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View Full Version : Anbody else try an FBF filter (fluidized bed sand filter) for biofiltration?



Cecil
12-30-2012, 02:36 PM
I've built and used an RBC (rotating biocontact filter) and an MBBR (moving bed bioreactor filter) and now want to build an FBF (fluidized bed sand filter) to compare as I'm doing a presentation on different types of small scale DIY biofilters, cost, and energy use at an aquaculture conference. I plan on building an FBF that has the same specs as a commercial model that sells for about $850.00 in a catalog, which I should be able to build for much less.

The specs are 80 inches in length, 8 inches in diameter, 50 lbs. of sand, and a 15 gpm pump. According to the catalog it's conservatively rated for 2.5 lbs. of feed per day and 127 lbs. of fish.

For my small scale aquaculture applications (which could easily apply to a Koi pond) I use up-flow filtration in a 55 gallon drum with a center drain from the fish tank that enters the bottom to collect settleable solids. Also a u-tube siphon at the top of the drum is directed to the bottom to trap suspended solids in the filter material before directing flow to to all my biofilters. After the biofilters the water is dumped via gravity back into the fish tank from whichever biofilter I use.

Anyway I'm thinking 8 inch PVC will do the trick with end caps with a one foot section coupled near the top that is clear PVC for viewing to adjust the water flow to get the right amount of fluidization. A valve is used in the waterline to adjust flow and a check valve is used to prevent the loss of water and subsequent packing of sand if the pump is shut off.

I searched here and did not find one other than one Birdman built for polishing.

Any thoughts on this? It appears the concept is simple and easily duplicatable. Anyone interested in pictures when I build it, which will be soon?

rayjay
12-30-2012, 06:02 PM
I would be interested. Can you give a link to the catalog you mentioned?

Cecil
12-30-2012, 10:14 PM
http://www.aquaticeco.com/subcategories/2650/QuikSand-Fluidized-Bed-Biofilters

The FB92

BTW I originally had 25 lbs. of media when it should have been 50 lbs. The 25 lbs. was for the model that is 6 inches in diameter. I corrected it in the post.

powerman
12-31-2012, 01:48 PM
I'm interested in seeing your pictures... I was thinking about making a fluidized sand filter myself... I think it would be a really effective means of bio conversion and probably much better than a moving bed with k-1

montwila
01-01-2013, 12:58 AM
Hi Cecil:

Glad you are still at it. Pictures? We love pictures!

How many gallons in your system? 15gpm is 900 an hr. In other words how many times is it being turned over for that 2.5# of feed and 127# of fish to stay healthy and GROW for those resturants.

Good luck at the auquaculture presentation.

catfish whiskers
01-01-2013, 02:11 AM
Ichthius uses fluid bed sand filters in his systems

http://goldfishgarage.blogspot.com/2010/03/gravity-fed-fluidized-bed.html?m=1

http://www.koiphen.com/forums/member.php?9812-Ichthius

Cecil
01-01-2013, 09:33 AM
I'm interested in seeing your pictures... I was thinking about making a fluidized sand filter myself... I think it would be a really effective means of bio conversion and probably much better than a moving bed with k-1

Dan,

Could very well be, however, I'm finding each filter has it's pluses and minuses, i.e., one may have lot of surface area but requires a higher energy signature while another doesn't consume much power but is expensive to build etc.

I'll be happy to share pics and info and soon!

Cecil
01-01-2013, 09:43 AM
Hi Cecil:

Glad you are still at it. Pictures? We love pictures!

How many gallons in your system? 15gpm is 900 an hr. In other words how many times is it being turned over for that 2.5# of feed and 127# of fish to stay healthy and GROW for those resturants.

Good luck at the auquaculture presentation.

Looks like at least a 3X per hour as my basement tanks are only 2 to 3 hundred gallons and I wouldn't put more than 200 lbs. of fish (typically don't go over 100 lbs.) in them so a 2 percent rate of feeding I wouldn't go up to 2.5 lbs. of feed per day.

My fish are not for the food market. They are for the taxidermy market as I bring in my YOY fish I hatch in ponds for the winter for extra growth before putting them back in ponds in the spring. I produce trophy size gamefish and sell and ship them whole frozen.

Cecil
01-01-2013, 09:46 AM
Ichthius uses fluid bed sand filters in his systems

http://goldfishgarage.blogspot.com/2010/03/gravity-fed-fluidized-bed.html?m=1

http://www.koiphen.com/forums/member.php?9812-Ichthius

Thanks for the info!

epse30
01-01-2013, 11:39 AM
Looks like at least a 3X per hour as My basement tanks are only 2 to 3 hundred gallons and I wouldn't put more than 200 lbs. of fish (typically don't go over 100 lbs.) in them so a 2 percent rate of feeding I wouldn't go up to 2.5 lbs. of feed per day.

My fish are not for the food market. They are for the taxidermy market as I bring in my YOY fish I hatch in ponds for the winter for extra growth before putting them back in ponds in the spring. I produce trophy size gamefish and sell and ship them whole frozen.

Talk about a niche market... I wonder how many of the end buyers claim them as their own catches.

webted
01-01-2013, 01:50 PM
They are for the taxidermy market as I bring in my YOY fish I hatch in ponds for the winter for extra growth before putting them back in ponds in the spring. I produce trophy size gamefish and sell and ship them whole frozen.

Hi Cecil:

How does that work? I was under the impression that trophy fish taxidermy was largely a painting exercise on foam blanks? Are these fish used to form the blanks?

Also, what's a YOY fish?

regards,

-t

Cecil
01-02-2013, 12:15 AM
Talk about a niche market... I wonder how many of the end buyers claim them as their own catches.

None. They are used in showrooms and for taxidermy competitions by taxidermists.

Cecil
01-02-2013, 12:18 AM
Hi Cecil:

How does that work? I was under the impression that trophy fish taxidermy was largely a painting exercise on foam blanks? Are these fish used to form the blanks?

Also, what's a YOY fish?

regards,

-t

There are "skin mounts" where the actual fish is used and there are replicas where a mold was made of the fish. Both have to be painted.

montwila
01-02-2013, 12:53 AM
Most of my friends think and laugh about koi shows. However a taxidermy convention/competition!

We humans are amazing at what we will think of next.

Cecil
01-03-2013, 11:51 PM
Most of my friends think and laugh about koi shows. However a taxidermy convention/competition!

We humans are amazing at what we will think of next.

It's all relative isn't it?

mtsklar
01-04-2013, 08:46 AM
Hi Cecil,

Here are a couple of thoughts on the fluidized sand concept.

When the sand is fluidized continously the sand grains will be grinding on themselves. This will polish the grains and be constantly working against any biofilm that you would hope to grow.

The real advantage to a sand filter in system is its ability to trap fines in the water. Static sand beds will provide great water clarity.

powerman
01-04-2013, 10:27 AM
Hi Cecil,

Here are a couple of thoughts on the fluidized sand concept.

When the sand is fluidized continously the sand grains will be grinding on themselves. This will polish the grains and be constantly working against any biofilm that you would hope to grow.

The real advantage to a sand filter in system is its ability to trap fines in the water. Static sand beds will provide great water clarity.

you are right in that static beds of sand trap lots of fines and provide great water clarity, I disagree with your other statement about the bio film being constantly ground off in a fluidized sand filter...fluidized sand is one of the best bio-converters out there... it can even out perform trickle towers in tan removal... and there is so much surface area in a square foot of sand that the footprint can be smaller than other types of bio converters... one of the drawbacks that I found in the information that I found is that they deplete the water of oxygen and the water should be re-oxygenated after the filter...
most filters have plusses and minuses as Cecil stated... costs, difficulty in building, foot print... some filters are better at fines removal and some are better at bio conversion.. and some are a compromise to do both, such as a bead filter.. My filter philosophy is that there are many types of bacteria and that each has a preferred environment that they could thrive in... any material that is non toxic and has pond water flowing through it from a pond with fish, will support bacteria to convert ammonia to nitrite to nitrate... some material is better than others... some methods are better than others... I think that having multiple types of environments in your filtration will give the best overall results .. for instance, I have, after my vortexes and brushes, aerated matting... this is gravity fed... pumps that draw from here and also from a skimmer and mid level source pump water to a bead filter , bakki shower, clarity unit, and two up flow sand and gravel filters with crushed coral and lithaqua as well as sand... these are static filters... the turnover rate is forty five minutes.... I also run a constant trickle of source water equal to 10% or so a day of pond volume... this is on a 14,000 gallon pond....as you would expect from all of this excess filtration my water is quite clear.... the parameters are excellent.... but I realize most people wouldn't want to do all of this...so for a normal person who wants just one filter to do it all, get a bead filter, but please put a vortex or sieve or something ahead of the pump to get the solids out first.... but for someone looking for better ways to skin a cat, try some stuff... showers, moving beds, fludized sand...and static sand for fines removal... sometimes more is better.... or at least it keeps me busy on my obsession so I don't have to keep buying koi.... I have no more room... ( I am planning a new pond but that will be a different thread)

icu2
01-04-2013, 01:37 PM
( I am planning a new pond but that will be a different thread)

:yahoo:


:pullup:

Cecil
01-04-2013, 10:40 PM
you are right in that static beds of sand trap lots of fines and provide great water clarity, I disagree with your other statement about the bio film being constantly ground off in a fluidized sand filter...fluidized sand is one of the best bio-converters out there... it can even out perform trickle towers in tan removal... and there is so much surface area in a square foot of sand that the footprint can be smaller than other types of bio converters... one of the drawbacks that I found in the information that I found is that they deplete the water of oxygen and the water should be re-oxygenated after the filter...
most filters have plusses and minuses as Cecil stated... costs, difficulty in building, foot print... some filters are better at fines removal and some are better at bio conversion.. and some are a compromise to do both, such as a bead filter.. My filter philosophy is that there are many types of bacteria and that each has a preferred environment that they could thrive in... any material that is non toxic and has pond water flowing through it from a pond with fish, will support bacteria to convert ammonia to nitrite to nitrate... some material is better than others... some methods are better than others... I think that having multiple types of environments in your filtration will give the best overall results .. for instance, I have, after my vortexes and brushes, aerated matting... this is gravity fed... pumps that draw from here and also from a skimmer and mid level source pump water to a bead filter , bakki shower, clarity unit, and two up flow sand and gravel filters with crushed coral and lithaqua as well as sand... these are static filters... the turnover rate is forty five minutes.... I also run a constant trickle of source water equal to 10% or so a day of pond volume... this is on a 14,000 gallon pond....as you would expect from all of this excess filtration my water is quite clear.... the parameters are excellent.... but I realize most people wouldn't want to do all of this...so for a normal person who wants just one filter to do it all, get a bead filter, but please put a vortex or sieve or something ahead of the pump to get the solids out first.... but for someone looking for better ways to skin a cat, try some stuff... showers, moving beds, fludized sand...and static sand for fines removal... sometimes more is better.... or at least it keeps me busy on my obsession so I don't have to keep buying koi.... I have no more room... ( I am planning a new pond but that will be a different thread)

Good post Dan and right on the money. Mtsklar you're confusing sand filters for polishing water with fluidized sand filters that are primarily biofilters. There's a difference.

I bought 10 feet of 6 inch diameter PVC today which is more than I needed but I had to buy a minimum of 10 feet. Over $75.00! :rolleyes:They wanted $40.00 each for flat end caps :rolleyes: of which I'm sure I can find cheaper on the Internet.

I was going with the 8 inch but due to cost I think I'll experiment with the 6 inch model.

I'm still going with a 12 inch section of clear pvc for a viewing window. I'll run a 3/4 inch piece of PVC through the center of the top end cap for the inflow using a Uniseal.

Pictures soon once I get all the parts together. I'm thinking I'm going to have my Amish welder weld me an iron ring with a partial plate around it with holes to mount to a piece of plywood and to set the column down into. This should hold the vertical column safely upright next to the fish tank.

Cecil
01-09-2013, 01:38 PM
Update:

I've ordered the rest of the parts I need to build the fluidized sand filter along with the 10 feet of 6 inch PVC I purchased locally along with a Fernco rubber coupler.

I had to order two flat end caps as locally only the rounded are available and special order was almost three times what I ordered them for. I ordered shorter end caps to save money too. I need at least one flat cap for the bottom of the column for obvious reasons. I'm going to have a local Amish welder build me a short iron cylinder I can mount to a base to slide the bottom of the column for stability.

I also ordered one foot of clear thin walled PVC as a viewing window and another Fernco coupler as I realized I need two.

My thoughts with the Fernco rubber couplers are if the clear PVC becomes unreadable from abrasion over time I can easily remove it and replace it vs. if I glued it in with PVC couplers. Actually the PVC couplers are not much cheaper.

I hope to get this thing built next week with a cost per parts total and step by step pics. So far it appears it will be at least a third of the list price for a commercial unit of the same specs.

If I could have found only 5 feet of six inch PVC I would have saved $38.00 vs. the 10 foot minimum! All the big box stores only go up to 4 inch and you have to order a pallet of six inch for a special order!

Ichthius
01-10-2013, 07:06 PM
http://goldfishgarage.blogspot.com/search?q=fluidized here are all my fluidized posts from my blog.

In terms of ease of use, construction and NH3 conversion nothing can touch a fluidized bed.

I have 4 at work with about 10 tons of sand in each one for 81 acres of surface area each!

Cecil
01-10-2013, 10:39 PM
Wow! Ten tons of sand in each!

Ever have any issues with start up after a shut down or with biofilm building up on the top of the sand?

I'm confused though. From your blog it appears you use fine glass beads instead of sand? But above you say sand.

If what is in your hand on the blog are glass beads where to you get them?

There is a place near me that manufactures windshields. Is this the raw product for producing the windshields?

Ichthius
01-11-2013, 01:05 AM
You need to limit solid waste going into the beds or heterotroph will take over and clog up the bed. You want thin film autotrophs in the fluidized bed. You'll get some heterotrophs on top of the bed feeding on dead autotrophs but that easy enough to siphon off.

Glass beads can be obtained from sand blasting or some paint supply places. They are perfect spheres so the fluidized and restart easier than a jagged natural sand grain but either works.

Cecil
01-11-2013, 10:56 AM
Thanks. Any particular size or type of glass beads I should ask for?

Ichthius
01-12-2013, 03:37 PM
Sorry I don't have an exact product to recommend as My glass beads came with some equipment I bought used.

Each vessel ad flow rate will behave differently. Fine sand/beads have more surface are per volume but larger media will be heavier to lift and will stay in the vessel better.

Don't worry they are fun to experiment with and make it clear if possible, the sand flowing is fun to watch and you can trouble shoot better.

What GPH or GPM are you processing? What is the size of the system and bioload?

Cecil
01-14-2013, 01:27 AM
What GPH or GPM are you processing? What is the size of the system and bioload?

I'm following the specs of a Quicksand filter in the Pentair/AES 2013 catalog pg. 275 that is 6 inches in diameter, 70 inches tall and uses a water pump of 10 gpm + or - 20 percent. Mine will be made of schedule 40 PVC with a 12 inch section of thin walled PVC for viewing. The specs call for 25 lbs. of sand and I'm going with a 50 percent expansion rate. Pentair/AES rates it conservatively at 65 lbs. of fish and 1.25 lbs. of feed per day.

This one will be for a 4 foot diameter 200 gallon circular tank with a center drain and u-tube siphon and clarifier tank. I usually overwinter YOY fish in small tanks like this.

Cecil
01-16-2013, 07:24 AM
Update: Still waiting on the final parts.

I'm wondering if it wouldn't be acceptable to plumb in the water inlet in the bottom side vs. the top center -- and down -- the way it appears to be conventionally done? I ask this because since the top of the filter is so much higher than the pump there could be substantial head loss. I would still attach an elbow at the bottom to direct flow upward.

Thoughts?

Rich L
01-16-2013, 11:01 PM
The head between the top inlet pipe and the water contained in the tube will balance out. one way or another you will only be raising the water once.

I've used a lot of FBs, they are so convenient to put together with parts on hand and a bag of sand. I have been entering the tube from the bottom, with a stand or the side down there. Dropping it from the top is fine. The trick is to have true plug flow when the water raises the sand. Most just put several inches of 3/8 or 1/2" gravel so the water is forced to balance before entering the fluidizing bed. The entrance from the side needs to be 'distributed to lessen the work the gravel does in creating plug flow.

Install a check valve at the inlet. If the flow is shut off and the head in the tube is greater than the head feeding it the water will back up. If you don't want to install a check valve on the input, install the tower so you can later when you find out why I suggested this.

There are many advantages to the small size. I in the 90s constructed a small bubble bead and fluidized bed for a 1000 gallon med/quarantine tank. I wanted to keep the tank fully functioning in the winter and didn't want the filter system outside the well insulated med tank. The FB was made from a 30" piece of 4" PVC. That's a much more effective than the small manufactured filters we see.

I still have it on hand and use it when friends need to keep a heavy load in a tank.

I will usually set the filter in a barrel to allow the finer sand to settle before returning to the pond. There's a lot initially and I don't return it to the filter as it will just come right back out. The rejected sand tapers off but there will always be a little more because the scouring that clears the old bacteria also grinds the particles down.

If you're making it out of PVC, use the thin walled drain PVC. It's cheaper and easier to get the flat end cap. (I only use a cap on the bottom.)

Locate some wholesale irrigation companies near you. They will have a selection to die for and are much cheaper that buying elsewhere. Ewing irrigation is right down the street from me. They have an extensive network throughout the country so see if one is near you.

Their web site is www.ewing1.com and their catalog is on line. You may also like to get them to send the paper one to you. There is a wealth of technical information in the catalog as well as charts & tables such as pipe and equivalent fitting flow charts.

While you're there look through the Resources tab. You will find other info some useful to us and some not.

There are other big wholesale companies that may be near you or at least close enough to keep shipping costs down.

Get a reducer fitting and grind out the seat ridge inside so the pipe will pass on through, Run it down so there is 2 or 3" sticking out on the inside of the fitting. The larger diameter will lower the water's velocity and you won't have to spend so much time purging it out of the sump. Most of the exiting sand(after the original purging) will settle in that fitting and be easier to siphon out. Or you could drill & tap a hole at the bottom ot the mini sump and install a small ball valve; but I'm not that smart.

For the fellow who was worried about stripping the bacterial slime, that's one of the advantages of this and air fluidized filters. Growing bacteria are much more effective compared to mature bacteria. Also, you will have to work very hard to strip all the slime away. There will remain a thin coating of slime, with a young population.

The plastic media sounds interesting but I don't see it working well as a water fluidized bed unless it's very heave and won't be carried out. We could cap the filter with a screen but how will you keep it from gathering around the exit. Unless you are using the trapped media as a particle filter. Let us know, you might start us in another direction.

Rich L

Cecil
01-17-2013, 05:19 AM
Rich,

Thanks for the info. I'm definitely installing a check valve.

Cecil
01-21-2013, 01:28 AM
Still waiting on the end caps and 12 inch section of Clear PVC.

duanes
03-29-2013, 08:54 AM
I built a small FB for indoor use, it is 8" clear PVC, about 4' tall from plans in FAMA, at first it was pressurized (had a top). I found sand would clog the influent pipe during power outages even with a check valve. and was a pain to take apart and clear the plug. I removed the top, and moved the outflow to a few inches below the top. Works fine, and is easier to clean out if plugged.
For sand I've been using aragonite as an aid to buffering alkalinity, and replace a little every few months as it is worn out or dissolved. It tends to color the water a milky white for a day or 2, but clears.
As for the bio film break off, one of the main positives is the constant agitation breaks off weakened bacteria only allowing the most robust to live in the constantly moving environment.
And the sand grains do tend to smooth out over time, so replacing a little sand is a good idea.
http://i70.photobucket.com/albums/i97/dstuer/fluidizedbed/02-16-07_1705.jpg
http://i70.photobucket.com/albums/i97/dstuer/fluidizedbed/02-16-07_1704.jpg