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Installation & Maintenance

We build and maintain beautiful aquariums.

Free Shipping Over £50

Spend over £50 on your order and qualify for free shipping.

Flexible Payment Options

We offer flexible monthly finance options.

Price Match

Found item from our catalog cheaper? We'll price match it!

Reward Points

As a thank you, we run the Charterhouse Points scheme.

Seachem Reef & Marine Water Additives

Our Black Friday Sale has arrived!  

Save 10% on all orders!

Seachem Reef Fusion 1 & 2 500ml Pack

£20.88 £18.79
  In Stock
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Seachem Reef Fusion 1 & 2 2L Pack

£52.00 £46.80
  In Stock
 Add To Cart

Seachem Reef Fusion 1 500ml

£10.59 £9.53
  In Stock
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Seachem Reef Buffer - 500G

£17.79 £16.01
  In Stock
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Seachem Reef Fusion 2 500ml

£10.44 £9.40
  In Stock
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Seachem Reef Buffer - 250G

£9.95 £8.96
  In Stock
 Add To Cart

Seachem Reef Fusion 1 2L

£24.95 £22.46
  In Stock
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Seachem Marine Buffer - 250G

£8.99 £8.09
  In Stock
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Seachem Reef Fusion 2 2L

£24.95 £22.46
  In Stock
 Add To Cart

Seachem Marine Buffer - 500G

£13.99 £12.59
  In Stock
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Seachem Reef Pack Fundamentals

£20.39 £18.35
  In Stock
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Seachem Reef Pack Enhancer

£11.95 £10.75
  In Stock
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Seachem Reef Advantage Magnesium - 600g

£12.06 £10.85
  In Stock
 Add To Cart

Seachem Reef Advantage Strontium - 600g

£13.17 £11.85
  In Stock
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Seachem Reef Builder - 600g

£12.99 £11.69
  In Stock
 Add To Cart

Seachem Liquid Marine Buffer - 500ml

£13.99 £12.59
  In Stock
 Add To Cart

Seachem Reef Phytoplankton 250ml

£8.19 £7.37
  3-4 days
 Add To Cart

Seachem Reef Calcium - 500ml

£13.49 £12.14
  In Stock
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Seachem Reef Carbonate - 500ml

£9.77 £8.79
  In Stock
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Seachem Reef Phytoplankton 500ml

£14.69 £13.22
  In Stock
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Seachem Reef Complete - 250ml

£11.09 £9.98
  In Stock
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Seachem Reef Complete - 500ml

£15.19 £13.67
  In Stock
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Seachem Reef Dip - 500ml

£24.95 £22.46
  In Stock
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Seachem Reef Iodide - 500ml

£16.91 £15.22
  In Stock
 Add To Cart

Seachem Reef Kalkwasser - 500g

£15.99 £14.39
  In Stock
 Add To Cart

Seachem Reef Plus - 250ml

£9.99 £8.99
  In Stock
 Add To Cart

Seachem Reef Plus - 500ml

£16.99 £15.29
  In Stock
 Add To Cart

Seachem Reef Strontium - 500ml

£15.49 £13.94
  In Stock
 Add To Cart

Seachem Reef Trace - 500ml

£13.29 £11.96
  In Stock
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Seachem Marine Trace - 500ml

£12.99 £11.69
  In Stock
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Seachem Reef Advantage Calcium - 500g

£12.95 £11.66
  3-4 days
 Add To Cart

Seachem Reef Fusion 1 4l

£46.96 £42.26
  In Stock
 Add To Cart

Seachem Reef Buffer (4KG)

£65.99 £59.39
  In Stock
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Seachem Reef Buffer 50g

£3.95 £3.56
  In Stock
 Add To Cart

Seachem Reef Buffer 1KG

£23.09 £20.78
  In Stock
 Add To Cart

Seachem Reef Fusion 2 4l

£48.95 £44.05
  In Stock
 Add To Cart

Seachem Reef Advantage Calcium (4KG)

£82.99 £74.69
  Out Of Stock
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Seachem Reef Iodide 250ml

£9.77 £8.79
  In Stock
 Add To Cart

Seachem Reef Advantage Strontium 70g

£3.70 £3.33
  In Stock
 Add To Cart

Seachem Reef Advantage Strontium 300g

£7.98 £7.18
  In Stock
 Add To Cart

Seachem Reef Strontium - 250ml

£7.95 £7.16
  In Stock
 Add To Cart

Our Bestsellers

Seachem Reef Advantage Magnesium - 600g

Seachem Reef Advantage Magnesium - 600g

£12.06
Reef Advantage Magnesium is a concentrated (80,000 ppm) optimized blend of magnesium, chloride, and sulfate salts designed to restore depleted levels of magnesium with minimal impact to the ionic ratios found in natural sea water.
  In Stock
 Add To Cart
Seachem Reef Buffer - 500G

Seachem Reef Buffer - 500G

£17.79
Reef Buffer™ is intended primarily for use in a reef system where the maintenance of a pH of 8.3 is often difficult.
  In Stock
 Add To Cart
Seachem Reef Advantage Calcium - 500g

Seachem Reef Advantage Calcium - 500g

£12.95
Reef Advantage Calcium is a non-caustic (pH 8.3–8.6) optimized blend of ionic calcium designed to restore and maintain calcium to levels found in natural seawater.
  Dispatch in 3-4 days
 Add To Cart
Seachem Reef Phytoplankton 500ml

Seachem Reef Phytoplankton 500ml

£14.69
Reef Phytoplankton™ is a concentrated blend of green and brown marine phytoplankton designed to provide the essential fatty acids, proteins, vitamins, amino acids, with biological carotenoids for invertebrate diet.
  In Stock
 Add To Cart
Seachem Reef Fusion 1 & 2 2L Pack

Seachem Reef Fusion 1 & 2 2L Pack

£52.00
Reef Fusion 1™ and Reef Fusion 2™ are the foundation of a system formulated to provide the essentials for the reef aquarium. Reef Fusion 1™ provides calcium, while Reef Fusion 2™ provides alkalinity. When used together, the Reef Fusion™ system will maintain calcium and alkalinity levels.
  In Stock
 Add To Cart
Seachem Reef Builder - 600g

Seachem Reef Builder - 600g

£12.99
Reef Builder raises carbonate alkalinity without immediately impacting on pH. With long term use there will be a tendency to stabilize at pH 8.3. Carbonates and calcium are essential to all coral growth.
  In Stock
 Add To Cart
Seachem Reef Kalkwasser - 500g

Seachem Reef Kalkwasser - 500g

£15.99
Reef Kalkwasser is a pure calcium hydroxide with unsurpassed purity and solubility characteristics. Calcium hydroxide is used to prepare limewater (kalkwasser) solutions that will maintain calcium concentrations at natural seawater levels.
  In Stock
 Add To Cart
Seachem Reef Fusion 1 & 2 500ml Pack

Seachem Reef Fusion 1 & 2 500ml Pack

£20.88
Reef Fusion 1™ and Reef Fusion 2™ are the foundation of a system formulated to provide the essentials for the reef aquarium. Reef Fusion 1™ provides calcium, while Reef Fusion 2™ provides alkalinity. When used together, the Reef Fusion™ system will maintain calcium and alkalinity levels.
  In Stock
 Add To Cart


Seachem products have been and continue to be based on sound science. They now cover the full spectrum of aquarium requirements in freshwater, seawater, reefs, and ponds. They include buffers, conditioners, filtration media, medications, and test kits. Most of Seachem's products are totally unique and specific to Seachem.

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Why our delivery is awesome!

Just a few reasons why Charterhouse are the industry leaders

1 Hour Delivery Slot

We provide a 1 hour delivery slot for all Premium Next Day delivery services. No more waiting in all day.

SMS And Email Notification

Your delivery slot will be text and emailed to you. You can then submit a different day or request the parcel is left with a neighbour.

Weekend Deliveries

We now offer deliveries on both days of the weekend. These services can be selected at checkout.

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Free Shipping Over £50

Spend over £50 on your order and qualify for free shipping. Next day and timed services available.

Find out more

Flexible Payment Options

We offer flexible monthly finance options. Credit is subject to application and status.

Find out more

Reward Points

As a thank you, we run the Charterhouse Points scheme. Earn points on every order.

Find out more