FROZEN FOOD FEEDER

Before I go any further, I need to mention that as each tank ambient temperatures vary, it takes experimentation to determine just how much water to place in the main body to last for the time interval you wish the food to be distributed over. Usually the first food thawing won't be for about 2 hours.

I used a 4" diameter cylinder 7" long from an old skimmer for the main body.

I used epoxy to make a bottom and to cement a 1 1/4" ID ABS tube 7.5" long that I think was part of a sink drain (thinwall), by placing the epoxy on a piece of wax paper around the ABS tube standing on it's end, and spread large enough out to fully cover the diameter of the acrylic cylinder, but NOT fill in the hole area of the ABS tube. Before the epoxy hardened I placed the acrylic cylinder over the ABS tube so that the tube was centred in the cylinder and pressed it down fully. Once the epoxy had fully hardened I peeled off the wax paper and used a knife to trim the excess epoxy. Now you have to add water to make sure there are no leaks.

As I want the amount of ice to be minimal at the bottom, and tapering up to maximum as it goes up I used a heated razor knife blade to cut circular rings in 1" thick styrofoam to insert into the cylinder around the ABS tube. The bottom ring was cut to fit tight around the ABS tube and the inside diameter of the acrylic cylinder. I cut three more rings with the same OD but progressively larger ID. With these rings inserted into the cylinder it will be a "stepped" taper downward when viewed from the top.

Now, when water is added and frozen, when taken out and allowed to thaw, the bottom layer has NO ice around the tube so anything frozen placed INSIDE the tube will thaw first. As the thawing progresses upwards in the cylinder, the thawing INSIDE the tube will also progress upwards.

Now, we need to make something that will allow placement of food in the ABS tube so it will thaw from the bottom up. If you are planning on daily use of this DIY, you will need to make 7 of these tubes but will only need one of the base cylinder as it will freeze overnight each night.

I used a 7" length of 1" PVC tubing, two end caps for it, a short piece of 3/16" flexible air line tubing, and a longer length of 3/16" rigid air line tubing.

First, I used a 13/64" drill to drill the centre of the two end caps with the first only being drilled from the inside of one cap but only partway through. I did this one first in case I accidentally drilled right through it I could use the second end cap to try again. In any case I wanted to end up with one end cap drilled all the way through and one only part way through, both in the centre of the end cap.

Now, as the end caps will fit very tight and hard to remove, I sanded the outside of the 1"PVC tubing at both ends until the caps still fit a bit snug but am able to turn them off without trouble.

The length of 3/16" rigid tubing needs to be longer than the ABS and PVC tubing by at least an inch or so. I cut 3/4" off the length of rigid tube but reconnected it with about 1/2" of flex tubing. This flex tubing will prevent the frozen food we will be placing in this PVC tube from sliding down the 3/16" tubing into the tank. The cut piece of rigid on the end will be inserted into the centre of the blind hole inside one end cap to keep the rigid tube centred while freezing.

So, assembled, this will have the rigid air line tube inserted into the blind hole end cap with the PVC tubing placed over the air line tube down into that blind hole end cap. Then the other end cap with the hole in it will be placed over and down on the top of the PVC tube.

The frustrating part of this whole thing is preparing the food for insertion into the ABS tube mounted in the 4" diameter acrylic cylinder.

I measure the amount of RODI water the PVC tube holds and then put half that amount into the PVC tube (with 3/16" rigid tube already in place, cap the top of it and lay it horizontal in the freezer. Once it is frozen, I thaw the frozen food and mix it with enough water to equal the other half of the space in the PVC tube and dump that in, shaking it around to distribute the food as even as possible in the length of tubing just as I lay it horizontal again in the freezer.

Once frozen, hold the blind hole end under the cold water tap until you can twist it off of the PVC tube. Then place the PVC tube into the ABS tube in the 4" cylinder and clip a plastic clothes pin on the rigid air line tube to prevent it from dropping through into the tank as it thaws.

When all assembled and placed in a fixture over the tank, as the frozen water in the cylinder thaws at the bottom it will allow the frozen food in the tube to thaw and drop into the tank water. I have ALSO drilled a hole in a plastic prescription bottle cap so that if I want the thaw to happen faster I can run cold water over the PVC unit until I can remove the frozen food totally from that tube and the plastic clothes pin then will be placed on the top side of the bottle cap which will hold the frozen food in the ABC tube but now with some air around the mass.