Sourcing nitrifying bacteria from China

Duty and import-control checks

Read from the UK Trade Tariff on 5 October 2026, non-pathogenic cultures of micro-organisms under 3002 49 00 20 carried 0% duty from China, with no listed anti-dumping or countervailing duty and no suspension. Heading 3002 includes cultures of micro-organisms excluding yeasts. The table describes aquaculture applications of the same tariff line.

The UK Trade Tariff attaches Veterinary control and Animal Health Certificate controls to this line. Their application to a particular non-pathogenic nitrifying formulation remains to be confirmed with the customs broker and APHA before shipment. If animal-product import rules apply, medium and high risk imports need a health certificate. Animal pathogens or carriers imported from China into Great Britain require a licence application.

Give the broker the strain list, complete formulation, carrier, animal-derived ingredients and intended use to confirm the commodity code. Do not classify a formulated preparation from its product name alone. For broader bacterial-culture sourcing, see wastewater-treatment bacterial cultures.

Specify nitrification activity in your water

Specify freshwater or marine use, the operating salinity, water temperature, pH, aeration and intended biofilter. Ask for the identity of the organisms and evidence of both ammonia and nitrite conversion. Agree an activity test in representative water, with an untreated comparison, rather than accepting a total bacterial count as proof of nitrification.

Record the liquid or other supplied form, carrier ingredients, batch activity method, storage conditions, remaining shelf life and instructions after opening. Request the source of culture-medium ingredients to help assess import controls. Environmental-hygiene products must not be presented as reducing or preventing disease in animals; review the supplier's labels and sales wording accordingly.

Worked duty example

Illustrative example, not a quote: Illustrative pilot batch of liquid aquaculture biofilter starter under 3002 49 00 20, invoiced at £4,000 free on board, with £1,500 of freight and insurance to the UK. The customs value is £5,500. Duty at 0% is £0. Import VAT at 20% is charged on the customs value plus duty, £5,500, so it is £1,100. With no duty, the only import tax is the VAT, which a VAT-registered importer can usually reclaim. The import duty and VAT guide explains each step.

Inspection checklist

Identity: match batch labels and the certificate of analysis to the agreed organisms, formulation and production site.

Activity: test retained arrival samples for ammonia and nitrite conversion under the agreed water conditions; compare results with the contractual acceptance criteria.

Transport: review temperature records against the supplier's stability evidence and inspect containers for leaks, damaged seals and unexpected swelling.

Instructions: check storage, expiry, application and after-opening directions against the approved specification; check that disease claims have not been added.

What goes wrong

A batch can meet a general bacterial-count specification without demonstrating the agreed nitrification activity. A freshwater trial may not establish performance in the buyer's saline system. Labels and appearance cannot establish activity, so agree the test method and acceptance criteria before ordering.

Unexplained carrier changes, missing ingredient origins or mismatched batch records leave the import-control assessment unresolved. Hold affected stock for review. If arrival samples fail the agreed activity test, investigate transport conditions and repeat the agreed test before using the culture in a stocked production system.

Cambridge China Bridge sources these products for UK businesses, checking the factory and the documents before shipment. See factory verification. For repeat volumes, see container programmes.