Hydra ST703 (Clear Filamentous Algae)

Hydra ST703 (Clear Filamentous Algae)
Pack Size: 1Kg upto 20,000LPack Size: 2X1Kg upto 40,000LPack Size: 3X1Kg upto 60,000LPack Size: 4X1Kg upto 80,000L
Pack Size: 5Kg upto 100,000LPack Size: 2X5Kg upto 200,000LPack Size: 3X5Kg upto 300,000LPack Size: 20Kg upto 400,000L
Pack Size: 2x20KgPack Size: 3x20KgPack Size: 4x20Kg
Our Price:  £14.95
List Price:  £20.60
Saving Of:  £5.65 (27%)
(Inc. 20% VAT)(£12.46 Exc. VAT)

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Brand:  HYDRA

  (5 Reviews)
  • Removes even the toughest of green filamentous algae and blanket weed
  • Absorbs the essential nutrients required for algae growth
  • Active ingredients ward off algae blanket weed long after the treatment
  • Shelf life 3 years, 1 kilo treats up to 20,000 litres

Features & Advantages

  • Hydra ST703 is effective upon more resilient forms of filamentous green algae.
  • Tough on algae but poses no danger to fish, birds, invertebrates, reptiles, animals, mammals, humans and water plants.
  • Works by feeding on the nutrients (phosphates and nitrates) that are important for the algae to grow.
  • Special product formula ensures residual effect which allows the continued action of Hydra ST703 long after the initial treatment.
  • No effect on biological filters
  • Available in easy to use powder form, that may be simply broadcast upon the affected surface.

How To Use

Usage Rate

  • 1 kg of Hydra ST703 treats 20,000 litres of water
  • 2x1 kg of Hydra ST703 treats 40,000 litres of water
  • 5 kg of Hydra ST703 treats 100,000 litres of water
  • 20 kg of Hydra ST703 treats 400,000 litres of water

Full instructions on the label.

Hydra ST703 quickly eradicates the most stubborn algae strains by starving them. The results should be visible within 2 to 3 days.

  • Make a mixture of Hydra ST703 using pond water in water can. Pour the mixture evenly across the pond surface. The water may turn milky upon contact with the product. This is normal and the water clears up in a few days.
  • You may also sprinkle the powder directly upon the algae to treat the highly infested area.
  • Repeat the treatment after 1 week at the same usage rate if some algae growth still remains in water.
  • For the product to be effective it is necessary that the water temperature is more than 12°C.


The Problem

Algae infestations are common in the water with excessive nutrients, including nitrates and phosphates. Other conditions that support algae to thrive are abundant sunlight and warm weather. You would be able to clear filamentous algae of most types with popular algae treatment product available on the shelf, but some strains of algae are particularly difficult to get rid of. These stubborn forms of algae do not respond to common treatment products or procedures and retain their shape and colour even after the product application.  Some of the most difficult algae strains to treat are Cladophoraglomerata, Enteromorpha Spirogyra, genus Charamacrophytic algae, Rhizoclonium and some varieties of blanket weed.

The Solution

Hydra ST703 is an outcome of the dedicated research efforts at ISO certified Hydra International Ltd. The product composition of Hydra ST703 includes a unique minerals and enzymes blend that rapidly starves off even the toughest algae. Hydra ST703 comes with an added advantage is its residual effect in the water which means that the product actively keeps off algae long after the initial application. Unlike most other products Hydra ST703 is effective even during cooler months of the year.

Average Rating (5 Reviews):  
Write a Review and share your opinions!

A product that really works
Saturday, 22 June 2019  | 

An excellent product Have tried others that just do not work This product (my 2nd) purchase really does and seems to be very long lasting


24 of 24 people found this review helpful.

Seems to work very well
Wednesday, 17 May 2017  | 

I've been using this product about once every 3 months since last year, and the algae is certainly very much more under control. So I recommend this product.


9 of 9 people found this review helpful.

Hydra ST703 (Clear Filamentous Algae)
Tuesday, 16 May 2017  | 

Cleared a fierce attack of algae growing from the bottom in 1 sprinkling over the surface.
Left a couple of white stains on the bottom where heavy doses had sunk to. These don't seem to want to go.
Water is extremely clear now.


5 of 5 people found this review helpful.

Hydra ST703
Monday, 15 May 2017  | 

I have tried different products from different companies over the years to reduce the blanket weed in my pond. A few years ago, I tried Hydra- Aqua Quartz, which I found very good at controlling the blanket weed, but last year I switched to ST703 and have been very happy with the product. I can see clearly down to the bottom of the pond and there is no blanket weed trying to grow on the side of the pond liner.


5 of 5 people found this review helpful.

great customer service
Tuesday, 9 May 2017  | 

I haven't used this yet as there was a problem with delivery, but got it sorted with thanks to the customer service team. I'm delighted with the outcome and looking forward to blanket weed free pond.


1 of 1 people found this review helpful.


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