Adsorba^® Beads

Advantage:
Due to the inert material -glass beads are made from pure silica- absolutely no components are beeing supsendet to the water. The nature of swimming - pool water wil be in no way affected.

Construction:
The dumping hight of the filter layer corresponds to the grain-size, resulting in a constant filtration-surface. Therefore, by combination of those two parameters (hight & grainsize), it is no problem to take lower installationplaces of filters into account.

There are different grades available. Advantage of the glass spheres: the glass bead filter material has got no other components, neither of organic nor inorganic nature. A dispense of any substance to the water to be filtered will definitely not take place.

A further advantage of this filter material is, that during the loading of the filter-material with flocculants, because of the capillaries -form due to the spherical shape of the glass beads -, a much sharper filtration (turbidity value <0.02 FNU) will be achieved, as with conventional filter material such as silica sand with granular structure.

The density of the material with 2.5 kg / L is nearly equivalent to quartz sand. However, the permeability of spherical filter material is about five times higher than with granular material with the same particle sizes like quartz sand. Thus, on the other hand, the specific resistance of spherical filter material is nearly five times lower than with granular materials of the same size. The Carman-Kozeny equation computes for grain sizes from 0.75 to 1 mm for glass beads:

1. Permeability: 1.5 E-08 m²

2. spec. Resistance: 79 689 m / kg

Permeabilität [ m²] Spezifischer Widerstand [m/kg]
Filtersand (0,4-0,9 mm) 3,18E-09 312311
Glas beads ( 0,25-0,5 mm) 3,17E-09 396536
Glas beads ( 0,4-0,6 mm) 5,11E-09 246136
Glas beads ( 0,5-0,75 mm) 7,79E-09 161421
Glas beads ( 0,75-1 mm) 1,57E-08 79689
Glas beads ( 1-1,3 mm) 2,72E-08 46149

This offers two options:
The grain size of the spherical-glass beads can be reduced to 0.25 - 0.5 mm. The above mentioned equation computes a permeability of 3.17 E-9 which is approximately the same permeability of filterquartz with the bigger grain-size of 0,4-0,9 mm. The spec. resistance of 396 536 m / kg as well corresponds to that of filter-quartz with bigger grain sizes. So with the same filtration performance, backwash water significantly can be saved, as the backwash speed is much lower with fine material. If however the water balance -the DIN 19643 requires a minimum of 30 L per bather- is not met, there is another possibility: Glass beads of the same grain sizes as Quartz are beeing used, thus spec. resistance is lower. This will reduce the pressure loss, pump power can be saved. Furthermore running life of the filter, water and energy can be saved. The backwashing of filter material basically is performed by reversing the flow direction from the bottom to the top of a filter. Due to the plane surface of the beads, deposited materials (aluminum hydroxide, Aluminium-phosphat, turbidity, flakes ...) will much more easier be removed from the filter body into the sewerage system or the receiving waters. Since the filter material possesses no obstacles (undersized- & oversized aprticels, non uniform, bumpy ore jagged shape) backwashing with a maximum of 2.5 to 3 m3 / m2 filter area can easily be achieved.

Note: according to DIN, systems need up to 11 m3 / m2 backwash-water.

The backwash speed is about the same as with filter sand about 60-80 m/h, depending on temperature and grain size of the filter material, and may be at a finer grain size reduced even more significantly (less than 30 m/h ). These advantages allow in both, the public and private pools, different backwash-frequenzes. Periods of ones a week up to once all 14 days is possible. Besides the savings in water, wastewater, energy and chemicals, this process contributes significantly to the conservation of resources.