Floating cover test results: odour, ammonia, drinking water, heat loss and evaporation

Results at a glance

Laboratory results show what the cover does under controlled conditions. Results on your site depend on the liquid, the basin and the coverage achieved.

Odour and ammonia: DLG APPROVED

DLG, the German Agricultural Society, tests agricultural equipment against independent criteria. Hexa-Cover® R114 holds the DLG APPROVED test mark for reduction of ammonia and odour emission.

What was tested: covered and uncovered tanks filled with the same pig slurry, at 12, 14 and 18°C and at three ventilation rates. Odour was measured to DIN EN 13725 by ECOMA GmbH, and ammonia by LugtTec A/S.

Result: odour was reduced by 81 to 96% in every individual measurement, 88.6% on average. The reduction was highest when the odour load was highest, at 18°C with no ventilation. Ammonia emission was reduced by 96 to 99% at 98% surface coverage.

Good to know: the measurements were made in the laboratory in 2004 and first published as DLG report 5451F. DLG reviewed and republished them in 2026 as report 7593. The product was not tested in practical use, and the test liquid was pig slurry, not sewage.

Ammonia reduction by tank size

Larger tanks reach higher coverage because a smaller share of the surface lies along the wall. Source: DLG test report 7593, table 5.

Drinking water: AS/NZS 4020:2018

AS/NZS 4020 is the Australian and New Zealand standard for products in contact with drinking water. The Australian Water Quality Centre, part of the South Australian Water Corporation, tested Hexa-Cover® R114 and reported compliance on 15 November 2019.

What was tested: water held in contact with the product was examined for taste, appearance, growth of aquatic micro-organisms, cytotoxic activity, metals and organic compounds.

Result: pass on every test. The report states that the results demonstrate compliance with AS/NZS 4020 at area to volume ratios up to 15,000 mm² per litre at 20°C.

Heat loss: Aalborg University

The Department of Civil Engineering at Aalborg University in Denmark measured how much heat escapes through a Hexa-Cover® R114 layer. Hot water in an insulated box was left to cool with an open surface, and again with the surface covered.

Result: the cover reduced heat flux by 74% compared with a free water surface in the same setup.

Heat loss: newer models, 2026

In February 2026 Terry Frank Consulting of Canada, working as technical consultant for Hexa-Cover A/S, repeated the Aalborg method on three newer models: ED, HD and API.

Result: heat flux was 87.2 to 87.7% lower than open water. The API model insulated best.

Heat retention matters for heated process tanks, digesters and sludge storage. At Holbæk wastewater utility in Denmark, covering a sludge storage tank raised the temperature of the following process from 17.2°C to 19.7°C during a winter with outdoor temperatures down to -15°C.

Evaporation: field trial in Western Australia

Water Corporation covered open dams with Hexa-Cover® in a trial with researchers from the University of Western Australia at Wellstead. The Government of Western Australia reported that the covers reduced evaporation by 73% and saved more than 1.6 million litres of drinking water during the trial.

The manufacturer states up to 95% reduction of evaporation from a covered water surface.

Evaporation: outdoor comparison in Denmark

Hexa-Cover A/S ran its own outdoor comparison of three reservoirs in Denmark, repeated in the summers of 2012 and 2013. This is the manufacturer’s test, not an independent one.

Measured in operation: algae and water quality

East Gippsland Water in Australia covered the raw water reservoir at its Omeo water treatment plant in June 2017 and compared water quality with the two years before installation.

These are a water utility’s own operating figures, not a laboratory test, and they show what the cover did on a working reservoir.

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