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Deputy pleased with new algae trial

Deputy pleased with new algae trial

Tuesday 07 June 2022

Deputy pleased with new algae trial

Tuesday 07 June 2022

A trial is underway of a new approach to removing algae from marine slipways.

A macroalgae cleanser is being used at the Bathing Pools at Havelet, pictured top, as part of the States' efforts to find an alternative to sodium hypochlorite.

The purpose of the trial was set out by the President of the Committee for the Environment & Infrastructure in reply to Rule 14 questions submitted by Deputy Gavin St Pier.

"In line with the Committee’s aim to reduce chemical inputs into the environment, potential alternatives have been trialled," said Deputy Lindsay de Sausmarez. 

"A macroalgae cleanser has been trialled since 2018 in different circumstances, with differing levels of success. We have learned and continue to learn about how best to use the product and in what circumstances. It is currently being trialled at the Bathing Pools.

"We are not aware of any direct, scientific comparisons between the environmental impacts of the macroalgae cleaner and sodium hypochlorite but they are claimed to be less in the former."


Pictured: Algae is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It can build up in marine environments, such as slipways and piers, and needs to be cleared for safety. 

The Rule 14 question asked the Committee "what work has and is being undertaken to identify a less ecologically damaging alternative to the use of sodium hypochlorite for the removal of algae from marine slipways".

After receiving the Committee's reply, Deputy St Pier told Express: "The issue of the use of sodium hypochlorite and its environmental risk was drawn to my attention by a concerned member of the public. I was keen to understand whether Environment & Infrastructure was aware of the issues and looking at alternatives.

"I am pleased that it has been keeping the matter under active review. The challenge is to find an environmentally less toxic substance that is at least as effective. Having informally engaged with the Committee, I lodged the question formally to have the response on record and in the public domain."

Deputy Gavin St Pier

Pictured: Deputy Gavin St Pier submitted Rule 14 questions after being approached about the issue by a member of the public.

Sodium hypochlorite has been in use for many years as the main substance to remove macroalgae from the 52 piers, jetties and slipways looked after by the Committee through its Agriculture, Countryside and Land Management (ACLMS) division.

The Committee said it is used in a 50/50 dilution which breaks down into harmless products from around one hour after use, depending on conditions.

Hot foam has also been trialled as another more environmentally-friendly alternative to sodium hypochlorite but has been ineffective at removing all algae.

Deputy Lindsay De Sausmarez

Pictured: In reply to Rule 14 questions, Deputy Lindsay de Sausmarez explained the thinking of her Committee for the Environment & Infrastructure on cleaning algae from marine slipways. 

"We will continue to explore alternatives to the use of sodium hypochlorite," said Deputy de Sausmarez. 

"It is currently the main cost effective option that meets the challenges of making safe 52 piers and jetties, often in inaccessible areas, within the limited time that our tides allow.

"We are also open to trying a mix of approaches, should they balance those challenges whilst reducing further any ecological impacts."

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