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QUESTION:Is there any guideline on how large (volume) an upflow filter should
be? I am wanting to put one together for my 1300 gallon pond and
was wondering what size container I need -- 30 gallon, 50, 100?
As an aside, what type of container is best? I seen a lot of talk
about the Rubbermade stock tanks, but are there any other popular
choices?
ANSWER: I've made six. One for myself which was redesigned and rebuilt, one for
my Dad on Father's day, then redesigned and rebuilt the next Father's
day, and one for my daughter, completely rebuilt later.
The result is a very cheap, very efficient filter that costs less than
$25.00, and produces nearly crystal clear water. Cleaning the filter is
a 20 minute job about every 2 or 3 weeks.
The final filter is simply a square plastic flower pot, about 14 inches
high and 14 inches on each side (no holes in the bottom). I use 1 1/2
or 2 inch plastic pipe (depending on the pump being used) which I put an
elbow and a short extension on one end, which goes to the bottom of the
pot. The line from the pump is poked all the way to the bottom of this
tube.
Inside the pot, I've cut blue furnace filter (often called horsehair
mats) into squares with a hole near one corner so that the squares fit
over the tube and slide them to the bottom. Usually 4 or 5 squares are
all I use. Then there are 4 layers of blue/white/black air conditioner
filters by Purolator. These are pretty cheap and easily cut from one
$6.00 pad. These have a hole cut for the pipe and layered over the
coarse filters.
These stacks of filter material are cut for a snug fit, meaning slightly
oversize so no water leaks around the edges.
I cut a florescent light grid (1/4 inch square grids, white plastic) to
fit inside the pot by using pliers to break the grid where needed. I
also cut a few out so that the grid fits over the pipe. I put this in
the pot on top of the filters to evenly hold them down and set two
bricks (the kind with holes in them) on top of that to weight it down
against the pressure of the water coming from below.
I fit the whole thing into a plastic tub which has a spillway (in two
cases - my Dad's and my daughters) and in a liner box in another (mine),
so the top of the pot is below the outlet spillway. The spillways pour
water onto the waterfall stone and so the upflow filter gravity feeds
the waterfalls, and is hidden behind them by stacked rocks.
So it looks like this: prefilter mesh pots around pump in pond -->
feeds tube inserted into tube in filter box (hidden behind waterfall)
--> carries water to bottom of box (flower pot) --> water flows up
through coarse blue furnace filter --> then though very fine
blue/white/black Purolator filter material --> though light grid -->
through and around bricks --> overflows pot into tub (or lined box) that
it is sitting in --> and clean water flows out onto top of waterfall
through the tub/box spillway.
Dad and Daughter put a board over the tubs and stack rocks on top of
that (and permanent rock stacks around the tub). Mine is in a permanent
box with pond liner that has stone cemented as facing material and a
large stone for a lid, all part of a stone waterfall.
When I see the bricks rise to the top of the pot (usually tilted one way
or another) then I know it is time to clean the filter. This takes 20
minutes and I don't turn off the pump. I simply lift out the hose,
stick the end on the waterfall rock and then start pulling out the
filter pads and wash them with a jet from a water hose. Lift out the
pot and dump the water, put it all back together and stick the tube back
down the pipe. Walk away in 20 minutes once every 2 or 3 weeks.
The bricks rise because the filter pads are essentially clogged and the
water pressure lifts them and the whole assembly in the pot up. (I
stuff loose foam material around the hose going into the tube to reduce
leakage from back pressure, BTW).
So, how large? Mine is pretty small compared to the two ponds it
feeds. One pond is 6 by 10 feet by 3 ft deep and the other is 5 by
about 14 by 3 ft, all connected together. I have in excess of 15 koi
that are 18 inches long and numerous smaller fish of all sizes and all
kinds, some 38 total last count but I've given some away and had some
babies since, so I don't know.
As I said, the water is clear and has remained so since I went to this
setup. Before this setup, I used an upflow that had a rock layer in a
plastic tub with holes in the bottom that served the function of the
bricks. Was hard to clean and tended to compress the filter pads, so I
decided it was counter productive. The water is cleaner now for some
reason. I can probably read the date on a coin on the bottom.
When the pads are pulled out for cleaning, they are almost
unrecognizable for the gunk collected there, but a little hosing down
does wonders and the water so collected has made my azaleas grow leaps
and bounds.
If you have a filter and collect water from the output of the filter and
also a second glass from the water in the pond, and they look the same,
and both are dirty, your filter isn't doing its job. If you clean your
filter and the water coming out is still pretty dirty looking, you need
a better filter.
The filter I have gives drinking water looking water at the waterfall
(but I don't try it, in case you are wondering). There appears to be
good biological action within the filter pads because the fish seem
healthy and happy. I'm happy too.
We use pumps ranging from 1600 to 2300 GPH in our ponds.
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