Automatic aquarium feeding device

Food is automatically and periodically dispensed to an aquarium over long periods of time by means of a pivotally mounted arm which has a shallow food containing bowl on one end and which operates directly responsive to evaporation of liquid from a liquid containing cup on the opposite end. A supply of food is placed in the shallow bowl which extends over the surface of the aquarium water. A prescribed volume of water or other liquid having an established rate of evaporation is placed in the liquid containing cup to balance the reciprocating arm by weight. Additional water or liquid in an amount known to evaporate in a given period of time is then added to the liquid already in the cup. As the measured liquid evaporates the food containing bowl will begin to tilt downwardly after an initial period and the food will spill into the aquarium at a preselected time determined by the rate of liquid evaporation. To feed for a period of days, a series of such arms are provided with the liquid cup of each having differing amounts of liquid premeasured to activate the arms after differing time periods.

BACKGROUND OF THE INVENTION 
Aquarium hobbyists have tried many techniques for feeding aquatic animals 
during periods of absence. The primary approach has been a series of 
devices which contain a supply of food from which the fish eat at will. 
The food is not automatically dispensed from these devices into the 
aquarium and, because of differing dietary habits, the fish may or may not 
take the food from such an apparatus. Using this type of device is 
particularly unsuccessful with fish that prefer to eat food after it has 
settled on the floor of the aquarium. 
A second and somewhat more satisfactory approach is disclosed in U.S. Pat. 
Nos. 2,900,022 to Friedman and 2,905,144 to Prigg. Both of these devices 
utilize the theory of liquid evaporation as a motivating force to empty 
food from a container into an aquarium. The patent to Prigg discloses an 
apparatus which floats on top of the water inside the aquarium and, as 
normal evaporation of the aquarium water occurs, a series of trays are 
successively activated at periodic intervals to deposit food into the 
water. Other than size and difference in operation, one disadvantage to 
this apparatus is the necessity of floating a part of the apparatus in the 
aquarium. Water disturbances caused by fish jumping or the malfunction of 
a filtering system which could alter the rate of evaporation, could cause 
the float to activate the feed trays at erratic intervals. 
The patent to Friedman is a device which includes an activating arm tilted 
by liquid evaporation from a container attached to the arm. As the liquid 
evaporates a counterweight causes the arm to rotate slowly into contact 
with each of a series of tripping arms which are attached individually to 
feed trays that tilt to pour food into the aquarium. This apparatus is 
somewhat efficient as long as each mechanism works properly. However, 
misalignment of the activating arm would cause a malfunction; also should 
a trip arm malfunction, the activating arm may become stuck at any 
position and prevent further distribution of food into the aquarium. 
Because of the number of cooperating elements in the Friedman apparatus, 
there is considerable likelihood of malfunction while no one is available 
to correct the problem. 
SUMMARY OF THE PRESENT INVENTION 
The present invention is a simple, but very effective automatic feeding 
apparatus for aquariums operated directly by evaporation of water or other 
liquid having an established rate of evaporation. The device is removably 
attached to the side of an aquarium at times when the aquarium must be 
unattended, and because there are no interrelated moving parts there is 
little opportunity for malfunction and consequent improper feeding. 
Basically, the feeder includes a balance arm pivotally attached at a point 
intermediate the end thereof to a bracket clamped on the side of the 
aquarium, with the balance arm having a feed cup on one end suspended over 
the surface of the water in the aquarium and a liquid containing cup 
attached to the opposite end. 
In operation, the food bowl is filled with an amount of food (of any type: 
flakes, pellets, etc.) equal to one feeding; the liquid cup is filled with 
water to a level whereby the force on each side of the pivot point is 
equal and the arm is balanced. Additional water is then added in an amount 
known to evaporate in a given period of time before feeding is desired. 
When the second, premeasured amount of water has evaporated the food bowl 
will begin to tilt downwardly and the food will spill into the aquarium. 
If more than one automatic feeding is desired additional reciprocating 
arms are pivotally attached to the aquarium and the water levels 
incrementally adjusted to cause activation of the arms at preselected 
intervals, thereby emptying the food bowls at intervals. 
For illustrative purposes the evaporative liquid utilized in this 
disclosure is water. Other liquids with established rates of evaporation 
may be utilized, although none is as readily available or as inexpensive 
as water. 
Construction materials may vary including any lightweight but rigid 
plastic, wood, or metal etc., but the preferred material is any of the 
moldable polymers. The bracket or clamping device is a simple clamping 
spring mechanism which may be clipped to a side wall of the aquarium. 
If a single reciprocating arm is employed for a single feeding it may be 
attached directly to the bracket by a pivot pin or other pivot means. If a 
series of arms is necessary, an elongated pivot pin is mounted between two 
of the upright supports or brackets which are clamped to one side of the 
aquarium. The reciprocating arms are then mounted in side by side 
relationship along the pivot pin in such a manner that the food bowls 
extend over the open top of the aquarium. 
When a multiple apparatus is utilized a pivot stop device is placed to the 
rear of the bracket in a position extending just underneath the liquid 
containing cups. The pivot stop prevents the downward tilting of the 
liquid cups past the horizontal when they are filled with liquid which 
amounts to a weight or force heavier than that of the food bowls. The 
liquid cups thereby rest on the top surface of the pivot stop until the 
liquid evaporates to a predetermined level which will activate the 
downward tilting of the food bowl. 
It is therefore an object of the present invention to provide an automatic 
aquarium feeding device which is gravity activated directly responsive to 
evaporation of a liquid. 
It is another object of the present invention to provide an automatic 
aquarium feeding device which has relatively few cooperating movable 
elements, thereby decreasing the chances of malfunction. 
It is a further object of the present invention to provide an automatic 
aquarium feeding device which may be timed to activate at predictable, 
preselected intervals.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
Referring to FIG. 1, the present invention as illustrated is preferably, 
releasably attached to a side wall of an aquarium A. The feeding apparatus 
10 is set up as shown to activate once daily for a three-day period. The 
apparatus 10 as shown includes three balance arms 15 pivotally attached at 
an intermediate point (as bearing 17) to an elongated pivot pin 20 
extending between two upright supports 25. 
Each of the balance arms 15 includes a relatively shallow, food containing 
bowl 30 which extends out over the surface of the water in aquarium A. On 
the opposite end of the arm is a liquid containing cup 35 which, as 
illustrated, preferably has vertical side walls and is somewhat deeper 
than the food bowl 30 which has sloping side walls so that the food will 
more easily slide out into the aquarium as it is tilted. Although the 
liquid cup 35 may be of any configuration, vertical sides make it somewhat 
easier to establish a rate of evaporation of the liquid being utilized 
according to prevailing room conditions such as temperatures, humidity, 
etc. 
To attach the feeding apparatus 10 to a side wall of aquarium A a spring 
clip 40 (more clearly illustrated in FIG. 2), attached to a vertical 
support means or standard 25 by a tension spring 45, is clamped on the 
aquarium side so that food cup 30 is over the open aquarium. Positioning 
of the apparatus is a matter of choice primarily dependent on whether 
other equipment is emplaced on the aquarium. The only essential is that 
the balance arms 15 be in a position permitting them to activate and 
dispose the food into the aquarium without interference. 
If more than one arm 15 is to be employed two supports 25 may be clipped on 
the aquarium wall in the manner described above. The required number of 
arms 15, dependent on number of feedings desired, are mounted on the 
elongated pivot pin 20 and the pin extended between the two supports by 
inserting it through an aperture 50 extending through the top of each 
support. If a single arm is required, for a single feeding, a shorter 
pivot pin may be inserted through the aperture 50 and through the aperture 
50' on the balance arm. 
The following describes one way of setting the device up for one or more 
delayed feedings. After the supports and arms are emplaced on the aquarium 
wall an amount of food equivalent to one feeding is placed in each food 
bowl 30. Water is then added to the liquid cups 35 to a level that the 
force on the liquid cup side of pivot pin 20 is equivalent to the force on 
the food bowl side. This will establish a balance between the two 
containers. When the arm is appropriately balanced additional water is 
added to the cup 35 in an amount known to evaporate during the prescribed 
period of time before the corresponding food bowl is desired to begin 
tilting. For instance, if water under given ambient conditions is known to 
evaporate at the rate of substantially one drop per hour, then after the 
arm 15 is balanced a drop of water is added for each hour between set up 
time and the selected feeding time; i.e., if feeding time is 24 hours 
away, then substantially 24 drops of water are added to the balanced cup. 
For multiple feedings, water is added to other liquid cups in amounts that 
will evaporate during selected consecutive periods of time. Alternatively, 
each liquid cup and food bowl may be provided with graduations 36, 
indicating approximate amounts for desired intervals. However, room 
conditions cause considerable variations in evaporation rates, and it is 
believed the procedure outlined above will provide more satisfactory 
results. 
To prevent the arms from pivoting downwardly when the additional water is 
added to the cups, a pivot stop 60 extends horizontally behind each 
support 25 at a level which will engage the undersurface of the liquid cup 
35 when the arm 15 is balanced. When multiple arms are utilized a cross 
bar 60' may be laid across the stops 60 to extend underneath and engage 
the centrally positioned cup (cups) 35. 
Activation of the arm 15 will begin to occur when the measured amount of 
water in the liquid cup has evaporated. At that time the arm will reach a 
state of imbalance, the food bowl will tilt downwardly (along the dotted 
line of FIG. 2), and the food will slide out of the bowl into the 
aquarium. It should also be mentioned here that, because most fish food is 
extremely lightweight, the food bowl end of the arm 15 when empty is 
slightly heavier than the liquid cup to insure the downward tilt of the 
arm. 
As mentioned herein, the apparatus 10 does not include cooperatively 
dependent elements. Therefore, when the water or other liquid evaporates, 
gravity alone will naturally cause the food bowl to tilt downwardly and 
empty the food into the aquarium. There is nothing for the arm 15 to 
engage or catch on, and nothing to hinder the emptying of the food into 
the aquarium. One element cannot cause another element to fail and thereby 
cause improper feeding of the fish or other aquatic animal. 
As mentioned hereinabove the feeding apparatus 10 may be made from a 
variety of materials including lighter weight woods, metals, or preferably 
plastic. The synthetic polymers are generally preferred because they may 
be economically molded and are lightweight and rigid, and which do not 
contain chemicals or other elements which might be harmful to the aquatic 
animals if placed in the aquarium. As designed, it is not necessary for 
any of the parts of the apparatus 10 to touch the aquarium water but if 
this should happen inadvertently the plastics are not likely to cause any 
damage to the fish or alter the water conditions. 
Although a preferred embodiment of the present invention has been disclosed 
above, it is obvious that further modifications or alterations might be 
made without departing from the scope of the invention is claimed below.