Hydra Quartz - Pond Blanket Weed Treatment

Our Price:  £18.50
List Price:  £21.00
Saving Of:  £2.50 (12%)
(Inc. 20% VAT)(£15.42 Exc. VAT)
Pack Size:

Combo: Quartz + Bio Aquatic Bacteria

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  (17 Reviews)
  • Highly effective biological blanket weed treatment
  • Rapid action starts working immediately - No waiting weeks for results
  • Best barley straw alternative, without the usual barley straw mess
  • Shelf life 3 years, 1 kilo treats up to 12,500 litres

Brand:  HYDRA

The term blanket weed is used to describe various strains of filamentous algae and is known to appear within a pond as fine wispy hair like strands on the side of ponds. In some cases, the wispy hair like strands grow into thick candy floss like masses, that float freely on the water surface, creating a widespread nuisance for most pond keepers.

Similar to green water causing algae, blanket weed also spreads quickly within sun exposed ponds with nutrient rich water, especially those containing fish. If left untreated the blanket weed may cause chocking towards plants and fish within the pond.

Pond keepers sometimes pull out the live blanket weed themselves, which results in the shedding of numerous spores within the water. These spores eventually grow, and blanket weed returns in a rather severe form, covering an even larger water surface.

What causes blanket weed growth within ponds?

There are three main factors that can cause blanket weed to form within ponds: excessive sunlight and nutrients, and a high pH level. These factors are also the possible reason for any reoccurring blanket weed problems.

When pond keepers overfeed their fish, it causes additional nutrients (nitrates and ammonia) to be released into the water, mixed with excessive fish excrement, it provides blanket weed with the nutrients it needs to develop.

Sunlight is a natural growth stimulant, also known as photosynthesis, for all plants, including aquatic plants such as blanket weed.

If your pond pH level is above 8.5, it becomes the best living environment for many forms of algae, including blanket weed, to grow.

Problems caused by blanket weed within ponds;

  • Blanket weed consumes large amounts of oxygen from the water and can create a harmful environment for fish and aquatic plants as they are forced to compete with the blanket weed for oxygen.
  • Fish can get tangled and caught up in the submerged blanket weed. If unable to escape, it can result in the fish suffocating and dying.
  • Not only does blanket weed make your pond look unappealing, it can also be sign that your chemical balance isn’t right within the pond, even if your water is clear.
  • Floating blanket weed blocks and deprives submerged pond oxygenating plants of sunlight. Without the sunlight, photosynthesis cannot occur, meaning the plant cannot grown and produce oxygen for the water, reducing the pond oxygen levels further.
  • When you have blanket weed within your pond, it ruins the aesthetics of your pond.

The solution

Hydra Quartz is a highly effective treatment to rid your pond of blanket weed as it starves the blanket weed by absorbing the nutrients on which the weed survives on. The blanket weed growth dies off normally within two to three days, after which, it can be safely removed without the risk of releasing spores into the water.

Features & Advantages

  • Hydra Quartz granules are easy to apply and can be broadcast or sprinkled directly over the pond blanket weed patch.
  • Works on the principle similar to traditional barley straw treatment but gives faster results. No need to deal with smelly, decomposed straw.
  • This enzyme and bacterial action help to prevent the re-infestation of blanket weed.
  • No need to switch off the UV lights.
  • Biological filters and pumps remain unaffected during treatment.
  • Natural and eco-friendly components of Hydra Quartz pose no danger to aquatic life including fish and water plants. Safe with pets, birds and visiting animals that may drink treated water.
  • No harmful effect on concrete surfaces or synthetic liners.
  • No effect on the pH level of the water.
  • It is the best garden pond blanket weed solution to cure blanket weed.




As with all water treatments, use at the coolest time of the day. DO NOT use on very hot days or thundery/stormy weather. We recommend using when your water is above 12˚C.

Only treat half the pond at one time. Use half the total dose required. 48 hours later, treat the other half of the pond with the remaining amount.

Directly broadcast/sprinkle Hydra Quartz over area of pond being treated, (as if you are sowing grass seed).


Switch your water pump and aeration on.

The blanket weed will turn grey or jellyfish-like transparency. Simply net any blanket weed or algae that floats to the top.


NOTE - After application, do not allow undiluted granules to remain in area where humans/animals are exposed. Non-target plants will suffer contact burn if undiluted granules are accidentally spilled on them. If they have granules on them simply rinse off with water.

Is it pet friendly?

Yes, Hydra Quartz treated water does not pose any danger to aquatic life and is safe for pets, birds, and other visiting animals that may drink the treated water.

Will it kill underwater plants and snails living in my water feature?

No, Hydra Quartz is natural and eco-friendly so does not pose any danger to aquatic life including fish and water plants.

What outside temperature can you start using Quartz?

The temperature of the water should be 12c or above.

Average Rating (17 Reviews):  
Write a Review and share your opinions!

The best blanket weed remover
26 March 2023  | 

Removing blanket weed.
I have been trying to kill blanketweed for years and have tried everything now I have discovered Hydra I don't have a problem.
Fantastic product.

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1 of 1 people found this review helpful.

Quartz Purchase
05 July 2022  | 

Received my order for blanket/string algae treatment, delivery was quick and on time, treated pond as instructed, this being in 2 doses over 48 hrs apart, noticed a difference in algae appearance within hrs
It's been just over a week now and blanket weed has died back to just over a cm long and still reducing,
No waste on bottom of pond as all being removed by filter
Very happy so far with product
Best regards

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2 of 2 people found this review helpful.

13 May 2022  | 

This product is absolutely brilliant. I donít usually leave reviews but Iím so grateful for the way this has cleared up my pond. It was so full of slimy pond weed - it just looked awful. I tried barley bales, barley liquid and manually pulling the weed out to no avail. This stuff cleared the pond in less than a week. It looks pretty repulsive while the treatment is getting to work but the results are amazing and the treatment is so easy to use. Iím going to ensure I always have some in stock and the moment I see the slightest bit of blanket weed I will sprinkle it with this. Very happy with the results!

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1 of 1 people found this review helpful.

Was skeptic, but its brilliant!
24 May 2021  | 

Hello guys
What can I say, over the years I have used products that claim to kill off blanket weed, so when I used your product it was used with some scepticism, well, that was short lived, it done exactly what it said on the tin (or should I say bucket), it made the pond look messy for about 24 hrs, after that, it was obvious that it was doing its job, brilliant, and only too happy to recommend, the fast delivery was appreciated.
John Burden

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4 of 4 people found this review helpful.

New Review
31 July 2020  | 

well wot can I say ordered yesterday 30th July ----arrived today 31st July ---------------that is good service in any bodies book .
So well done to your team

Many Thanks



1 of 1 people found this review helpful.

New Review
07 July 2020  | 

Hello Hydra Int,

I felt it would be nice to say a big thank you for the prompt delivery of this order. It must be very challenging to deal with orders during these trying times yet you somehow manage to give the same service as was experienced prior to the pandemic. Well done!

Kind regards



This review has not been appraised.

29 May 2020  | 

I have been using this product since 2016. It really is truly magical as all traces of blanket weed disappear almost instantly. I've just ordered it for a second time. The delivery serivice is also five star. The product arrived within 24 hours of my ordering it online. Thank you very much for such a brilliant service.

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2 of 2 people found this review helpful.

Hydra Quartz blanket weed treatment
15 June 2019  | 

This product does exactly as it states on the tin. I had an awful problem with blanket weed. I kept pulling great bundles of it from my pond, both from the bottom and around the edges. This product literally worked within the hour. Now a week on all traces of the weed have gone. Excellent product. My compliments to the chef.

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42 of 42 people found this review helpful.

Only treatment that seems to work!
16 May 2017  | 

I've been using this for years as it seems to be the only treatment that works and works fairly quickly. Usually needs two or three treatments but it clears the weed and it doesn't return until the following year. Pond has a lot of goldfish in (close on 200 probably) and in full sun and previously we have tried both natural and chemical treatments but this is by far the best.

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19 of 19 people found this review helpful.

Keech Hospice Pond
15 May 2017  | 

I buy Hydra Quartz to treat Blanket Weed in the Keech Hospice pond which has no filter system just a fountain. It gave good results last year so we are treating it again this year. At present the blanket weed is minimal.

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11 of 11 people found this review helpful.

Read all 17 customer reviews...

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