Dr. Tim's Aquatics

One & Only Saltwater Live Nitrifying Bacteria

Grouped product items
2oz One & Only Live Nitrifying Bacteria - Dr.Tim's

SKU: 210876

In stock

$16.06 $18.89

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4oz One & Only Live Nitrifying Bacteria - Dr.Tim's

SKU: 210877

In stock

$28.55 $33.59

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8oz One & Only Live Nitrifying Bacteria - Dr.Tim's

SKU: 210878

In stock

$46.66 $54.89

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16oz One & Only Live Nitrifying Bacteria - Dr.Tim's

SKU: 210879

In stock

$86.27 $101.49

- +

Instantly create a bio filter in saltwater aquariums that can eliminate new tank syndrome and remove toxic ammonia and nitrite without any sulfurs or odors.

Perfect for fishless cycling new aquariums, especially if used with Dr.Tim's Ammonium Chloride.

Four Sizes Available:

  • 2oz - up to 30 gallon aquariums
  • 4oz - up to 60 gallon aquariums
  • 8oz - up to 120 gallon aquariums
  • 16oz - up to 240 gallon aquariums


Dr.Tim's One & Only Live Nitrifying Bacteria for saltwater tanks is widely used throughout the hobby and can be used to help prevent common issues with new tanks while helping stabilize existing tanks. Dr. Tim is considered to be one of the premier authorities on marine nitrifying bacteria in open and closed systems. One & Only contains millions of live nitrifying bacteria that will help quickly establish a biological filter in your aquarium allowing you to add fish almost immediately. 

  • New Tanks
  • After Water Changes
  • Adding New Fish
  • After Treatments


Using Dr.Tim's One & Only is very simple. You should first make sure that your tank is dechlorinated which is critical. If you do find the presence of chlorine, you will need to use a dechlorinator that does not contain aldehydes which can be harmful to the bacteria you will be adding. Turn off any protein skimmers or UV sterilizers and keep them off for up to 48 hours after the addition of One & Only Bacteria. 

Shake the bottle very well; the liquid should not be clear. If the liquid is clear, you have more shaking to do! Pour the recommended dose directly onto your biological filter media for the best results. If you do not have a dedicated biofilter, you can just pour dose directly into your aquarium water. 


For New Tanks

Add Dr.Tim's One & Only to dechlorinated water after the aquarium has reached the proper temperature, and any filtration components are checked and functioning properly. Once One & Only is added to the tank, fish should be introduced within 24 hours. Without fish, no organic waste is generated, which the bacteria require. If you are not ready to add fish, you can add small amounts of ammonia to the water. 

It is recommended to use Dr.Tim's Ammonium Chloride Solution to produce ammonia for the bacteria to consume and convert. Ammonium Chloride will let you cycle your aquarium without having to add a sacrificial fish or any foods giving you complete control of how your tank cycles. 


Temperature Sensitive - We recommend shipping Dr.Tim's One & Only when outside temperatures range from 40°F to 80°F. In the middle of hot summer or cold winter months we highly encourage expedited shipping methods. 


Refrigeration not required - Never freeze or store in temperature over 95°F - Stable for up to 6 months at room temperatures and up to 1 year at temperatures ranging 40°F to 50°F.


Recommended for aquariums with a salinity over 10ppt or 1.007sg


Cycling a new aquarium or need to combat Cyanobacteria or other algae?

Get your free download of Dr. Tim's Aquatic Recipes for Success

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Product Questions

At the moment where I live the average temp is 45 degrees fahrenheit, would the bacteria in this product survive being shipped on a truck in cold weather?
Question by: Raymond on Nov 11, 2022, 12:22 AM
Hi! I would say it should be fine, as we insulate our packages very well. As long as the bottle does not come frozen solid your bacteria culture will still be alive. If you have any questions please do not hesitate to reach out by email or by giving us a call.
Answer by: Adam Malik (BRS Staff) on Nov 15, 2022, 4:58 PM
Why do some bottles say use one cupful and some say two capsules ( same size bottles ).
Question by: john muller on Dec 30, 2018, 2:08 PM
Thanks for contacting BRS!
It is possible that the manufacturer changed the dosing instructions, but we recommend dosing what the bottle you have says. Have a great day!
Answer by: Noah on Jan 2, 2019, 5:07 PM
Can this be used on freshwater?
Question by: Cris on Nov 25, 2017, 9:33 PM
There are different bacteria active in freshwater aquariums, and Dr. Tim's does offer this product. As we specifically cater to saltwater aquarium needs, we only offer the saltwater version.

Hope this helps!
Answer by: Zack on Nov 25, 2017, 11:10 PM
Does this come with something to feed the bacteria of you don't add fish right away?
Question by: Thomas Guarino on Jun 8, 2017, 7:57 AM
This is a bacterial starter supplement only and does not include a food source. We are bringing in the Dr. Tim's Ammonia product for those who wish to cycle their tanks without fish.

Happy reefing!
Answer by: Zack on Jun 13, 2017, 9:23 PM
Does the kit come with ammonia? TIA
Question by: Davide Lodovichi on Jun 1, 2017, 8:04 PM
This product is the bacterial additive only and does not include an ammonia food source. We are in the process of bringing in Dr. Tim's pure Ammonium chloride and should have that available very shortly for those who wish to cycle their tank without livestock!

Happy reefing!
Answer by: Zack on Jun 8, 2017, 10:44 AM