Single pump pool cleaning system and method of simultaneously operating a full-function skimmer and multiple cleaning heads

A swimming pool cleaning system includes a pump, a first tube coupling a suction port of the pump in fluid communication with a main drain or mobile cleaning device which draws water and settled debris from the bottom of the pool, and a skimming device including an entrainment nozzle. The entrainment nozzle is coupled by a second tube to a coupling device which diverts a small portion of pool return water pumped from an outlet port of the pump. Most of the pool return water is pumped into a rotary distribution valve, various outlets of which are connected to various pool cleaning heads embedded in an inner surface of the pool. A vacuum canister having a removable cover to allow access to a removable debris trap disposed in the vacuum canister between an inlet and an outlet thereof is coupled between a suction inlet of the pump and the main drain or mobile cleaning device. A single low-horsepower pump produces simultaneous effective skimming, operation of embedded cleaning heads, and trapping of debris in a trap in a vacuum canister.

BACKGROUND OF THE INVENTION 
The invention relates to a swimming pool cleaning system in which a single 
pool pump drawing water only out of a main drain can simultaneously 
operate a skimmer, a leaf and debris trap device in the suction line, and 
a plurality of pop-up cleaning heads disposed in floor and/or wall of the 
swimming pool. 
Intense summer wind/dust storms are common in various parts of the country, 
especially the Southwest desert regions, wherein large amounts of leaves, 
dust, and other debris are deposited in swimming pools, presenting a 
burdensome cleaning problem. Some known pool cleaning systems agitate the 
water to keep dust and debris in suspension in the pool water so that the 
dust and debris are removed by the main pool filter. However, large debris 
blown into the pool by the intense summer wind/dust storms does not stay 
in suspension long enough to be filtered and instead settles to the bottom 
of the pool. 
Typical well known components of a swimming pool cleaning system are 
disclosed in commonly assigned U.S. Pat. NO. 4,322,860 "POOL CLEANING HEAD 
WITH ROTARY POP-UP JET PRODUCING ELEMENT", by Henry D. Gould, issued Apr. 
6, 1982, which discloses indexed rotation pop-up cleaning heads for 
installation in the bottom surfaces of a swimming pool, and U.S. Pat. NO. 
4,523,606 "DISTRIBUTION VALVE", by Charles M. Gould and Andy F. Blake, 
issued Jun. 18, 1985, which discloses a rotary distribution valve that 
sequentially distributes water from the high pressure outlet of a swimming 
pool pump/filter system into the various pop-up cleaning heads. Commonly 
assigned allowed application "VACUUM SYSTEM FOR REMOVAL OF DEBRIS FROM 
SWIMMING POOLS", Blake et al., filed Nov. 29, 1995, Ser. No. 08/564,779 
(U.S. Pat. No. 5,750,022), incorporated herein by reference, discloses a 
vacuum chamber having an access port, an outlet port connected to a 
suction inlet of the pump and an inlet port connected to receive water and 
debris pumped from the bottom of the pool. The above mentioned commonly 
assigned U.S. Pat. Nos. 4,322,860 and 4,523,606 also are incorporated 
herein by reference. 
Another known system is described in the commonly assigned abandoned patent 
application "VACUUM-BOOSTED AUXILIARY SWIMMING POOL DRAIN/FILTER SYSTEM", 
Blake et al., filed Jan. 13, 1992, Ser. No. 07/821,393, incorporated 
herein by reference, and marketed by the Assignee as its QDR (Quick Debris 
Removal) system. That system is similar to the LEAF TRAPPER settled debris 
removal system marketed by Caretaker Systems, Inc., of 
U.S. Pat. No. 4,501,659 entitled "SKIMMER APATUS FOR SWIMMING POOLS" by 
Charles R. Henk, issued Feb. 26, 1985, discloses a skimmer in which all of 
the water returned by the pool pump through the filter to the pool is 
injected through a venturi or entrainment nozzle into the lower portion of 
a skimmer chamber. The water ejected by the entrainment nozzle entrains 
adjacent water in the skimmer body and carries such water through a return 
tube back into the swimming pool. Such entrainment causes surface water of 
the pool to flow by action of gravity into the skimmer to replace the 
entrained water. 
The skimmer device described in the Henk patent was marketed by Hayward, 
Inc. for use in pools in which a bottom port of the skimmer shown by 
reference numeral 12 in FIG. 7 of the Henk patent housing was connected by 
a pipe to the suction side of an auxiliary swimming pool pump. The Hayward 
skimmer was marketed for the purpose of using only its suction port for 
"normal" skimming, and supplementing such normal skimming in a "turbo" 
mode by directing all of the return water into the entrainment nozzle when 
extra skimming was needed. The total amount of water drawn into the 
skimming inlet of the Hayward skimmer when in its "turbo" mode, was equal 
to the amount of water drawn by the auxiliary pump from the bottom of the 
skimmer plus the water entrained by the entrainment nozzle and carried out 
of the return tube along with the pumped water. The amount of pumped water 
typically was in the range from 60 to 100 gallons per minute. To achieve 
simultaneous skimming and operation of pop-up cleaning heads, an 
additional auxiliary pump would have been needed just for the Hayward 
skimmer. This is thought to have been the main reason for the very poor 
market acceptance of the Hayward skimmer. 
It should be appreciated that an owner of a swimming pool having therein 
even the most effective commercially available automatic cleaning system 
occasionally may wish to use a conventional manual pool vacuum sweeper to 
manually vacuum the bottom of the swimming pool and thereby remove 
accumulated debris such as sand, gravel, leaves or the like more 
thoroughly and more quickly than can be accomplished by the automatic 
cleaning system. A conventional manual pool vacuum sweeper includes a long 
flexible hose coupled to a suitable suction port in the pool water 
recirculation system. Note that some settled debris, such as sand or 
gravel, may be too heavy to be effectively moved by the cleaning head jets 
to move it to the main drain. Or, the debris may be too large to pass into 
the main drain and hence into the strainers or filters of the pool 
cleaning systems. 
In all known swimming pool cleaning systems, water drawn through a manual 
pool vacuum sweeper and into a suction port of the pool cleaning system 
passes through the main pump and main filter. The amount of flow of such 
"vacuumed" water is limited by the capacity of the main pump. It would be 
desirable to provide a manual vacuuming capability in an automatic pool 
cleaning system which exceeds the debris holding capacity of the "hair and 
lint basket" of the main pump. It also would be desirable to avoid damage 
to the pump impeller by heavy debris which is manually "vacuumed" from the 
bottom of the pool in the manner described above. 
Until the present invention, there was no available "integrated" swimming 
pool cleaning system using only a single low horsepower pump (eg., one 
horsepower) to simultaneously provide the combination of good skimming, 
effective operation of pop-up cleaning heads embedded in the bottom and/or 
side walls and/or steps of the swimming pool, and removal and trapping of 
leaves and debris from the bottom of the swimming pool, either through a 
main drain or a mobile robotic cleaning device which moved along the 
bottom of the swimming pool. Although such a system would be highly 
desirable, and in fact for years there has been a great deal of motivation 
in the swimming pool/accessories industry to provide such a system at a 
reasonably low installation cost and having reasonably low operating and 
maintenance costs, that need has not been met prior to the present 
invention. 
Note that in prior pool cleaning systems for large pools in which multiple 
skimmers were desired, suction provided by a single low horsepower pump 
had to be divided among the multiple skimmers, and the result usually was 
that adequate skimming could not be simultaneously achieved by all of the 
skimmers from the suction provided by the single pump. 
SUMMARY OF THE INVENTION 
Accordingly, it is an object of the invention to provide an improved 
skimming system for a swimming pool to provide effective skimming that is 
at least as effective as the system described in U.S. Pat. No. 4,501,659 
by Henk while using only a small portion of the full pumping capability of 
a single conventional swimming pool pump. 
It is another object of the invention to provide an integrated swimming 
pool cleaning system which, with only a single swimming pool pump, can 
simultaneously efficiently operate a skimmer, a plurality of pop-up 
cleaning heads in sequence, and a leaf debris removal device which traps 
leaves and debris which have settled to the bottom surface of a swimming 
pool. 
It is another object of the invention to provide an integrated swimming 
pool cleaning system which can accommodate a manual pool vacuum sweeping 
device wherein debris swept from the bottom of the pool does not pass 
through the main pump. 
Briefly described, and in accordance with one embodiment thereof, the 
invention provides a swimming pool cleaning system including a pump, a 
first tube coupling a suction port of the pump in fluid communication with 
a main drain or mobile cleaning device which draws water and settled 
debris from the bottom of the pool, and a skimming device including an 
entrainment nozzle. The entrainment nozzle is coupled by a second tube to 
a coupling device which diverts a small portion of pool "return" water 
pumped from an outlet port of the pump. In the described embodiment, most 
of the pool return water is pumped into a rotary distribution valve, the 
outlet ports of which are connected to various pool cleaning heads 
embedded in an inner surface of the pool. In the described embodiment, a 
vacuum canister having a removable cover to allow access to a removable 
debris trap disposed therein between an inlet and an outlet thereof is 
coupled between a suction inlet of the pump and the main drain or mobile 
cleaning device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to the drawings, swimming pool 1, which includes a bottom 2A 
and inner walls 2B surrounded by a conventional pool deck 7, further 
includes an integrated pool cleaning system. The pool cleaning system may 
include a conventional one horsepower pump 12 having its high pressure 
outlet coupled to the inlet of a filter 13. The outlet of filter 13 is 
connected by a tube 14 to an inlet of a rotary distribution valve 15 of 
the type described in above referenced U.S Pat. No. 4,523,606, the various 
distribution outlet ports of which are each connected to one or more 
pop-up heads 4 disposed in the bottom 2A of the swimming pool. For 
convenience, only one connection between a distribution outlet of 
distribution valve 15 is shown, and is indicated by dotted line 16. 
The suction inlet of pump 12 is connected by a tube 10', a vacuum canister 
9, and a tube 10 to a pair of main drains 3 located in the lowest portion 
of pool bottom 2A. Vacuum canister 9 is connected between tubes 10 and 
10'. Main drains 3 are separated by several feet and coupled by a balance 
tube 3' to prevent vacuum entrapment of a person against the bottom 2A of 
the pool. A removable porous trap 45 (FIG. 3) is disposed between the 
inlet and outlet ports of vacuum chamber 9, which are connected to tubes 
10 and 10', respectively. The removable porous trap 45 can be accessed 
through a removable cover 9A (which forms a vacuum seal with vacuum 
chamber 9), emptied, and placed back in canister 9. This leaf/debris 
trapping canister is described in detail in the above mentioned 
application Ser. No. 08/564,779 incorporated herein by reference. 
Skimmer 5 includes a cylindrical body 21 (FIG. 2) having an inlet 6 that 
extends through vertical wall 2B and opens into the swimming pool so that 
water "skimmed" from the surface 28 of the swimming pool flows into the 
skimmer body 21. A suitable foranimous or porous basket or trap 24 has a 
circumferential upper lip that rests on a circumferential ledge 22 within 
body 21. A conventional removable lid 23 allows access to the inside of 
skimmer 5, so that debris trap 24 can be removed and emptied of floating 
debris which have been trapped or filtered from the skimmed water. 
In accordance with the present invention, one end of a tube 18 is connected 
by a suitable coupler to an entrainment nozzle 20 that extends through the 
wall of skimmer body 21 below debris trap 24. The other end of tube 18 is 
connected by an optional on/off valve 17 and a Tee-connector 18A to above 
described tube 14. A portion 33 of the "return" water flow 34 from filter 
13 is diverted as indicated into tube 18 and flows into entrainment nozzle 
20. The remaining portion 34' of the return water flow 34 flows into 
rotary distribution valve 15 and the pop-up cleaning head or heads 4 
connected to the presently selected outlet port of distribution valve 15. 
(In a typical system, each outlet port of distribution valve 15 feeds two 
or more pop-up cleaning heads 4, and all of the return water from the 
outlet of filter 13 except the diverted water through skimmer 5 passes 
through the presently selected outlet port of distribution valve 15 into 
the pop-up heads 4 connected to that port. Floor cleaning pop-up heads 
typically require 15-20 gallons per minute flow to be optimally effective. 
Step or bench cleaning heads typically require about 5 gallons per minute 
flow to be most effective) 
The water jet 33' (FIG. 2) ejected by narrowed portion 20A of entrainment 
nozzle 20 is coaxially aligned with return tube 19, and and entrains 
"skimmed" water, i.e., pool surface water that has flown through inlet 6 
into the lower portion of skimmer body 21, as indicated by arrows 35. The 
combination of return water 33' ejected from entrainment nozzle 20 and 
water entrained by the jet 33' is forced through return tube 19 and 
returned into the swimming pool as a diverging jet 36, which expands in 
diameter, and, if not deflected, may surface roughly 5-10 feet from 
skimmer 5, producing surface currents which move away from skimmer 5. The 
outlet of entrainment nozzle 20A can be 2-3 inches from the inlet of 
return tube 19. 
FIG. 1 shows in dotted lines a suction tube 26 connected by optional valve 
11 to the suction inlet of pump 12. Valve 11 allows part or all of the 
water pumped into the suction inlet of pump 12 to be diverted to tube 26. 
Suction tube 26 between skimmer 5 and pump 12 was provided in several 
experimental prototype swimming pool cleaning systems for testing 
purposes. Although suction tube 26 is unnecessary to the basic 
operativeness of the present invention, it is described herein both to 
explain an unexpected benefit of the present invention, and also to 
provide a useful alternate embodiment of the invention. Note also that 
tube 26 allows the pool owner to connect a hose to the port of tube 26 
inside of skimmer 5 to manually "vacuum" the bottom of the pool, or to 
pass pool surface water drawn into the skimmer inlet 6 to be filtered by 
filter 13; this might be very desirable to remove oil or the like floating 
on the surface of the pool. 
In the two prototype cleaning pool systems constructed according to the 
present invention, pump 12 is a one horsepower unit, and is capable of 
drawing roughly 60 to 100 gallons per minute of water (depending on the 
amount of water friction present in the particular pool plumbing) into its 
suction port, as indicated by arrows 31, through tubes 10 and 10', debris 
collection canister 9, and main drain 3. The amount of water recirculated 
by pump 12 depends mainly upon how much resistance-producing debris has 
accumulated in the porous filter element 45 in debris collection canister 
9 and the amount of fluid resistance opposing "return" water from the 
outlet of filter 13 through the one or more pop-up cleaning heads 4 
presently selected by rotary distribution valve 15. 
In accordance with the present invention, only a small portion 33 
(typically 5 to 10 gallons per minute) of the 60 to 100 gallons per minute 
of return water from the outlet of filter 13 is diverted through tube 18 
into the entrainment nozzle 20 in skimmer 5. The preferred inside diameter 
of the outlet opening 20A of threaded, removable entrainment nozzle 20 is 
1/4 of an inch for the above indicated 5-10 gallon per minute diverted 
return flow. (A 5/8 inch inside diameter of portion 20A of entrainment 
nozzle 20 also is effective; a larger diameter entrainment nozzle may 
result in a greater amount of skimming than is really needed, at the cost 
of making the pop-up floor cleaning heads 4 ineffective by diverting too 
much of the flow 34 to the skimmer 5 so that not enough is available for 
cleaning heads 4. 
In the two prototypes that have been constructed to date, return tube 19 is 
a 12 inch section of conventional 2 inch PVC pipe. If desired, a deflector 
(not shown) can be attached to the outlet of return tube 19 to change the 
recirculation pattern of water in the swimming pool and/or to prevent jet 
36 from "surfacing". However, such a deflector will decrease the amount of 
water entrained. 
It is believed that the above described skimmer, by using a large diameter, 
short return tube 19 with minimal flow restriction to create back pressure 
against the ejected jet 33' allows the relatively small 5-10 gallons per 
minute diverted flow 33 from the outlet of filter 13 to produce a jet 33' 
that entrains a very large amount of "adjacent" water in the lower part of 
skimmer body 21. This produces surface skimming action approximately as 
effective as that of the skimmer described in the Henk patent and marketed 
by Hayward, Inc, but using a far smaller portion of the pumped return 
water and without necessitating use of the full pumping capacity of a pump 
just to operate the skimmer. As a result, the large remaining portion 34' 
of the return water from pump 12 can be used for simultaneously operating 
pop-up cleaning heads 4 at essentially full efficiency. 
The result is the least expensive, most easily maintained, lowest operating 
cost, fully integrated swimming pool cleaning system yet devised. 
Although it is not well understood exactly how the jet 36 of water ejected 
from return tube 19 improves the skimming of floating debris, it is clear 
that jet 36 does enhance the skimming achieved by skimmer 5 compared to 
the skimming action that occurs if all of the "skimmed" water that flows 
by action of gravity through inlet 6 into body 21 of skimmer 5 replaces 
water drawn through the above described "optional" suction tube 26. In the 
experimental prototypes in which the suction tube 26 was provided for test 
purposes, if all of the water drawn into the suction inlet of pump 12 is 
diverted through tube 26 by valve 11 and valve 17 is turned off (so that 
none of the return water passes through entrainment nozzle 20) so that 
neither jet 33' nor jet 36 exists, then it was observed that the skimming 
of light floating debris that was deliberately scattered on the surface 28 
of the pool water in the vicinity of skimmer 5 was actually less effective 
than was the case when the skimming resulted from the much smaller flow 33 
through entrainment nozzle 20. This was observed to be the case even 
though the total amount of pool surface water entering body 21 through 
skimmer inlet 6 was roughly the same in each case. 
As a possible explanation, it is thought that the jet 36 may improve 
skimming action by helping to set up surface currents in the swimming pool 
that tend to more effectively carry floating debris to the inlet of 
skimmer 5. It also is thought that jet 36 entrains some of the adjacent 
water through which jet 36 passes, as indicated by arrows 37 in FIG. 2. 
Such entrained water 37 then is replaced by flow that causes surface 
currents which in turn enhance the skimming. Observations have shown, 
surprisingly, that such surface currents cause nearby debris that are 
within roughly 12 inches of inlet 6 to be skimmed into inlet 6 much more 
effectively than is the case if all of the water drawn out of the bottom 
of skimmer body 21 is pumped through suction tube 26. Incidently, the 
effectiveness of a conventional swimming pool skimmer is known to be 
highest for floating debris that are located within a few inches (eg., 1-3 
inches) from the mouth of the skimmer. The presence of ambient wind and/or 
swimming pool surface currents caused by the wind and/or swimming pool 
water circulation patterns established by the various water inlets and 
outlets of the pool while the pump is operating can carry the floating 
debris away from the mouth of the skimmer even though a large amount of 
pool water is being drawn into the inlet 6 of the skimmer. The water level 
within the skimmer is maintained at a lower level than the surface of the 
swimming pool by water being drawn out of the skimmer by a suction port on 
the bottom of the skimmer housing and/or by water that is entrained by 
return water being ejected from an entrainment nozzle and carried into 
tube 19 that returns entrained water and pumped return water back into the 
swimming pool below the surface. 
Note that it is not essential that flow 31 be drawn from main drain 3. A 
suction port 41 on the vertical wall 2B of swimming pool 1 can be 
connected to the inlet of debris trapping canister 9. A long flexible hose 
indicated by dotted line 43 can be connected between suction port 41 and a 
"robotic" suction cleaning device 42, such as one marketed under the 
trademark KREEPY KRAWLEY. Even though such robotic suction cleaning 
devices are very effective at cleaning settled debris from the bottom of a 
swimming pool, it is very desirable to have effective simultaneous 
skimming to collect floating debris before it settles to the bottom. 
Thus, the present invention provides efficient simultaneous skimming of the 
surface of a swimming pool without significantly reducing the suction 
applied via tube 10 to main drain 3 or via hose 43 to suction cleaning 
device 42 and without reducing the return flow needed for efficient 
simultaneous operation of cleaning heads 4. Both the pool water surface 
and the pool bottom are thereby kept clean, and the system is no more 
expensive to install, operate, and maintain than ordinary one-pump pool 
cleaning systems. Furthermore, with the present invention there is no 
longer a need for the pool owner to operate a valve to provide full 
suction from the single pump to the skimmer when a dust storm deposits a 
large amount of floating debris on the pool surface, and later operate the 
valve to switch full suction of the single pump to the main drain in the 
bottom of the pool to remove the large amount of debris that usually has 
settled to the bottom. Furthermore, the use of only the portion 33 of the 
return water (instead of suction from the skimmer through a tube such as 
26) prevents the pump from loosing its prime and running dry (which 
damages pump seals and bearings) if the surface water level in the pool 
falls below the level of inlet 6. 
The system of the present invention as shown in FIG. 1 typically could be 
powered by a 1 horsepower pump which, when connected as shown, produces a 
sufficient flow (e.g., approximately 90 GPM (gallons per minute) through 
the pump suction port. However, in the prior art QDR system, a larger 
(e.g., 1.5 horsepower) pump would be required to produce approximately the 
same 90 GPM flow through the suction port and filter because of greater 
friction loss resulting from the plumbing required for the QDR system. The 
system of FIG. 1 therefore circulates the pumped water efficiently as the 
QDR system (or LEAF TRAPPER system of Caretaker Systems, Inc.) with a 
lower cost pump and, significantly, considerably lower electricity cost. 
Table 1 below illustrates how the efficiency of the embodiment of the 
invention shown in FIG. 1 compares to the most competitive prior automatic 
swimming pool cleaning system. That known prior system is referred to as 
the "QDR system", and is described in the above incorporated-by-reference 
patent application "VACUUM-BOOSTED AUXILIARY SWIMMING POOL DRAIN/FILTER 
SYSTEM". The QDR system further includes pop-up cleaning heads such as 4 
in FIG. 1 hereof. 
TABLE 1 
__________________________________________________________________________ 
Portion 
Portion 
Settled 
of of 
Debris 
Return Return 
Removal 
Flow Flow Estimated 
Total Flow Required 
Available 
Skimmed 
Pump Through 
for Skimming 
to Surface 
Pump Return 
Auxiliary 
or Debris 
Cleaning 
Water 
HP Flow Drain 
Removal 
Heads 
Flow 
__________________________________________________________________________ 
FIG. 1 
1 90 GPM 
90 GPM 
5-10 80-85 
70 GPM 
GPM GPM 
QDR 1.5 90 GPM 
50-60 
25-30 60-65 
40 GPM 
System GPM GPM GPM 
Including 
Cleaning 
Heads 
__________________________________________________________________________ 
As Table 1 shows, the system of FIG. 1 draws settled debris through the 
main drains 4 with a high flow rate of the full 90 GPM flow produced by 
main pump 12, whereas the QDR system and LEAF TRAPPER systems removed 
settled debris with a flow rate of 50 to 60 GPM. The system of FIG. 1 
requires only 5 to 10 GPM to produce a surface water skimming rate of 
approximately 70 GPM, so 80 to 85 GPM of high pressure return flow to 
operate the cleaning heads 4 as available. This is in contrast with the 
QDR and LEAF TRAPPER systems, which require 25 to 30 GPM of high pressure 
return flow to the entrainment or venturi nozzle which produces the 
settled debris removal flow, leaving only 60 to 65 GPM of high pressure 
return water available to operate the cleaning heads. The estimated 
skimmed surface water flow rate in QDR systems is approximately 40 GPM. 
Thus, although the system of FIG. 1 requires roughly a third less 
electrical power and a lower cost pump, it provides (1) much higher 
suction of settled debris through the main drain, (2) much higher flow of 
high pressure return water through the cleaning heads, and (3) better 
surface skimming, than the prior art QDR system. 
FIG. 3A shows a conventional VAC LOCK cap 53 which is provided on the end 
of tube 41 (also see FIG. 1) to provide a vacuum-tight seal on the end of 
tube 41 if it is not being used as a vacuum port for connection to robotic 
cleaning device 42 or manual vacuum sweeping device 50. (This VAC LOCK 
device is described in U.S. Pat. No. 4,817,991.) 
FIG. 3B shows an alternative embodiment of the invention in which vacuum 
canister 9 includes a moveable valve plate 54 which can be moved to block 
the flow of water from tube 10 into the interior of vacuum canister 9 if 
vacuum port 41 is being used. This allows the full suction produced by 
pump 12 to be applied to whatever robotic cleaning device or manual vacuum 
sweeping device is connected to vacuum port 41. 
FIG. 5 shows a locking device which can be used to effectively retain lid 
9A on vacuum canister 9 so as to prevent lid 9A from being loosened by 
"momentum hammering" that may occur when pump 12 stops. The locking device 
60,61 includes a steel bar 61 and a circular disk 60 axially mounted on 
the center of bar 61. Each of the opposed ends of bar 61 is lowered as 
indicated by arrow 62A into a vertical slot defined by stationary fingers 
61 and 62. When both ends of rod 61 are lowered to bottoms of the vertical 
slots, rod 61 is rotated in the direction of arrows 64 so that the ends of 
rod 61 pass into a pair of stationary slots 63 which are slightly inclined 
relative to the plane of lid 9A. This forces the lowest point of disk 60 
tightly against the upper surface of lid 9A, locking it tightly into 
place. A cable 65 connected between disk 60 and lid handle 66 prevents the 
locking device 60,61 from being inadvertently misplaced. 
While the invention has been described with reference to several particular 
embodiments thereof, those skilled in the art will be able to make the 
various modifications to the described embodiments of the invention 
without departing from the true spirit and scope of the invention. It is 
intended that all combinations of elements and steps which perform 
substantially the same function in substantially the same way to achieve 
the same result are within the scope of the invention. For example, since 
the described skimmer 5 requires only about 5-10 gallons per minute of the 
return water flow 34, one or more skimmers could be added if the pool were 
large, without excessively decreasing the flow 34' to the pop-up cleaning 
heads 4. 
FIG. 4 illustrates an alternate embodiment of the invention utilizing a 
mini pump 56 to operate skimmer 5. The suction port of mini pump 56 is 
connected by tube 58 to draw water from the pool through inlets 58A and 
58B in the wall 2B (See FIG. 1) of the pool. The pumped water 67 is pumped 
through tube 57 into the entrainment nozzle 20 of previously described 
skimmer 5. FIG. 4B illustrates another alternate embodiment in which the 
suction port of mini pump 56 is connected by tube 58 to a T-connector in 
tube 10' of FIG. 1, producing a flow 67 through tube 57 into entrainment 
nozzle 20 of previously described skimmer 5.