Para muestreo de fondos, de similares aplicaciones que los Surbers. Se fija al fondo gracias a su forma cilíndrica, teniendo habitualmente dientes que facilitan su fijación. Dispone de una red lateral en la parte inferior, con un filtro en su extremo. También se sirve con un recipiente de captura por si se prefiere utilizar en lugar del filtro. Realiza una función similar a una manga de plancton específica para el fondo. Los dispositivos de 14,5 cm de diámetro miden 40 cm de altura y son de aluminio. Opcionales las mallas de 250, 500 o 1000 micras (mismo precio para todas las mallas). Proponemos dos composiciones que son las más habitualmente utilizadas.
INFORMACIÓN COMPLETA DEL FABRICANTE
The Hess sampler is used in similar circumstances to a Surber Sampler but is even more accurate. The base of the Hess sampler is pushed into the substrate to make a seal. Two strong handles allow for forcibly pushing and rotating the cylinder into the stream bed. For use on harder substrates, the Hess Sampler is also available with teeth for cutting into the substrate, effectively converting the sampler into a cylindrical corer or stovepipe sampler.
The upstream side is sealed with a large upstream filter of preferred size to prevent any invertebrates entering the sampler through drift or when the external substrate is disturbed. The downstream side has a net bag fitted with a closed, screw on filter. Similar to a plankton net in shape, this bag will collect any invertebrates within the sample area. An expression of the number of invertebrates in relation to surface area sampled can then be calculated.
We have found the sampler robust enough to use in a tidal estuary where the upstream filter is severely tested. The upstream filter is affixed with velcro so is easily removable and washed for reuse.
The Hess Sampler is available to buy in individual components, allowing you to fully customise the sampler to your needs. By specifying both the upstream and downstream filters it is also possible to selectively sample the water column.
The Hess Sampler includes the metal pipe, nylon collar and jubilee clip for affixing the downstream filter and net. You will also need;
* Upstream Filter (available in varying mesh sizes)
* Downstream Net and Filter (available in varying mesh sizes)
Specification
Hess Sampler:
* Available with or without teeth on bottom of sampler
* Tube diameter: 150mm
* Tube height: 400mm
* Material: aluminium alloy
Also includes:
* nylon collar which the upstream filter is affixed to
* jubilee clip for affixing the downstream net and filter
Upstream Filter (Sold Separately):
* 150 x 150mm
* Available in a variety of mesh sizes

Downstream Net and Filter (Sold Separately):
* Length: 400mm
* Available in a variety of mesh sizes
