- A simple pressure washer can be used from on board a support vessel to clean infrastructure at the site.
- Disk washers can be deployed from the surface or used by divers within the cage.
Key Factors Positive
- An effective technique for removing all types of fouling.
Key Factors Negative
- It can be quite labour intensive.
- Is limited to use as part of the pre-sale processing for delicate species (e.g. scallop). For hardier species (e.g. mussels and oysters) it can be used periodically during the growing season.
- Not always possible to clean the entire cage without the use of divers, which involves another set of costs.
- Dislodged fouling is not necessarily killed and can resettle on local cages.
- Dislodged fouling passing through the cage can cause stress to stock animals.
- None of the CRAB partners use this strategy at present so no cost benefit analysis was possible.
- The use of disk washing slightly reduces the cleaning cost per sq. metre of netting per annum in combination with machine washing and as a combined strategy with machine washing and net drying (see Best Practice Guidelines for more details).
- A rotating jet of water was 100% effective (? 2000 psi for 2 seconds) in the removal of the kelp seaweed Undaria; a standard high pressure jet was less effective, removing only 60 to 90% of fouling depending on pressure and duration.
- High pressure water jets can be used to enhance mechanical cleaning and have successfully been used with oysters in this way.
- As stock pass through a rotating drum high pressure water jets help fouling and sediment removal as part of the processing system.
- Use of disk cleaners can increase the duration between net changes for cleaning purposes. They will have no effect on the timing of net changes to a different mesh size as stock gets larger though.