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JBL Denitrol - Complete Beneficial Bacteria (100/250ml) 1 review

by JBL
SKU J23061
JBL Denitrol (complete beneficial bacteria)
  • For aquarium water to suit both fish and plants: when setting up a new aquarium, water changes and after fish diseases for freshwater and saltwater aquariums, turtle and shrimp tanks.
  • Shake the bottle well, measure the right amount in the dosing lid and evenly distribute in the aquarium.
  • Live bacteria with enzymes for the rapid breakdown of pollutants.
  • Healthy water, healthy fish: breakdown of fish excrement and other waste by means of special enzymes and cleansing bacteria.
  • Contents: 1 bottle Denitrol.
  • Use: 10 ml for 20 l water during initial setup and disease, 10 ml for 300 l water during water change.



Nature at home – home for fish and plants

  • Fish need to be as comfortable in the aquarium as they are in nature.
  • When setting up an aquarium and during partial water changes the aquarium needs sufficient bacteria to be biologically cleaned and to quickly break down harmful substances.
  • Bacterial starters contain highly active beneficial bacteria which break down the ammonium/ammonia and nitrite as well as the fish excrements and other waste in the water.

Advantages of the JBL bacterial starters

  • Live bacteria, breakdown of ammonium/ammonia and nitrite through active bacteria, breakdown of fish excrement and other waste.
  • 8 complementary bacteria cultures to break down protein (heterotrophic bacteria), ammonium and nitrite.
  • Gradually start with the stocking of fish in newly set-up aquariums immediately after adding JBL Denitrol.



  • The opinions vary as to whether fish can be added as early as one day after the aquarium set-up. Microbiologists have observed that bacteria reproduce very slowly in a new aquarium when there is no water pollution (nutrition for bacteria).
  • But if you add fish the next day without using a bacterial starter, problems with ammonium/ammonia can occur because the bacteria initially reproduce too slowly to keep pace with the production of pollutants.
  • When using JBL Denitrol (15 minutes after adding JBL Biotopol) higher quantities of bacteria are present.
  • The next day, after the first fish have been added, there is food for the bacteria and they start to reproduce. This will make sure that there are always enough bacteria, so that neither ammonium/ammonia or nitrite will become a problem.



What happens, when Denitrol has been dosed and the animals aren’t added until several days later?

> Without an immediate insertion of animals the cleansing bacteria added with Denitrol will die from lack of food within a short period. If you insert the animals after several days (contrary to these instructions) problems will occur with ammonium/ammonia and nitrite.

If you insert the first fish immediately after adding Denitrol the cleansing bacteria will receive nutrition and start to reproduce. This ensures that there are enough bacteria available from the start to prevent problems with ammonium/ammonia or nitrite.


How many fish, shrimps or snails may be inserted after 15 minutes?

> After adding JBL Denitrol into initially set up aquariums you can add 1 cm fish per 2 litres of water. You can raise the fish stock after 14 days.


May I feed the animals on a regular basis during the first three weeks?

> No, you need to feed them very sparingly with maximum 25% of the usual amount. The bacteria are adapting to the current water load and may not be overstrained. A slow increase allows the bacteria a stable adaptation to their environment.


Can you overdose Denitrol?

> With Denitrol you can add up to five times the amount of a dose.


If I want to add JBL Denitrol to my aquarium, do I need to switch off the UV-C device?

> Yes, this would be useful. The bacteria need a little time to settle on the substrate. Until then they are floating freely in the water so that the UV-C radiation can kill them off. It is therefore recommendable to switch off the UV-C clarifier for a day.


How are the filter bacteria (nitrobacter) preserved in the bottles? How can the bacteria survive inside?

> The bacteria in the products are contained in a nutrient solution which meets the "minimum requirements", as full-scale metabolism would shorten the shelf life. As long as the bottles are in their original packaging and stored at temperatures between 4-35 °C the shelf life is 18 months.

If the liquid is clear or has occasional small brownish flocks, the product is fine. The smell should be barely discernible. If the liquid smells of rotten eggs or if it contains black flakes, the product is no longer suitable for use.


Despite JBL Denitrol, the nitrite level has not dropped.

> In order to answer this question, we would need to know the current nitrite level and how it has developed in the course of 4 hours after feeding. If the nitrite levels are high, an inhibition of the bacterial decomposition of nitrite may occur.

In this case, the following procedure is recommended:

1) Do a large water change in accordance with the nitrite level - at least 50 % if it is over 1.0 mg/l - in order to decrease the current nitrite level.

2) Add a large dose of JBL Denitrol to the tank, around 250 ml per 150 l of tank water. Aerate the tank or set the filter outflow so that it creates enough turbulence to bring in oxygen. The whitish cloudiness caused by the bacteria will disappear within a few hours and the bacteria will then quickly start processing the ammonium/ammonia and nitrite.


Do the "filter bacteria" pose a risk to sensitive persons, as they could potentially be transmitted by air?

> No, these bacteria are generally harmless to humans.

They can not get into the air, as nitrifying bacteria are generally substrate bound and bound to a medium that is aqueous to at least moist.


Do I have to turn off the UV clarifier when I add JBL Denitrol to my aquarium?

> Yes, this is necessary. The bacteria need a little time to settle on the substrate. Until then they are floating freely in the water so that the UV-C radiation can kill them off. It is therefore recommendable to switch off the UV-C clarifier for 48 hours.

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Filter Reviews:
Teck Y.
Singapore Singapore

JBL denitrol starter

Only requires half a cap of solution for my 1.5 feet tank. Used it once and I can see that my water has turned less cloudy. Price was OK for a small bottle. Can use for a year I think for my 1.5 feet tank

East Ocean Aquatic JBL Denitrol (complete beneficial bacteria) Review