NT Labs Koi Care - Mediclay

Item: 157

MPN: 00358

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1.5kg NT Labs Koi Care - Mediclay
Was £19.99 Now £17.99 (Available)
5kg NT Labs Koi Care - Mediclay
Was £54.99 Now £46.99 (In stock)
20kg NT Labs Koi Care - Mediclay
Was £149.99 Now £119.99 (In stock)

Product Description


NT Labs Koi Care - Mediclay


When to use?
Use as a weekly additive to re-mineralise pond water to control the build up of organic waste, bacteria and pollutants which cause bacterial infections and ill health.

Mediclay stimulates the biological system in favour of beneficial bacteria helping to reduce algae. Mediclay will also “polish” the water resulting in amazing clarity to observe your fish.

How to use:

  • Mix the required dose in a clean bucket/watering can of pond water then pour over the surface of the pond or at a filter outlet to ensure an even spread.
  • For clarifying the water, Mediclay is best applied via the pump or venturi so that it is rapidly mixed with the water returning to the pond.
  • Use in conjunction with other NT Labs water treatments but leave 48 hours after using an NT Labs Medication before applying Mediclay.
  • Mediclay can be used at any time of year (water temperature) and will not alter the water pH.



1.5 kg treats 272,760 litres (60,000 gallons)
20 kg treats 3,368,000 litres (800,000 gallons)


Do not:
Use within 48 hours of applying a medication.


Q: What is Mediclay?
 A: Mediclay is a high-purity montmorillonite clay containing a variety of minerals and trace elements which are beneficial to fish health and water quality and clarity. Montmorillonite clays are produced by the weathering of volcanic ash, and are hence high in minerals.
Q: What does Mediclay do? A: Weekly additions of Mediclay will re-mineralise your pond water to control the build-up of organic waste. Additionally, Mediclay will clarify the water and encourage the biological filter to perform at its best, reducing the potential for harmful ammonia and nitrite spikes. It is also widely accepted that the use of montmorillonite clays, such as Mediclay, enhance the skin quality and brightens the colours of fish.
Q: How does Mediclay work? A: This is a more complicated question than it may appear. It largely boils down to the negative charge of the clay particles and their size/structure. Refer to the "How does Mediclay Work" Tab.
Q: How does Mediclay remove toxic substances from the water? A: As Mediclay particles have a negative chemical (ionic) charge, positively charged ions will be attracted to and will bond with particles of Mediclay. This doesn’t technically remove these toxic substances, such as heavy metals, ammonia and pesticides, but instead locks them away preventing them from harming fish. During water changes and filter cleans, the Mediclay will slowly be removed and thus these toxic substances are removed as well.
Q: How often can I use Mediclay? A: You can use Mediclay as a weekly additive to your pond or sporadically throughout the year when you think your pond needs a bit of a pick-me-up. The use of Mediclay will never harm your fish, provided you follow the dosage shown on the label.
Q: Can I use Mediclay alongside a medicinal treatment? A: Yes, but we recommend you wait two days after applying Mediclay before using a medicinal treatment. As good as Mediclay is, it doesn’t distinguish between the ‘extra’ particles in the water that we don’t want there and the medications we add on purpose!
Q: Will adding Mediclay alter the pH of my pond? A: Continued use over an extended time period may raise the pH. However, this depends on the current pH level of the pond. If you need a product to adjust the pH, take a look at our KH - Buffer Up instead.


How Does NT Labs Koi Care Mediclay Work

Clay has been used for centuries in water bodies due to its “magical” properties. These properties aren’t quite magical, and this article breaks down some of the tougher science to examine how clays, such as Mediclay, do what they do and why they are so effective.

Absorption of harmful ions:

Clay ions are negatively charged and arranged in sheets which sit on top of one another. This means they are able to attract positively charged ions, such as ammonium and heavy metal ions. These molecules then form ionic bonds, locking the harmful ions away so they cannot cause damage to fish or the filter bacteria. Compared to other clay particles, the gaps between the sheets of atoms in montmorillonite clay are much bigger, which increases the surface area and allows more harmful ions to be absorbed per particle of clay.

Clarifying water:

The particle size of Mediclay is very small. However, compared to other particles in the water which make the water appear cloudy, the size of clay is very large. As a result, these tiny, particles are drawn to the larger clay molecules and are dragged down to the bottom of the pond as the clay slowly sinks, clearing the water. In this way, Mediclay acts a flocculant (it causes particles to clump together). Additionally, as Mediclay is such a fine powder, the particles are in suspension for a longer period of time, allowing them to gather more particles before they reach the bottom of the pond.

Beneficial to fish health:

After the Mediclay particles have sunk to the bottom of the pond, many fish will nibble and ingest clay particles. As these particles work their way through the digestive tract, they will bind to positively charged impurities and encapsulate them. These will then be discarded by the fish within their waste, and can then be picked up by the filter and removed. Similarly, there is anecdotal evidence which suggests that any free-swimming or suspended pathogenic bacteria or parasites are encapsulated by clay particles in a similar way and effectively neutralised. This prevents these pathogens from attacking fish, helping to maintain the health of the fish in your pond. Additionally, Mediclay contains a variety of essential trace elements and minerals which fish can only gather from their diet, which help to keep your fish healthy.

Aids biological filtration:

Mediclay contains carbonates and a variety of trace elements which are essential for plants and bacteria. Carbonates are used by the nitrifying filter bacteria to detoxify ammonia and turn it to nitrite and subsequently nitrate. By adding additional carbonates to the water, the filter bacteria can more efficiently and quickly break down ammonia and nitrite produced by fish waste and change it into non-toxic nitrate which will not harm fish.

Controls build-up of waste:

Mediclay contains calcium, a mineral vital for the action of enzymes to take place. In fact, calcium acts as a catalyst for enzyme action, so the addition of Mediclay increases enzyme activity, resulting in food being digested more thoroughly and faster by your fish. This reduces waste and maximises nutrient uptake by your fish, and in turn, stimulates the appetites of fish to gain more of these nutrients.

Enhances skin quality and brightens colours:

It is most likely that this boost is caused by the uptake of more nutrients from the fish’s diet as well as the addition of essential trace elements and minerals to the fish’s diet. Why not try it for yourself and see if your fish’s colours improve? Do let us know!

The ancestors of koi are naturally found in clay-rich, muddy ponds, so it’s no wonder they appreciate the addition of clay so much. It may be the difference between the koi merely surviving in your pond and thriving in it, so why not add some clay to your pond?



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