Dr. Tim's Aquatics One & Only Live Nitrifying Bacteria for Reef Aquariums

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Dr. Tim's Aquatics One & Only Live Nitrifying Bacteria for Reef Aquariums removes toxic ammonia and nitrite, instantly working to prevent new tank syndrome by establishing a biological filter in your newly set up aquarium. Use One & Only when setting up a new tank, after a disease treatment, or during water changes. This powerful solution contains no sulfur or other offensive odors.

Key Benefits
  • Prevents and eliminates new tank syndrome by instantly working to establish a biofilter in newly set up aquariums.
  • Special blend of nitrifying bacteria rapidly conditions aquarium water so there is no wait needed, you can add fish right away!
  • Naturally removes toxic ammonia and nitrite toxicity in freshwater and saltwater aquariums.
  • No sulfide or other offensive odors so you don’t have worry about overusing.
  • Helps cure live rock and has 100% natural living nitrifiers.

HAZARDS TO HUMANS: Do not freeze. Keep out of reach of children.

Special Note

  • 2-oz bottle treats up to 30 gallons.
  • 4-oz bottle treats up to 60 gallons.
  • 8-oz bottle treats up to 120 gallons.

See all items by Dr. Tim's Aquatics

  • Item Number
  • Aquarium Type
  • Fish Type
    Marine Fish
  • Product Form

100% Live Nitrifying Bacteria


Shake well before using. Best to use the entire contents at one time. Minimum dose 10 ml (2 capfuls) per 10 gallons. Cannot be overdosed. For best results, turn off protein skimmer and ozone generator (if in use) for at least 6-8 hours upon application - overnight being the best. Filters socks should also be removed, if used, for the same period of time.


What is One & Only Nitrifying Bacteria?

One & Only Nitrifying Bacteria is the latest mixture of nitrifying bacteria by Dr Timothy Hovanec. There are formulations available for freshwater aquaria, saltwater aquaria, reef, nano, and seahorse aquaria, and koi ponds and water gardens. One & Only will quickly establish a functioning biological filter in your aquarium, allowing you to immediately add fish to your tank.

What will One & Only do for me?

One & Only is designed for one job – to quickly establish a biofilter in your newly set-up aquarium so that your fish do not experience New Tank Syndrome (NTS), which is when the water contains such high levels of ammonia and/or nitrite that your fish die. One & Only does this by containing species of ammonia- and nitrite-oxidizing bacteria that prefer to live in the fish tank environment. One & Only is not a sludge buster nor will One & Only remove nitrate. One & Only will maintain ammonia and nitrite below toxic concentrations and establish a fully functioning biological filter in less than half the time of a similar but non-dosed aquarium.

How should One & Only be added to the aquaria?

Before adding One & Only to your tank, make sure the water has been dechlorinated. Research has shown that One & Only can be safely used with DrTim’s Aquatics’ AquaCleanse tapwater detoxifier. Other dechlorinators can be used but some are actually harmful to One & Only: do not use any product that contains aldehydes in its formula. UV-sterilizers and protein skimmers should be turned off before adding One & Only and remain off for 36-48 hours after dosing.It is important to shake the bottle well before adding One & Only. If you see only a clear liquid you have not shaken One & Only well enough. Pour the One & Only over the biological filter media in your biofilter. If you do not have dedicated filter media it is fine to pour the liquid into the fish tank water.

When should One & Only be added?

One & Only should be added after the tank has been set up. At this point the water should have reached the proper temperature and have been dechlorinated. Start the filter and make sure it is functioning and then add One & Only. Fish should be added within 24 hours of adding One & Only nitrifying bacteria. An alternative to adding fish is to add some ammonia to the water.

How many fish can I add to the aquarium after dosing with One & Only?

This is the hardest question to answer because every situation is different. One & Only will dramatically reduce the time it takes to establish a biofilter in your newly set-up aquarium. However, even One & Only has limits.For instance, if you set up a saltwater tank and use uncured live rock, One & Only may not be able to initially control the ammonia concentration in the water because there will be too much decay of organic matter from the uncured live rock.Or if you let every friend of your kids feed the new fish tank such that you are grossly overfeeding the tank, One & Only will not be able to maintain low levels of ammonia and nitrite.Also, some fish species are very sensitive to any amount of ammonia in the water so these fish should be added to the tank in the first 20 or so days after set-up.In general, you can add one giant danio-sized fish per gallon when initially dosing with One & Only. Feed normally and monitor ammonia and nitrite levels in the water. You might see a little ammonia or nitrite for a day or so but this will quickly disappear. You can then add more fish to the aquarium.

How is One & Only different from other bacterial additives?

One & Only Nitrifying Bacteria is different than other bacterial mixes on the market today for a variety of reasons:• It is the only mixture currently available to the hobbyist that is grown and certified by Dr. Timothy A. Hovanec,• The ammonia- and nitrite-oxidizing bacteria in One & Only are grown together as a microbial community of bacteria which means they work together more effectively.• The bacteria in One & Only are grown on a microstructure, not as “free” cells in water, which helps the bacteria stay active for a longer time period.

Does One & Only ALWAYS have to be refrigerated?

No. One & Only should never be frozen, nor should it be kept at temperatures above 95°F. Normal room temperature will not harm the bacteria in One & Only. Perhaps it is easier to think about it this way: One & Only is not like an ice cream cone. Once ice cream is exposed to room temperatures it starts to melt, and if it completely melts you have a mess and no longer ice cream. One & Only is not like this. One & Only will last for 6 months at room temperatures (65 to 85°F). At colder temperatures (around 50°F) One & Only will last one year.

How should One & Only be treated in relation to temperature?

The best way to handle One & Only is to treat it the same way you would treat your fish. You wouldn’t keep the bag of fish you just bought at the fish store in direct sunlight in your car for hours while you continued shopping nor would you let that bag of fish freeze — the same goes for One & Only. Keep One & Only in moderate temperatures and it will be perfectly fine when you get it home and are ready to use it.

What about the longer term storage of One & Only?

At a temperature of about 50°F, One & Only will be viable for one year. Each bottle is stamped on the back with the words “best used by” and then a month and year.

When should I use One & Only?

Use One & Only when setting up a new tank and after major environmental changes to your aquarium. Examples of major changes include a disease treatment with antibiotics or chemicals that are harmful to the nitrifying bacteria, after a major gravel cleaning which can disturb the bacteria on the gravel and after a failure of the filter.

Can One & Only be used for fishless cycling?

Yes, but there is no real reason to do fishless cycling with One & Only. However, if you choose to go that route you need to add ammonia to the water after dosing the One & Only because the bacteria need some source of ammonia to start growing a bigger population. Dose ammonia to an initial concentration of 2 to 4 ppm which should disappear quickly, with nitrate increasing a little then disappearing. Dose one or two more times with ammonia and after your test kits show no ammonia and nitrite, it is safe to start adding fish.

What does the lot code and date label on One & Only mean?

The lot code is just a way for us to track the manufacturing and bottling process of One & Only. The lot number does not have a special code; it is just the lot assigned to the batch of One & Only bottled at that time. The “best used by” date is the date we recommend one uses One & Only by. It does not mean that One & Only will be totally ineffective after that date, only that the efficacy of One & Only will have decayed, but using One & Only will still establish a biofilter faster than doing nothing at all.

How can bacteria live in a bottle and not die for 6 months or a year?

A common misconception about bacteria in general is that they die if they are not fed. From a human being point of view this sounds perfectly reasonable: if you don’t eat, you die. However, bacteria are not human beings. Bacteria operate much differently than people and have a variety of ways to deal with those times when resources are not available for them to grow and reproduce. Some bacteria when stressed (from say lack of nutrients) form spores and go into a resting stage, waiting for conditions to improve. Nitrifiers do not form spores but have other mechanisms to deal with nutrient deficient periods. For nitrifiers, one way to deal with stressful conditions is to form a protective “shield” called EPS. EPS stands for extracellular polymeric substances and is, in simplistic terms, an organic protective shield that research shows inhibits various organisms from attacking and breaking open the cell wall of nitrifiers. Nitrifiers belong to a very old line of bacteria (millions of years) and they have developed ways to cope with very long periods of “drought.” Because the nitrifiers in DrTim’s One & Only are grown on a substrate, they can form EPS when needed and last 6 to 12 months in a bottle.

I have a Brackish water tank – which bacteria is for me?

The choice of whether to use the Freshwater One & Only or the Saltwater One & Only bacteria in a brackish water tank depends upon the salinity (or specific gravity [S.G.]) of your water.If your salinity is less than 10 ppt (1.007 S.G.) then use the freshwater formula.If your salinity is greater than 10 ppt (1.007 S.G.) then use the saltwater formula.

Rating: 4.2 of 5 stars 11 Reviews 11 Reviews 4.3 out of 5 Stars

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82% of reviewersrecommend this product

Rating: 4.2 of 5 stars 4.3 / 5

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11 Reviews

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  • 5 out of 5 stars

    Dr Tim"s One and Only

    By DawnR on Feb 9, 2021

    The product works great, which is why I ordered it. Chewy sent me expired product. I emailed them about it and to their credit they promptly mailed me a replacement. However, the replacement bottle was also expired in OCT 2020 so I've given up on getting this product from Chewy

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  • 5 out of 5 stars

    Great product!!!!!!

    By Steven on Feb 28, 2021

    This product cycled my new 29 gallon saltwater tank in 3 days the nitrites and ammonia were 0.

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  • 1 out of 5 stars

    Arrived dead?

    By pendulum on Jul 28, 2020

    There are many great reviews of this product. Unfortunately, that hasn't been my experience. After 7 days, no drop in ammonia from 2ppm starting level, no nitrite, no nitrates. It is summer and temperature in the 90's and shipped without any temperature control. I can only assume that it was stored and or shipped in too high of a temperature and the bacterial were killed. I will be purchasing another product.

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  • 4 out of 5 stars

    Works when you get a good bottle.

    By CADreamer on Jul 8, 2020

    So it was in sale so I bought 3 bottles just in case. I'm glad I did because I used one bottle and didn't see any change in 3 days so I added a 1/4 from a new bottle and the very next morning a slight change. So I added another quarter of the bottle and again a little more change. So I added the rest. I'm now day 6 and feel it should be be cycled in a couple days. Long story short... Buy a backup in case.

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  • 3 out of 5 stars

    Works? not sure.

    By JIro on Nov 2, 2020

    Not sure if it worked. Tank is still not cycled. Ammonia level is high.

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  • 5 out of 5 stars

    This is liquid gold

    By SoFloNewBieReefer on May 2, 2020

    Dr. Tim's actually works. It turbo charged my tank's cycle. I used it in conjunction with his ammonia product to fish less cycle the tank. The cycle's establishment completed in three weeks. It was very nice to have clear instructions on how to do this. His website is very informative if you want to follow a process.

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  • 5 out of 5 stars

    First time using

    By David on Feb 27, 2020

    I used this product for the first time. I had put Reef Rock manmade live rock in a nano tank. The ammonia and nitrite levels were high. I added Dr Tim's bacteria and the levels went to zero in about 5 days.

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  • 4 out of 5 stars

    Before you buy this, see the vid!

    By alanjamesblair on May 19, 2019

    I used this on my new system. I had never done a fishless cycle and I thought it was high time. But BEWARE! What the add and the instructions do not tell you is that you need ammonium chloride to feed those bacteria. So this is NOT a one-and-done. If you don't buy the am-chlo, you'll end up in my situation, feeding an empty tank for almost a month to get the cycle going. All-in-all, I like this product, but I would not buy it again without the am-chlo and I think that should be mentioned in the description.

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  • 5 out of 5 stars

    Cycling stage

    By Vince on Aug 18, 2019

    Great product to use for cycling your reef tank great results

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  • 5 out of 5 stars

    Dr Tim’s one and only

    By Marshall on Jun 6, 2019

    Definitely helped jumpstart my saltwater tank. Got the needed bacteria cycle moving right along

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