DIY - Automatic Aquarium Fish Food Feeder in 5 minutes - YouTube

This is a fairly cheap automatic fish feeder bought on ebay. It has a detachable drum that is filled with fish food and you set a switch at the back for either 12 hour or 24 hour cycles. When it is time to dispense the fish food the drum rotates a single turn. As it turns some of the food falls into an adjustable port at the side of the drum and is then dumped into the water.
Standby current is about 0.25mA (250uA) which should give a good battery life.
The plastic gears are very noisy when it does rotate, but I guess that could be useful for letting you know it's doing it's job.
The unit comes with velcro pads and a clamp system for mounting it to your tank.
I don't actually have a fish tank. The reason I bought this was to evaluate it for use in a public art project, part of which involved the daily dumping of a small amount of glitter on a pedestrian walkway.

Automatic Fish Tank Pond Food Feeder Feeding Timer Aquarium New - US$10.99

Eheim Battery Operated Auto fish feeder is among the best performing automatic fish feeders currently in the market. This everyday feeder with its large capacity of 100 ml (3.3 fl oz) is designed to last for up to six weeks of feeding depending on the amount and type of food dispensed. The transparent drum allows you to easily see the remaining food and make the necessary adjustments.

DIY automatic fish food dispenser - YouTube

Adjustable Aquarium Automatic Auto Tank Pond Fish Food Feeder Feeding Timer Using Duckweed (Lemnoideae), you have an endless source of fish food for typical fish in Aquaponics systems, like Tilapia or Goldfish.

This video show how you can easily make an automatic feeding system so your only job will be adjust the amount of food available, maybe once a week. Spending only 4-5 seconds of your life each time. This is a classical DIY where you can use garbage. Any kind of a canal is great. I prefer using a rain gutter.

Duckweed double itself in 4-6 days and float on the surface. So as long as you only have a few millimeter water in the gutter, the Duckweed will constantly push itself into the feeder. The low level of water in the gutter also prevent any fish to escape into the Duckweed grow bed, but allows dissolved fish poo to enter.
A media (gravel is great!) in the bottom of the grow bed, allows bacterias that live naturally in water to convert the fish poo to nutrients for the Duckweed.

For optimal grow rate, a water temperature of 22-27 degrees Celsius (72-80 Fahrenheit) is recommended. The duckweed need a lot of sun and the fish don't, so take this into consideration with your design. I use a 5 meter rain gutter canal as grow bed and I let water from my sump tank drip in at the other end, making a very slow stream and extra aeration to help the duckweed split faster, and to be pushed to the fish tank.

Please watch for a cool DIY automatic fish food dispenser!

In this Instructables I'm going to show you how to build an Automatic Fish Food Feeder. So you don't have to remember to feed your fish daily because ...

Jun 20, 2017 - Automatic fish tank pond food feeder is easy to use