Requirement

Heathland Group was contacted by Center Parcs with a requirement for an aeration system at Longleat Forest that would be capable of effectively supplying high volumes of oxygen to a 23,000m2 water sports lake plagued by algae.

Being a recreational lake, it was paramount that the water aeration system would be safe for visitors whilst carrying out the heavy-duty of maintaining healthy dissolved oxygen (DO) levels in a large body of water.

Issue with the lake 

The most prevalent issue was single-cell algae causing smells during summer periods, and pea-green water.

This had resulted in the closure of the lake and, in turn, loss in profits from the water sports activities the park offered. The cost of the lake closure totalled more than the cost of a supplied and installed aeration system.

Single-cell algae can cause harm to a lake. Not only can they be unsightly and smelly but they can also disrupt the delicate balance of the lake and even cause harm to human life, especially during algal blooms. HABs (Harmful Algal Blooms) are capable of contaminating water, making it unfit to swim in.

Why the OxiAir HD® diffused aerator was selected

OxiAir HD® excels at delivering sustainable DO levels to all areas of the lake and ensures a constant turnover of the water column, preventing thermal stratification in addition to removing the unwanted algae. The former reduces the effects of stagnation, stratification and aids strongly in the efficient release of sediment gases which would otherwise be trapped in the lower layers of the lake during the warmer months of the year.

Main challenges

The size of the lake was the biggest challenge. Planning is a key part of Heathland Group's water aeration installation service. Prior to arriving at the site the company worked on a layout diagram to ensure all areas of the lake had access to oxygenated water. In order for this to work efficiently Heathland Group needed to calculate the depths of shallow and deep water and ensure that the correct balanced air flow levels were delivered to the disc membrane diffusers that were strategically lowered from its boat into the lake, sinking until reaching the lake bed where they will stay.

To calculate where the aerators should sit at the bottom of the lake the company had to take into consideration the shape and size of the lake, as well as consider natural air movement, fish stock and general usage requirements of visitors.

The well-being and enjoyment of the park customers was also a priority. 

  • An aeration system was required that wouldn't disturb the park visitors during their activities.

  • Health and safety standards had to be upheld; the aerator needed to be subsurface so that it wouldn't interact with lake users or get tangled with water sports equipment.

  • The hose used to supply the disc membrane aerators with oxygen from the pump had to be heavy enough to stay at the bottom of the lake bed.

  • The pump motor had to be as quiet as possible so as to not disturb visitors.

Power supply

27 diffusers with 2 OxiAir HD® units were installed. 15 of the 27 diffusers were connected to the larger unit with a single-phase 230v / 50Hz power supply.

Result

Installation took 2 days, 27 disc membrane diffusers, approx. 3000m of HeathSink® hose, and 2 OxiAir HD® units.

Center Parcs Longleat Forest site management is pleased with the efficiency of the whole operation. The diffusers and the OxiAir HD® deliver oxygen to the lake, clearing the algae and enabling the lake to re-open for the enjoyment of visitors.