PDA

View Full Version : Birdman's Sand/Gravel Filter



birdman
11-02-2007, 01:07 AM
Many people have asked about my sand/gravel filters so here's my construction thread. But 1st, all credit has to go to Kent Wallace. He is the one that originally showed me this type of filter. I build mine different from Kent, but the concept, and operation are the same.
This filter while providing some bio filtration is designed as a pump fed polishing filter. it is the last filter in line before going back to the pond. The water is pump fed in the bottom and filters up through progressively finer layers of gravel then sand. There are two outlets, one to your pond, and one to waste. When you want to flush it, you simply pull the plug from the waste line, put it in the pond line, and turn on your blower. The blower will blow up and dislodge all the trapped waste and flush it up and out the waste line. The progressively finer layers of gravel and sand will stay in place because of their weight and the air flushing going up ward. I am currently using 6 of these filters on my ponds and am very pleased with the results.

OK, Lets build a filter.
Start by cutting the top out of your barrel. Try and make a nice round accurate cut as we will be using this as a template later. Next drill a 3 1/4 inch hole in the center/bottom of your barrel. Use a hole saw for this to get a nice round hole. picture 1 This is for the 2 inch shower drain fitting for the water inlet. Now on one side of the barrel, measure down from the top 4 inches and drill a 3 1/2 inch hole there, using the 4 inch mark as the center of the hole. This will be the outlet to the pond. picture 2 On the opposite side of the barrel drill another 3 1/2 inch hole centered 9 inches down for the outlet to waste. picture 2
Now discard the gasket from your 2" shower drain and using 3M-5200 marine adhesive, install the shower drain in the bottom of the barrel. For the two outlets I use 3 inch electrical male and female adapters. Elec. conduit is different from PVC as the threads are straight cut and they will screw together tightly. Once again using 3M-5200 screw together a male and female adapter in each of the two outlet holes. picture 3 This completes the modifications on the barrel.
We also need a plug for the outlets. Just cut 4 inches of 3 inch PVC and glue a cap on one end.

birdman
11-02-2007, 01:25 AM
Next we will build the air manifold for flushing. Get four 1 1/4 inch elec conduit long sweep 90s and cut 1 inch off each end. picture 5 You will need four 4 way "T"s and one 5 way "T", all 1 1/4 inch for the air manifold. And 4 plugs. Glue the plug into one of the 90 degree legs of the 4 way as pictured. picture 6 These plugged ends will act as legs to keep the air manifold off the bottom of the barrel. IMPORTANT, when gluing this manifold together remember the t legs go down and the 5 way center goes up. Now glue two of the elec. conduit 90s into the 4 way "T"s as pictured, picture 7 Next cut 4 spokes out of 1 1/4 inch PVC 7 inches long. picture 8 Glue two of the 7 inch spokes in opposite sides of your center 5 way, and the last two 4 way "T"s on the ends of these spokes, remembering the center 5 way goes up and the plugged 4 ways go down. Glue the other two spokes in the sides with the elec. conduit 90s. Lay the two assembled sides next to the center piece as pictured. picture 9
Glue the three pieces together. This can be a bit tricky, you have to act fast as your gluing 3 joints on each side and it will take some twisting and maybe force to get them together. Once I get the three joints started I pond the assemble on the concrete floor and they go together tight. If you did right you now have an assembled air blower manifold with the center hub facing up and the 4 plugged legs facing down.

birdman
11-02-2007, 01:31 AM
Now we need to drill a bunch of holes in the air blower manifold. Use a 3/16th bit for this. The holes are drilled at a 45 degree angle on the bottom of the manifold, pointing down and in toward the center. I use 1 inch spacing for these holes. Drill the holes in both sides of the spokes and all the way around the rim. Once again pointing down and in to the center at a 45 degree angle.

birdman
11-02-2007, 01:38 AM
We need a grating to keep the layers of gravel and sand off the bottom of the barrel. You can use the light duty egg crate light diffuser or what I prefer is poly dog kennel floor grating. It is much stronger than the egg crate. It comes in 2 by 4 foot sheets so one will make two of these filter grates.
Take the top of the barrel you 1st cut out, lay it on the ground and lay the dog kennel floor grating over that. I sit on the grating to keep it from moving and using the barrel top as a template cut out the floor grating around it using a hand held jig saw. Now measure from edge to edge to get the center and cut a hole just big enough to fit over your are blower manifold center. Glue in the verticlal 1 1/4 inch pipe for the air blower, just long enough to reach the top of the barrel. This assembly can now go in your barrel. Basicly your filter is done.

birdman
11-02-2007, 02:02 AM
One of the beauty's of this filter is it can go just about anywhere. Since it is pump fed, it can be as far away from the pump or pond as need be. The outlet can supply a waterfall or with 12 inches of height above pond level. can supply a 2" TPR.
Install the barrel where you want it, making sure it's level, hook up your piping and fire it up empty, to make sure there are no leaks. Now that you know there are no leaks shut down the pump and start filling it.
I start out with 3 inches of 1 1/2 inch drain field gravel, then 3 inches of 3/4 gravel, 3 inches of pea gravel, then the sand. Make each layer nice and level.
There are several choices for sand. Kent uses #12 sand blasting sand. Many people like using crushed oyster shell chicken grit for the buffering propriety's. I use fine granite chicken grit. What ever you decide, fill the barrel the rest of the way almost to the bottom of the waste outlet. Don't worry if you get it to full. The 1st time you flush it if it's to full you will just flush the extra out the waste line to the neighbors and you don't care about them anyway.
Now the 1st time you start this up make sure your plug is in the pond side, blocking it and allowing the pump water to go out the waste side. Start you water pump, then your air blower. I recommend a 1 horse spa air blower but some people use large shop vacs. The water will churn, boil, and foam. it will take quite a bit of time and water for this 1st flushing. Keep the air blower going for a few minutes. There's so much water churning it's hard to tell if it's clean or not. When you think your getting close, shut off the air blower and keep flushing the filter to waste until the water flows clear. Then just pull your plug from the pond side, put it in the waste side and your new filter is now in operation. Last pictures are empty filter with plug in the different outlets and air blower installed.
These filters are good for about 2,000 gph flow. If you get to much flow going through it you will start to fluidize the sand and maybe even flow it out to your pond. If you see the sand to start fluidizing just pinch off your pump a little. I like to flush my sand/gravel filters every other week.

Mark_NoVA
11-02-2007, 07:59 AM
Great instructions, Steve! :ernaehrung004:
If you don't mind, I'll copy these links to other useful sand-and-gravel filter threads here, as they're good references to have:

55 Gal Drum Sand and gravel filter/DIY (http://www.koiphen.com/forums/showthread.php?t=36550)
Kent Wallace bactitwist (http://www.koiphen.com/forums/showthread.php?t=60421) (has pics of Robert's method of making them)
Cleaning the EZR filter (http://www.koiphen.com/forums/showthread.php?t=39558)
Sand/Gravel Filter Modifications (http://www.koiphen.com/forums/showthread.php?t=64606)
50 gallon EZR filter (http://www.koiphen.com/forums/showthread.php?t=37116)
Kent?? Sand question for EZR (http://www.koiphen.com/forums/showthread.php?t=37543)
#12 Sand (for sand/gravel filter) (http://www.koiphen.com/forums/showthread.php?t=62207)
Sand Gravel Filter media ratio (http://www.koiphen.com/forums/showthread.php?t=61396)
Filter Sand? (http://www.koiphen.com/forums/showthread.php?t=61200) (contains "Kent's law for optimal fines filtering"!)

Also, an earlier article on these is 'Updraft Barrel Filter' by Burt Ballou in "AKCA Guide to Filters and Pre-filters".

birdman
11-02-2007, 09:09 AM
Great instructions, Steve! :ernaehrung004:
If you don't mind, I'll copy these links to other useful sand-and-gravel filter threads here, as they're good references to have:

".
Yes, please do.

mpageler
11-02-2007, 09:21 AM
Very nice documentation job.

Initially it just didn't make sense that you could wash the media in an upflow direction. I suppose the coarser bubbles (drilled holes versus air stones) tunnel their way through the media, allowing waste particles to follow?

luke-gr
11-02-2007, 10:46 AM
Mike, the big difference is the use of a blower not an air pump. The blower produces huge volumes of air compared to an air pump. Blowers have a 1.5 or 2" outlet which gives an idea of how much air is being forced through.

sirfishmaster
11-02-2007, 10:50 AM
so your inlet is coming from the bottom? I take it that since your holes are facing downward that does not allow the debris to collect?
so essentually the debris being flushed has to make its way up through the layers before expelling out the waste pipe.....about how long does it take flsuhing before clean?

doug

birdman
11-02-2007, 10:57 AM
so your inlet is coming from the bottom? I take it that since your holes are facing downward that does not allow the debris to collect?
so essentually the debris being flushed has to make its way up through the layers before expelling out the waste pipe.....about how long does it take flsuhing before clean?

doug
I usually flush mine about a minute, then it takes a couple of minutes to rinse clear.

rdm757
11-02-2007, 04:08 PM
Off subject, I know, but I LOVE your new avatar birdman! That is one brave gull. Wonder how the shop owner feels about it though!? I'm guessing the gull didn't bother to pay for that bag of chips!

mrpig
11-02-2007, 04:15 PM
Off subject, I know, but I LOVE your new avatar birdman! That is one brave gull. Wonder how the shop owner feels about it though!? I'm guessing the gull didn't bother to pay for that bag of chips!...I'm sure he plopped-down something... but I'm guessing it wasn't money. :D:

birdman
11-02-2007, 05:21 PM
Off subject, I know, but I LOVE your new avatar birdman! That is one brave gull. Wonder how the shop owner feels about it though!? I'm guessing the gull didn't bother to pay for that bag of chips!
I like it too and I don't even who put it there!

vipldy
11-02-2007, 05:24 PM
I like it too and I don't even who put it there!

:rolleyes:

kimini
11-02-2007, 05:48 PM
That video's been going around the Net. It's a real bird, really stealing a bag of chips. The bird gets so much attention that the owner lets it happen because it has gotten his store a lot of publicity.

... it's all fun until the bird's buddies learn the same trick.

birdman
11-02-2007, 09:05 PM
That video's been going around the Net. It's a real bird, really stealing a bag of chips. The bird gets so much attention that the owner lets it happen because it has gotten his store a lot of publicity.

... it's all fun until the bird's buddies learn the same trick.
Works for me, I like stealing food!:yes:

birdman
11-02-2007, 09:07 PM
:rolleyes:
SOOOOOOOOOOOOOOOO
Is this the young lady to whom I am to thank?

Cowiche Ponder
11-03-2007, 01:35 AM
Steve you don't show how the water comes into the filter??

boggen
11-03-2007, 05:11 AM
with mary, which is inlet and which is outlet? and do you have some sort of water manifold in the bottom?

seems like if ya just put a 90 and ran pipe straight down to grating. that you still would get alot of channeling. due to very little to no clearence once weight of rock / sand gets on the grating.

or is grating off set from air manifold, via legs or some sort?

and how are you handling waste. either via wye valve on the outside of filter. or some sort of stand pipe inside the drum?

how much sand has worked it way back down to the bottom. due to so much air?

birdman
11-03-2007, 05:49 AM
with mary, which is inlet and which is outlet? and do you have some sort of water manifold in the bottom?

seems like if ya just put a 90 and ran pipe straight down to grating. that you still would get alot of channeling. due to very little to no clearence once weight of rock / sand gets on the grating.

or is grating off set from air manifold, via legs or some sort?

and how are you handling waste. either via wye valve on the outside of filter. or some sort of stand pipe inside the drum?

how much sand has worked it way back down to the bottom. due to so much air?

The water from the pump comes in the filter in the center bottom of the barrel right under the air blower manifold through the 2 inch shower drain. The air blower manifold has legs built into it (4 way "T"s) to keep it and the grate off the bottom of the barrel.

Water goes out of the filter either to the pond via the top 3" line left side in picture or to waste via the lower 3" line, right side in picture. Look again at this picture, there is a plug that can be moved from waste line to pond line depending on where you want the water to go.

I posted pictures of one of these I cut apart a couple of weeks ago. It had been in service 6 months or so and the layers of sand and gravel were still inplace.

birdman
11-03-2007, 05:52 AM
Steve you don't show how the water comes into the filter??
Yes I do, 1st picture, cutting hole in bottom of barrel for 2" shower drain fitting. The wording shower DRAIN can be miss leading. It's not a drain, but an easy, cheap, DIY-ers bulkhead fitting.

BruceP
11-03-2007, 05:58 AM
Good morning Steve :) You're up early.

Nice design and clear instructions. Is there a reason you used the 'bulkhead' fittings or do you just prefer them over Uni-seals? I may have to make one of these just for grins...... LOL. :)

Mississauga Ponder
11-03-2007, 09:11 AM
instead of using blower to backwash/clean this kind of filter have anyone tried to T the inlet from the bottom of the barrel into the top of the barrel? for cleaning, close the valve going to the bottom then open the valve going to the top the idea is to flash down whatever have been 'filtered' then obviously another shower drain is needed at the bottom. in comparison the blower is 'forcing' the trapped crud upwards. if this will work then you'll save on the blower cost. what do you think?

birdman
11-03-2007, 09:37 AM
Good morning Steve :) You're up early.

Nice design and clear instructions. Is there a reason you used the 'bulkhead' fittings or do you just prefer them over Uni-seals? )
For me the male and female adapters are available locally, less money, and easier to use than uniseals. And sense I offer these filters in Kit form I wanted it to be as easy to assemble as possible. Sometimes uniseals can be a pain th install.

luke-gr
11-03-2007, 09:38 AM
Jocel, I think the agitation of the air is needed. To get a filter good and clean using a gentle flow of water would be nearly impossible I think. It might work for media that can float and tumble but I dont think it would be a good option on these.

birdman
11-03-2007, 09:42 AM
instead of using blower to backwash/clean this kind of filter have anyone tried to T the inlet from the bottom of the barrel into the top of the barrel? for cleaning, close the valve going to the bottom then open the valve going to the top the idea is to flash down whatever have been 'filtered' then obviously another shower drain is needed at the bottom. in comparison the blower is 'forcing' the trapped crud upwards. if this will work then you'll save on the blower cost. what do you think?
I don't think it would work, at least not as good. 1st just reversing the flow will not dislodge waste from the sand. You need something more violent than just water flow. Without the large movement of air your sand would eventually plug and/or channel. This is where the air comes in. Plus if you changed flow directions you would try and force the sand down through the gravel. What you are talking about is your basic swimming pool sand filter.

Mississauga Ponder
11-03-2007, 11:18 AM
luke and steve,

in theory you are using a bit more 'force' (water coming down instead of going up) due to gravity. the force/inertia of the water that let the crud stuck is the same force of water you are using to dislodge them. but again, that's only in theory. i agree that you're actually forcing the sand down wards during cleaning but you will force it up again during normal operation. anyway, just a thought. i guess its worth trying because the benefit out weighs the effort to test.

how'd you know if it cleaned the filter enough? if you were able to get the same dirt when you clean using the blower. test plan: clean the filter using blower. capture the dirt it was able to dislodge from the filter. take a picture. then for the same period clean the filter using water, capture the dirt that has been dislodged, take a picture then compare.

birdman
11-03-2007, 12:14 PM
luke and steve,

test plan: clean the filter using blower. capture the dirt it was able to dislodge from the filter. take a picture. then for the same period clean the filter using water, capture the dirt that has been dislodged, take a picture then compare.
There you go Jocel. Let us know how it works. I can't began to tell you how many experiments I have thrown away because my idea didn't work. But this is how we learn, and develop new things, just like Kent before me, and Burt before him. Someone comes up with an idea and we take it, and refine it to suit our own needs. Then pass it along to others to help them out.

Mississauga Ponder
11-03-2007, 12:53 PM
i'll let you know. but this has to wait until spring.

birdman
11-03-2007, 02:42 PM
i'll let you know. but this has to wait until spring.

Don't blame you, it's cold up your way.

luke-gr
11-03-2007, 06:03 PM
luke and steve,

in theory you are using a bit more 'force' (water coming down instead of going up) due to gravity. the force/inertia of the water that let the crud stuck is the same force of water you are using to dislodge them. but again, that's only in theory.

True, but we are only talking about a few more inches of force. Im still negative on this one....go ahead and prove me wrong. :d: :harhar: