Inspired by Dr. Ronald Shimek's article
on upside down viewing of feeding in the February '03 issue
of Reefkeeping, I started to think of a way to continuously
feed my reef tank. I came up with a simple and (so far) functional
solution after having spent much time thinking about many
complicated, and probably expensive, solutions.
I simply use a 1000 ml polypropylene jar
(Nalgene), placed in one corner on top of the tank, fitted
with a small homemade bulkhead (a drilled nylon screw with
grommets and a nut) connected to a silicone tube that delivers
water just below the surface of the display tank. Inspired
by the more advanced "Geosapper" device featured
recently here in Reefkeeping,
I inserted a bent acrylic tube to control the surge volume
into the bulkhead. From a powerhead in the overflow, I insert
a t-fitting at the output and reduce one of the outlets to
fit a 2 mm silicone tube. The small silicone tube feeds the
jar with tank water (about 2 drops/ sec.) When the water level
in the jar has risen high enough to overcome the backpressure
from the tube connected to the bulkhead, it empties about
100 ml into the tank. This happens about once every hour.
To ensure enough circulation and oxygen in the jar, I have
connected an air pump as well. In the figure I have indicated
the tube dimensions that work for me after a lot of experimenting.
Note that the small (2mm) silicone tube easily gets clogged
and needs to be cleaned at least once a month to secure a
steady flow into the jar. As an alternative to help prevent
clogging, a peristaltic pump (dosing pump) could be used.
I first made the set-up to feed on a drop-by-drop
basis, but discontinued that configuration when I saw that
the dominant Chromis was watching the feeder's outlet
continuously and was chasing all the other fish away from
At present, I use this device to feed Artemia
nauplii (filtered out from a separate hatching cone) and
Nannochloropsis occulata (instant algae), both added
once or twice per day. I have also tried the device with dead
adult Artemia but with limited success, as the nutrients
get washed out and the Artemia tends to sink to the
bottom of the jar. As the fish tend to loose interest in the
repeated feedings of Artemia, perhaps the ideal food
for this device would be something like Golden Pearls of various
sizes, but with lower a nutritional value and some sort of
capsulation. I suppose that a thick gelatin coating would
reduce the leaking of nutrients before the food is captured
and eaten by the animals.
It's my opinion that this device has reduced
the amount of undigested food, and subsequently improved the
water quality in the tank. However, many other parameters
have changed during the same time period, so it is impossible
to address the improvement only to the new feeding regime.
As an alternative one could use a jar with
a bulkhead at the bottom which would be connected to a silicone
tube that goes through a time controlled valve like those
Sirai produces (http://www.sirai.com/inglese/serieP/2vie_NC/2v_ncM.html).
This jar should be filled in the morning and emptied during
the day (no tank water input). This would probably give the
same concentration of food from the feeder throughout the
day, in contrast to the set-up described above which delivers
more and more diluted concentrations of food.
This feeding device works well with live
food such as rotifers, brine shrimp and phytoplankton (dead
or alive), but it can also be used as a dosing device for
many additives. I thought of it primary for feeding my reef
tank, but it would probably also work well for a rearing tank,
delivering a more continuous supply of food for the fry.