soil121426
Dr. Tim’s One and Only263422
Glosso Dry Bacteria3046
Seachem Stability323848
No treatment #1324036
Fluval Cycle342856
Tetra Safestart362846
No treatment #2364052
Microbe-lift Special Blend36
Microbe-lift Nite Out3840
Frizyme Turbo Start383256
API Quick Start424448
Aqueon Pure Balls42
Test of bacteria in a bottle for aquariums

The tests proved that bacteria-in-a-bottle products do not help establish a cycle any faster than adding nothing will (there were a total of four “nothing” tests run which came out the same as adding bacteria in a bottle products). None of them will do anything to “avoid new tank syndrome”. And if one wants to avoid adding fish during the ammonia and nitrite spikes of cycling, these products will not allow one to “add fish immediately”.

Placidochromis phenochilus Gissel
Placidochromis phenochilus Gissel

Note the “black soil” referred to was from potted plants and the garden. It was not the commercial potting soil sold in garden stores. Most commercial packaged potting soil is sterilized and will not provide any benefit to cycling.

The addition of phosphate turned out to be very interesting. It helped the cycle time to add phosphate. It also appears that Dr. Tim’s One and Only brand of bacteria has phosphate in it. And it appears manure compost and sponge filter gunk have significant phosphate in them but black soil does not have phosphate. But more tests would be necessary to firm up that data.

Note that this test was deliberately kept very simple so that anyone can easily duplicate it if they want to. A rigorous scientific test under laboratory conditions cannot be replicated by any hobbyist so that was not done. This test was not designed to be published in some scientific journals. But the test results were analyzed using the very powerful JMP statistical analysis software and the conclusions were irrefutable.

image of an aquarium fish Buccochromis rhoadesii female
Buccochromis rhoadesii female


This study conclusively proved four things and only four things:

  • Bacteria-in-a-bottle products do not speed up the aquarium cycling process, with no significant difference being seen between bacteria in bottle products and aquariums cycled with nothing added.
  • Compost, brown gunk from an established filter, and soil do speed up the aquarium cycling process significantly.
  • Cycle time is reduced by the addition of phosphate at the start of the cycle.
  • Dr. Tim’s One and Only beneficial bacteria-in-a-bottle did have some statistically positive effects on cycling. This may be due just to dumb luck. The bottle of Dr. Tim’s might have been very “fresh”.

One must caution against reading anything else into the study. The JMP statistical software showed ONLY that these four conclusions can be drawn at a 95% confidence level.

For a far more in-depth analysis of bacteria in a bottle products and this test go to this link:

2.8.1. Bacteria in a Bottle in Depth

picture of an aquarium fish Protomelas Spilonotus Tanzania
Protomelas Spilonotus Tanzania

Belief Perseverance Effect

Now there is a psychological phenomenon called “belief perseverance effect” which is very strong. “Belief perseverance effect,” says that if someone buys something, and especially if someone pays a lot of money for that something, even when presented with evidence they made their purchase in error, a normal person will rationalize and support their own decision. There is no way any evidence, testing, or science can penetrate the walls that the belief perseverance effect puts up. So we won’t try.

“Nothing dies harder than a lie that people want to believe”


The chart above was put on Facebook and one commenter came back with what is a typical comment:

“I’ve used Stability with a brand new tank and canister filter and cycled in 14 days with fish in.”

Fish poop is filled with tons of beneficial bacteria. So this hobbyist simply seeded his filter with fish poop. The Seachem Stability had nothing to do with the cycle. But of course, no one noticed this little fact.

OB Peacock
OB Peacock

Here is another actual comment about the same chart: Hendrix Ralston to David Bogert 3-26-2022

“Yeah, I don’t trust those numbers. I’ve used Frytzyme 7 and 9 on all tanks I’ve set up in the past few years and have always had them cycle out in no more than a week.”

What is missing here is the following sentence:

“I’ve used the same cycling process without the Fritzyme and it took three to five weeks to cycle the aquariums.”

There are many reasons a “cycle” can happen very fast: fish poop in the tank, plants in the tank, carbohydrate-rich fish food used to cycle the tank, defining the end of cycling differently, etc. Without using “controls” any test is meaningless. And it should be noted that Fritz has a very active “fake account” presence on Facebook.

Normally marketing hype does not harm the fish. But if someone believes this “instant cycling” claim and adds a ton of fish at aquarium start-up together with some bacteria-in-a-bottle, this hobbyist, in very rare instances, might lose all their fish. But so be it!

Placidochromis Electra Londo
Placidochromis Electra Londo

There is another “bacteria-in-a-bottle” series of products. These products supposedly “reduce and eliminate sludge” in an aquarium. These are all complete scams. These products are reviewed at this link:

2.8.2. Sludge Reducing Bacteria