| C L A I M S 1. An additional filter (16) for an existing cartridge- -like pool filter (13) of a pool (1) , said pool (1) being filled with water from a source containing metal compounds via a piping system, and comprising a circulation loop (2) that contains a pump (3) having a filter housing (10) for the filter cartridge (13) , for separating visible organic matter from the pool water circulating therethrough, wherein the pool water contains metal compounds originating from said source and piping system and causing the pool water, after a certain period of use, to become discoloured by coloured particles formed in the pool water, characterized in - that the additional filter (16) comprises a plurality of water-permeable filter layers of a thin fabric material contacting each other, and is dimensioned and designed to be fitted around the existing filter cartridge (13) in order to completely enclose the filter cartridge (13) with a main portion, and - that each filter layer has, on the one hand, larger apertures, wherein some of the larger apertures of the filter layers are completely or partially aligned with each other to form throughflowing passages for the circulating water, and, on the other hand, smaller apertures of varying sizes, that prevent passage of the water-discolouring particles which are distributed within a specific size range, the upper value of which constitutes a limit value for the transition between said larger apertures and said smaller apertures. 2. The additional filter according to claim 1, characterized in that at least some of said larger apertures are of sizes forming said throughflowing passages, in order to allow a high water permeability so that the flow rate in said circulation loop (2) is minimally influenced. 3. The additional filter according to claim 1 or 2 , characterized in that said smaller apertures comprise small apertures of varying sizes preventing passage of water-discolouring particles larger than about 30 microns, said particles thereby being trapped and retained by the filter layers. 4. The additional filter according to any one of claims 1-3, characterized in that said limit value is about 600 microns. 5. The additional filter according to any one of claims 1-4, characterized in that it is designed as a sleeve having end portions (19, 20) defining opposite end openings (17, 18), wherein the filter cartridge (13) is arranged to be inserted through one of these end openings (17, 18) to form a filter assembly (23) for positioning in a filter chamber (11) in the filter housing (10) . 6. A method of removing water-discolouring particles from water in a pool (1) , which is filled with water from a source, that contains metal compounds, via a piping system, said pool comprising a circulation loop (2) , that contains a pump (3) having a filter housing (10) for a filter cartridge (13) for separating visible organic matter from the pool water circulating therethrough, wherein the pool water contains metal compounds originating from said source and piping system and causing the pool water, after a certain period of use, to become discoloured by said coloured particles formed in the pool water, characterized in - that the circulation through the circulation loop (2) is stopped and the existing filter cartridge (13) is removed from the filter housing (10) , - that an additional filter (16) , that comprises a plurality of water-permeable filter layers of a thin fabric material contacting each other, is fitted around the removed filter cartridge (13) in order to completely enclose the filter cartridge (13) with a main portion, said filter layers each having, on the one hand, larger apertures, wherein some of the larger apertures of the filter layers are completely or partially aligned with each other to form throughflowing passages for the circulating water and, on the other hand, smaller apertures of varying sizes, that prevent passage of the water-discolouring particles, which are distributed within a specific size range, the upper value of which constitutes a limit value for the transition between said larger apertures and said smaller apertures, - that the filter assembly (23) of the existing filter cartridge (13) and the additional filter (16) is positioned in the filter housing (10) , - that the circulation through the circulation loop is then started again and allowed to continue for a predetermined period of time, - that the circulation is then stopped and said filter assembly is removed from the filter housing, - that the additional filter (16) , that is dirty with water-discolouring particles, is removed from the filter cartridge (13) and is replaced with a new, clean additional filter (16) , and - that the procedure as above is repeated as required, until an acceptable clarity has been obtained. 7. The method according to claim 6, characterized in that said predetermined period of time is within 24±6 hours . 8. The method according to claim 6 or 7, characterized in that the procedure is repeated 3-6 times, preferably 4-5 times. 9. The method according to any one of claims 6-8, characterized in that at least some of said larger apertures are of sizes forming said throughflowing passages, in order to allow a high water permeability so that the flow rate in said circulation loop (2) is minimally influenced . 10. The method according to any one of claims 6-9, characterized in that said smaller apertures comprise small apertures of varying sizes, that prevent passage of water-discolouring particles larger than about 30 microns, said particles thereby being trapped and retained by the filter layers. 11. The method according to any one of claims 6-10, characterized in that said limit value is about 600 microns. 12. The method according to any one of claims 6-11, characterized in that the additional filter (16) is designed as a sleeve having end portions (19, 20) , that define opposite end openings (17, 18), wherein the filter cartridge (13) is adapted to be inserted through one of these end openings (17, 18) to form a filter assembly (23) for positioning in a filter chamber (11) in the filter housing (10) . |
The present invention relates to an additional filter for an existing cartridge- like pool filter of a pool, said pool being filled with water from a source containing metal compounds via a piping system, and comprising a circulation loop that contains a pump having a filter housing for the filter cartridge, for separating visible organic matter from the pool water circulating
therethrough, wherein the pool water contains metal compounds originating from said source and piping system and causing the pool water, after a certain period of use, to become discoloured by coloured particles formed in the pool water.
The invention also relates to a method of removing water-discolouring particles from water in a pool, which is filled with water from a source, that contains metal compounds, via a piping system, said pool comprising a circulation loop, that contains a pump having a filter housing for a filter cartridge for separating visible organic matter from the pool water circulating
therethrough, wherein the pool water contains metal compounds originating from said source and piping system and causing the pool water, after a certain period of use, to become discoloured by said coloured particles formed in the pool water. Pools, such as outdoor pools, indoor pools, whirlpools and the like, which are filled with water from a well or lake via a piping system in the ground, will contain different metal compounds such as iron, copper and manganese compounds, and others, and usually also calcium compounds. For hygienic and health reasons, bactericidal agents, such as chlorine or a chlorine-releasing chlorine compound, are added to the water in the pool to kill bacteria therein. After a certain time, depending on the composition of the well water, the pool water becomes discoloured so that it turns blue, green, brown, reddish- -brown, black or blackish-brown. As a measure to remove this discolouration, the pool manufacturers propose or recommend that the water in the pool is subjected to shock- treatment with chlorine. Such a chlorine treatment, however, does not give the desired result and is
furthermore detrimental to the human body as well as nature. Another possibility is to provide expensive special filters for removing the discolouring matter, but because of, among other things, the price of
SEK 10000-30000 per special filter, this is not an acceptable solution. Since municipal water has a
different composition than well water, that does not cause any discolourations , it has been proposed that the pool is completely or partially filled with municipal water, for example by getting the rescue corps to handle the filling by means of a water tanker. Also this
solution results in costs which are too high. The
presence of calcium compounds in the pool water means that sparingly soluble calcium deposits may form on the surfaces and equipment of the pool . This problem is not solved either by means of the above-mentioned proposals.
The object of the invention is to solve the above- -mentioned problems and to provide an additional filter, for the regular pool filter, which is cheap and efficient to use for removing the discolouration and achieving a clearer or completely clear water in a relatively short time .
The additional filter according to the invention is characterized in
- that the additional filter comprises a plurality of water-permeable filter layers of a thin fabric material contacting each other, and is dimensioned and designed to be fitted around the existing filter cartridge in order to completely enclose the filter cartridge with a main portion, and
- that each filter layer has, on the one hand, larger apertures, wherein some of the larger apertures of the filter layers are completely or partially aligned with each other to form throughflowing passages for the circulating water, and, on the other hand, smaller apertures of varying sizes, that prevent passage of the water-discolouring particles which are distributed within a specific size range, the upper value of which constitutes a limit value for the transition between said larger apertures and said smaller apertures. The method according to the invention is characterized in
- that the circulation through the circulation loop is stopped and the existing filter cartridge is removed from the filter housing,
- that an additional filter, that comprises a plurality of water-permeable filter layers of a thin fabric material contacting each other, is fitted around the removed filter cartridge in order to completely enclose the filter cartridge with a main portion, said filter layers each having, on the one hand, larger apertures, wherein some of the larger apertures of the filter layers are completely or partially aligned with each other to form throughflowing passages for the
circulating water and, on the other hand, smaller apertures of varying sizes, that prevent passage of the water-discolouring particles, which are distributed within a specific size range, the upper value of which constitutes a limit value for the transition between said larger apertures and said smaller apertures,
- that the filter assembly of the existing filter
cartridge and the additional filter is positioned in the filter housing, - that the circulation through the circulation loop is then started again and allowed to continue for a predetermined period of time,
- that the circulation is then stopped and said filter assembly is removed from the filter housing,
- that the additional filter, that is dirty with
water-discolouring particles, is removed from the filter cartridge and is replaced with a new, clean additional filter, and
- that the procedure as above is repeated as required, until an acceptable clarity has been obtained.
Preferably, said predetermined period of time is within 24+6 hours.
Preferably, the procedure is repeated 3-6 times, more preferably 4-5 times.
Preferably, at least some of said larger apertures are of sizes forming said flow passages, in order to allow a high water permeability so that the flow rate in said circulation loop is minimally influenced.
Preferably, said smaller apertures comprise small apertures of varying sizes, preventing passage of water- -discolouring particles larger than about 30 microns, said particles thereby being trapped and retained by the filter layers. Preferably, said limit value is about 600 microns.
Preferably, the additional filter is designed as a sleeve having end portions, defining opposite end openings, wherein the filter cartridge is adapted to be inserted through one of these end openings to form a filter assembly for positioning in a filter chamber in the filter housing. It has surprisingly been found that the additional filter according to the invention removes the discolouration of the pool water in an efficient manner, and this in a relatively short time, usually less than 5 days.
It has not been completely clarified what the actual reason is for the discolouration itself. One theory is that the pool water has a relatively large free surface that is exposed to the surrounding air, causing the oxygenation of the pool water to be increased. Also the circulation of the pool water through the circulation loop contributes to increased oxygenation of the pool water. The metal compounds, which are present in the pool water after having filled the pool, will then be
oxidized, so that various insoluble metal oxides are formed, out of which several are strongly colouring in water, such as primarily iron oxide, copper oxide and manganese oxide. The iron, copper and manganese ions originate from the well water and the piping system in varying amounts. Metallic manganese is dissolved from the metal pipes in the piping system. The respective metal oxide forms small coloured particles, the amount of which is increased concurrently with the oxygenation, so that the pool water, after a short time of use, obtains a visible colour. The colour intensity increases with time, in order to disappear when all initially supplied metal compounds have been oxidized. Furthermore, the well water usually contains calcium compounds, which are also oxidized to calcium oxide, wherein particles of calcium oxide can absorb colouring particles of said metal oxides, which also can contribute to an increased colour intensity and thus an increased degree of discolouration of the pool water. Also chlorine ions or other acidic ions, originating from bactericidal agents added to the pool water, can participate in the chemical reactions leading to the discolouration. In the following, the invention will be described further with reference to the drawings. Figure 1 schematically shows parts of an outdoor pool, which has a circulation loop having a pump that is provided with a filter housing and a pool filter
positioned therein. Figure 2 is an exploded view of the pump of Figure 1.
Figures 3 and 4 show an additional filter according to the invention. Figure 4a is an enlargement in the scale 1:7 of a portion of an outer filter layer of the additional filter in Figure 4.
Figures 5 and 6 show the additional filter of Figures 3 and 4 enclosing the pool filter of Figure 1 partly and completely, respectively.
Figure 1 shows part of an outdoor pool, which comprises a pool 1 and an external circulation loop 2 for purifying the water in the pool with respect to larger, visible, solid particles. The circulation loop contains a pump 3 and a discharge hose 4 and a feed hose 5. The discharge hose 4 is connected to an outlet 6 of the pool 1 and an inlet 7 of the pump 3 , whereas the feed hose 5 is connected to an outlet 8 of the pump 3 and an inlet 9 of the pool 1. The inlet 7 is located vertically above the outlet 8. By means of the pump 3, water is sucked from the pool 1 to the pump 3 via the discharge hose 4 and is returned from the pump 3 to the pool 1 via the feed hose 5. The pump 3 comprises a cylindrical filter housing 10, the central line of which is vertical and which is located vertically above the pump part itself. The filter housing 10 has an internal filter chamber 11, which consequently also has a cylinder shape and which has a central opening (not shown) at its bottom end in
communication with the outlet 8 of the pump 3 through the spaces defined by the vanes (not shown) of the pump 3. Furthermore, the filter chamber 11 has a side opening, connecting directly to the inlet 7 through the wall of the filter housing 10. During operation, the filter chamber 11 is kept sealed by means of a top cover 12, which is screwed to the upper end portion of the filter housing 10. In the filter chamber 11, there is a
cylindrical pool filter 13 in the form of a removable pool filter cartridge, the upper end opening 14 of which is kept sealed during operation by means of the top cover 12, so that no water is allowed to pass through this upper end opening 14 from the outside of the pool filter 13, and the lower end opening (not shown) of which is in direct communication with said central opening in the bottom end of the filter chamber 11, against which the pool filter cartridge 13 lies in sealing contact. The diameter of the pool filter cartridge 13 is slightly smaller than the diameter of the filter chamber 11, so that an annular, free space is formed, between the inside of the filter housing 10 and the outside of the filter cartridge 13, through which water from the pool 1 can be distributed around the filter member 15 of the pool filter cartridge 13, so that the entire filter area can be used for through- flow of pool water through the pool filter cartridge 13 into its internal space.
During the water circulation, larger visible, solid particles, such as insects, pine needles, pollen, small twig pieces, skin pieces, etc., will get trapped on the outside of the filter member 15. Suitably, the filter member 15 is corrugated like an accordion bellows in order to achieve an increased flow area. Figures 3-6 show an additional filter 16 according to the invention, which is applied on the pool filter 15 when required, so that it completely encloses the filter member 15 of the pool filter 13. The additional filter 16 has the shape of a sleeve having opposite end openings 17, 18 with a diameter that is slightly smaller than the diameter of the pool filter 13, in order to form
corrugated end portions 19, 20, abutting against the end surfaces 21, 22 of the pool filter 13, so that the additional filter 16, at its end portions 19, 20 around the end openings 17, 18, is clamped between the pool filter 13 and the top cover 12 and the bottom surface of the filter chamber 11, respectively. The end portions are provided with elastic ribbons, enabling the end openings 17, 18 to be widened so that the pool filter cartridge 13 easily can be inserted into the additional filter 16 through one of these end openings 17, 18. The additional filter 16 is so dimensioned relative to the size of the pool filter 13 that it, with a larger filter portion extending between the end portions 19, 20, will contact the pool filter 13 or be located relatively close
thereto, so that a filter assembly 23 of the additional filter 16 and the pool filter 13 can be inserted into the filter chamber 11 without any problems.
The additional filter 16 is manufactured from two, or preferably more, air and water permeable filter layers of a pliable, non self-supporting, thin fabric material, which e.g. can consist of thin, short and/or long, straight and/or curved filaments or fibres of plastic, e.g. polypropylene, which are bonded together in an irregular pattern with apertures of varying size and shape between the filaments or fibres as is illustrated in Figure 4a. The multilayered additional filter has a high water permeability so that the flow rate of the pool water will be nearly the same as when the additional filter is not fitted on the pool filter 13. In spite of this, the multilayered additional filter 16 will capture and retain water-discolouring insoluble particles of metal compounds, which have been precipitated in the chlorine-containing water in the pool. Each filter layer of the additional filter 16 comprises a first group of larger apertures, ensuring that continuous flow passages through all filter layers are formed, and a second group of smaller apertures, ensuring that the water- -discolouring particles are trapped in the filter layers, wherein these particles are distributed in a size range, where the upper value of particle size constitutes a limit and transition between said first group of larger apertures and second group of smaller apertures . In a trial to investigate the effect of the invention, an additional filter 16 having five separate filter layers of a thin fabric material of the above-described type was used, wherein said fabric material had a basis weight of approx. 20 g/m 2 . The trial showed that the flow rate decreased by only 0.1-0.2 % after the fitting of the five-layered additional filter 16. After running the pump for 1 day, the additional filter 16, which was found to be dirty with particles, was removed. The additional filter 16 was rinsed with fresh water. The rinsing water was collected and the procedure was repeated for an additional period of 4 days, while using an entirely new, clean additional filter of the same type after each day's run. The rinsing water from the five rinses was collected and evaporated to obtain 2.73 g of a dry material of particles, wherein said material was sieved and analysed in order to determine the distribution of the particle size. The result was the following: Sieving analysis
Mesh Microns Residue , grams
28 600 0.07
35 425 0.05
45 355 0.08
60 250 0.09
65 212 1.04
200 75 1.15
325 43 0.11
Bottom 0.14
In this case, said upper value of particle size within said size range is thus about 600 microns. The lower value can be estimated to be about 30 microns (0.14 g passes through apertures smaller than 43 microns) .
During the five days, the discolouration gradually decreased after each day. After five days, no
discolouration was visible to the naked eye. Accordingly, the pool water was completely clear and the filtration with the additional filter 16 could stop, not to be resumed until after the pool later had been emptied completely or partially and then filled to a
corresponding level with fresh water containing metal compounds. The above-reported sieving analysis shows that a larger proportion of the collected particulate material was retained on sieves with a mesh size of 75 microns and above, namely 2.48 g, corresponding to approx. 91 %, wherein said particles thus should be responsible for the largest part of the discolouration of the pool water. Only 5.1 % (0.14 g) pass through the last sieve, having a mesh size of 43 microns. During said rinsing of the additional filter 16, also the pool filter 13 itself is rinsed separately, before it is repositioned in the pump. From this trial it can be concluded that a larger proportion of said smaller apertures preferably should have a size of about 75 microns and below.
The sieved particulate material was collected and
investigated with respect to its chemical composition. A X-ray Fluorescence Spectrophotometer, designated
XRF ARL 9400, was used in the analysis. The following content of different compounds was observed: Compound Weight-%
MgO 0.333
Si0 2 12.51
P 2 0 5 0.914
CI 0.581
CaO 4.64
MnO 28.59
Fe 2 0 3 50.87
In this trial, the added pool water did not contain any copper compound.
It is surprising that the multilayered additional filter does not appreciably reduce the flow rate of the water, at the same time as the small water-discolouring
particles, typically between about 30 and about
600 microns, can be captured and retained by the fabric layers. A probable explanation may be as follows: When several fabric filter layers, e.g. 5 of them, are placed against each other, some of the larger apertures, thus being greater than about 600 microns, will overlap each other completely or partially in certain places, and if the overlap is continuous through all the filter layers, i.e. from the outermost or first to the last or innermost filter layer, the thus overlapping apertures will form a flow passage for water, which accordingly passes through all the filter layers and then the permanent pool filter. Of course, some of the water-discolouring particles may be carried along with this water, but can, however, be captured during the next pass or passage of pool water. Another part of said larger apertures will overlap each other completely or partially in other places, but in a limited fashion so that the channel is blocked by a denser region of an underlying filter layer, which can be the third, fourth, or fifth filter layer. These denser regions of the filter layer exhibit a plurality of smaller apertures of varying sizes, said smaller
apertures thus being smaller than about 600 microns, and which initially let through water but gradually become blocked by particles in the specified size range of about 30-600 microns. It will be appreciated that some smaller particles can pass through apertures in said denser region, having sizes in the upper part of said size range, but then can get trapped in a similar region, which can be situated in the 4th and/or 5th filter layer. What has been described above also applies to a larger aperture, i.e. above about 600 microns, which is present in the first filter layer but lacks overlap with a larger aperture in the second filter layer, then instead having a denser region of the above-described type. The water which has passed the additional filter 16 and which is returned to the pool again accordingly still contains water-discolouring particles, but which will get trapped in the additional filter after one or more additional passes through the additional filter. A removal of an additional filter that has been in operation for 1 day will show particle accumulations on the outside of all layers.
The particle range may vary depending on the ground conditions present in the area in question, where water is collected for the pool. In general, most particle sizes will be in the range of about 30-600 microns. A suitable fabric material is the one used as a plant protection cover in the cultivation of plants, said fabric material being air and water permeable and having a basis weight of about 20 g/m 2 . A fabric material exhibiting larger and smaller apertures of the indicated type, with a suitable area division into regions between them to achieve said effects, can also be manufactured separately, wherein a larger proportion of the smaller apertures preferably have a size of about 75 microns and below. The fabric material is pliable and has a low grammage weight, generally suitably about 15-40 g/m 2 .
Thereby, it is ensured that the filter layers of the fabric material will be pressed against each other and against the permanent pool filter 13 during operation, so that lateral flows between the filter layers will be minimal or even prevented, when the pool water flows in toward the additional filter 16 and therethrough.
Thereby, it is prevented that the particles already trapped in a filter layer, in a denser zone with said smaller apertures, are not carried off by any lateral flows, but are retained until the additional filter 16 is discarded and replaced with an unused additional filter.
Next Patent: AUTOMATIC CHARGE MAGAZINE