water treatment Water feature designers and contractors

:: plumbing
:: nozzle design
:: specialist metalwork
:: spillways
:: pneumatic control systems
:: hydraulic control systems
:: sound and water shows
:: fire and water shows
:: aquaria and zoo exhibits
:: artificial rock work
:: lights
:: waterproof membranes
:: decorative finishes
:: water treatment
:: fish and aquatic plants

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Grand Building

Location: Trafalgar Square, London

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Grand Buildings is a speculative office block standing on the corner of Northumberland Avenue and Trafalgar square. At the centre of the building there is an atrium and at the foot of the atrium there is a circular pool, surrounded by a range of tropical plants. The pool was originally intended to support water lilies and the circulation system was designed and installed by the main M&E subcontractor. However after a few weeks the water turned green and the pool was drained down. Six months later Hydrotechnology were called in to rectify the problem.

The decision was made to install a large biological filter, a sand filter and a UV steriliser. There was already a fall back tank in the sub basement but the pipework was small bore copper so the rate of turnover was very small. The solution was to use the 4 drain at the centre of the pool as a gravity return to the basement and to use both the existing supply and return pipe work to carry water back to the feature. A 6 inch stainless steel pipe work had to be threaded through the existing service routes down to the sub-basement.

A steel frame was constructed adjacent to the existing fall back tank and a prefabricated fibreglass tank was placed on top of it in such a way that part of the water flows through the biological filter on its way to the fall back tank whilst the majority takes a more direct route. Water is drawn from the fall back tank and re-circulated through a 3 inch sand filter to remove any suspended solids. Water is then drawn out of the tank by a large pump. On its way part of the flow passes through an industrial UV steriliser. The consequences of this system is that the pool water is cleaner than the drinking water supply in the building.

Hydrotechnology advised the client to forget about using water lilies but instead elected to stock the pool with fish. They are very healthy and thrive in the clean water with its high oxygen levels which results from the water tumbling down the pipework on its way back to the basement after it leaves the pool. Whilst the pool is being cleaned the fish are removed and placed in their own special holding tank in the basement.

Next case study: The Great Northern Experience 

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