"Destroyallx" wrote in message
...
i actually live in upstate new york. i was unable to dig anydeeper than i
did without hitting a massive amount of rocks and clay water. i read your
post george, about making a filter with rocks...
im still a little bit lost. ok, so lets say, i have a 20 gallon container,
and a pump (submergeable in my pond - since thats what i have). i fill the
contained 1/2 way? with small rocks/pebbles. and allow water to flow through
this and out .. down my waterfall?? could i do this?
what are some other easy ways to make a filter.
thanx.

You can do it that way, yes. Positive pressure (like you are using) always
works, and should never loses its prime. The drawback is that the pump is
susceptible to getting fouled with debris, which can damage the pump, or the
little foam prefilter for it. I use suction instead simply because of the type
of pump I use. In fact, I prefer suction because my pump doesn't get clogged
that way. By using suction (where the pump is at the end of the filtration
process), it never gets fouled, since it is always pumping filtered water. The
one thing about suction is that the filter housing has to be airtight (or in my
case, completely submerged in water) and below the water line of the pond so
that it never loses its prime.

Oh, and if you use rocks, use rounded quartz pebbles, of about 1/3 of an inch in
diameter or slightly less. I bought prewashed aquarium gravel (not the colorized
kind, the natural rounded pebbles). My filter tank is about 20 gallons
capacity (if you've got the money, you can order a 20 gallon "new" (meaning,
never used) plastic chemical drum online and use it), and it is filled up about
half way with the gravel (which naturally makes it very heavy). In my case,
since it is a suction filter, the intake is on the bottom, but you can put it on
the bottom side of the tank. I drilled a hole on the bottom, and threaded a 90
degree elbow through it. Connected to this elbow on the inside is a basket or
line strainer that you can get at a hardware store for about $10. It sits
upside down from the bottom of the tank, and rises up into the gravel about 4
inches. This allows water to flow into the gravel from the intake line (which
is connected to the elbow on the outside of the tank), but will catch any debris
that happens to make it through the pre-filter (more about that later), and
prevent gravel from falling back into the inlet. My pump is a submersible
emergency pump, not unlike a sump pump, but portable. The top of the filter is
a specially made 8 inch piece of 1/4 inch thick lexan (I used lexan because it
is very strong, and can be drilled easily - I had this made at a glass shop for
about $10). The pump outlet is attached to a fitting that runs throught the
lexan top. I bought a plastic grommet at the hardwatre store for use in running
the electrical line through the top. Then the lexan is bolted in place (the
tank used to be a jacuzzi swimming pool filter that had seen better days - it
had a valve at the top, which I removed, and bolted the lexan top where the
valve used to be). So, in effect, the pump is suspended above the gravel, but
never comes into contact with it, and is far enough above it that it doesn't
suck the gravel into it. It is about 1/4 hp (5 amps/120 volts), and pumps 1400
gal/hour. All of this sits inside the pond and is cover by the rocks of the
water fall.

I use a store-bought pre-filter (the only part I use, besides ther pump that is
actually manufactured - but you can easily make one yourself). The pre-filter
consists of a 5 gallon tub with a threaded top (although it doesn't have to be
threaded), with perforations in the top to allow water to enter, but not fish
and large debris. Inside, there is a porous matt filter that mechanically
filters the water. Below that is a screen-type bag filled with porous lava rock
(small pebble size pieces) that allows "gunk"-eating bacteria to grow in the
pores. This is the first stage of the biological filter. The main filter is
the second stage of the biological filter. Below the bag of lava rocks are
pieces of plastic (you could use small cut pieces of plastic piping) that help
support the filter and keep it from getting jammed in the outlet. The outlet is
on the bottom side, and simple consists of a threaded connector that is bolted
through a hole in the container. The main filter inlet is connected to this
connector.

The pre-filter is easy to clean. I simply use a coathanger wire hooked on the
end to grab the hose and pull it up. I unthread the top, and rinse out the
filter matting. Important. Do not use tap water to clean the matting. You want
the good bacteria to grow in it. Chlorine from tap water will kill the
bacteria, so bail a bucket of water from your pond, and rinse the matting in it.
Then I drain the tub, and re-fill it as I sink it back into the pond.

You can use a small pre-made "cheapy pond filter" on the inlet side of your
submersible, if you can find on e that will fit it. It can act as a prefilter.
Then connect the outlet to the main filter as described above, and let the water
run through the gravel and out a hole, as you describe.

You don't have to use anything this elaborate, however. You can modify what
I've described to work in your system by simply using it the way you described -
that is, connecting the submersible to the filter at the bottom via a hose, and
letting the water rise through the gravel, and out the hole that you have near
the top. Over time, you can add to it, as I have. Eventually, when your pump
dies, I'd consider modifying it to a suction system, as I have. It is easier to
maintain (in my opinion), and your pump will last longer.

A note about pea green water, and string algae. My water was clear all through
last summer, fall and winter. When it got really cold, I turned the pump off
for fear that it would freeze and get damaged. To help with circulation and
oxygen, I bought a large aquarium air pump, and a large airstone, and sunk it
about a foot into the water, then placed a small garbage pail over top the pump
to prevent it from getting wet. It worked fine , and as I said, I used a
de-icer to keep the surface ice-free. If you live in up-state New York, the
de-icer probably would be useless for you unless you get a really large one (but
expect your electrical bill to go sky high), since I suspect the pond will
freeze solid all the way to the bottom. My sister lives on Martha's Vinyard,
and she told me that their 3 feet deep fountain froze solid. I suspect that
you're pond is simply is not deep enough.

Anyway, when it finally started warming up and getting more sunlight, I turned
the pump back on (about the end of February here). So the filter was off for
about two months. About the middle of march I noticed string algae growing on
the side of the pond and on the rocks. After about three weeks, it became an
algae monster, so I killed the algae with an algacide (I used half-strength
since I have water plants and didn't want to damage them. Then I re-seeded the
pond with bacteria. Right now, I can see all of the fish, and can see all the
way to the bottom (45"). It is clear as a bell, and the plants and fish look
great ( I have eight goldfish, four koi, and a really large, hungry albino
catfish). No string algae, and no suspended algae (pea green water). The algae
monster occurred not because the filter doesn't work, but because I had turned
it off. If the filter doesn't have constant water flowing through it, the
bacteria will die rather quickly for lack of oxygen. Some say within an hour,
but certainly within a day. Because the bacteria died, nutrients built up in
the water. When it got warm and sunny enough to turn the filter on, it added
more oxygen to the water, but because the bacteria in the filter was dead,
nutirents built up in the water, causing the algae bloom. Well, you live and
learn. Next winter, I am going to keep it on as much as possible, unless we get
a blizzard, which doesn't happen too often. And then I'll add the bacteria much
sooner than I did this year.

Build you system using mine as a model, if you can. But you don't have to get
as elaborate. The important things to remember are that you need a strong,
resistant, porous substrate for the bacteria to grow on (such as the pebbles),
good water flow through the filter, use some kind of pre-filter in front of your
pump to keep the gunk out, something that is easy to maintain, and seed the pond
with beneficial bacteria that will eat the detritis that always collects in the
pond, and will prevent sludge guild up as well. Using the bacteria, I've never
had to clean my pond out. The bottom stays gunk-free.

I don't know if any of this will help you, but if you want, I can make a
drawing, and send it to you. Good luck.