NT Labs Koi Care - Formaldehyde

Item: 151

MPN: 00091

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250ml NT Labs Formaldehyde
Was £12.99 Now £10.99 (In stock)
500ml NT Labs Formaldehyde
Was £19.99 Now £16.99 (In stock)
1ltr NT Labs Formaldehyde
Was £30.99 Now £24.99 (In stock)
2.5Ltr NT Labs Formaldehyde
Was £48.99 Now £39.99 (In stock)

Product Description


NT Labs Koi Care - Formaldehyde



White spot, TrichodinaCostia and Chilodonella.


When to use? When fish show symptoms of a parasitic infection, including white spots along the fins and body, flicking and rubbing, gasping at the surface, or an opaque film over the body.

Formaldehyde is highly effective at treating parasites due to its ability to penetrate through the mucus layer, reaching those parasites which would otherwise be protected from alternative bath treatments. It can also be used in conjunction with Malachite to treat protozoan parasites more effectively.


How to use?

  • Test your water quality using NT Labs Test Kits.
  • Mix the appropriate dosage in a clean bucket of pond water, pour evenly over the surface of the pond and leave for 7 days. Switch off UV filtration for 5 days. Aerate the pond well during treatment.
  • If you feel a repeat dose is necessary, check your diagnosis carefully using the Diagnosis Tool; a different medication may be more suitable. Allow 7 days and perform a partial water change before re-treating or treating with a different medication.
  • Always treat when you have time to observe fish and take appropriate action in the unlikely event of a bad reaction.
  • If required, mix with Malachite prior to adding to the pond, following the instructions above.



Apply NT Labs Koi Care Formaldehyde at 10ml per 150 gallons (681 litres) of pond water. Can be repeated once every 7 days up to a maximum of 7 doses

  • 250ml bottle treats 3750 gallons / 17050 litres
  • 500ml bottle treats 7500 gallons / 34100 litres
  • 1 Ltr bottle treats 15000 gallons / 68200 litres
  • 2.5 Ltr bottle treats 37500 gallons / 170500 litres


Do not use with orfe, rudd, tench or sturgeon/sterlet.
Do not use if the water temperature is above 30°C.
Do not use in hot, humid, thundery conditions.
Do not mix medications, other than combining with Malachite.


Q: How do I mix Formaldehyde & Malachite Green?
 A: If you are going to use these 2 products together then simply follow the instructions for each individual product, there is no need to adjust the dosage or to pre-mix the 2 treatments, you can simply apply one product followed by the other at the dosage on the instructions. Alternatively, for ease of use we would recommend using our pre-mixed F-M-G.



Courier Delivery: Next Working Day Service (for in stock items)
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