Gph capacity of birdman’s original fluid bed?

[KoiFan84]

I can’t find the max gph of one 55 gallon barrel with the hamster balls anywhere in the thread. Anybody know max gph? Is it dependent somewhat on the amount of K123 media you put in? Also is there a minimum gph for it to work right? Thanks.

[b_erin]

People have told me it is around 2,000 gph, and that above that it will fluidize the sand bed. I am a novice and have not built one though, just the advice I've been given.

[BWG]

This is the fluidized bed barrel filter. Depends on amount of K media, aeration amount and efficiency of discharge pipe to eliminate air on return line. Seem to remember others had flow issues and drilled holes to increase flow and modified return T pipe to vent air. I'd guess 1500 to 2500 gph. There are many old posts on these issues.

[KoiFan84]

This is the fluidized bed barrel filter. Depends on amount of K media, aeration amount and efficiency of discharge pipe to eliminate air on return line. Seem to remember others had flow issues and drilled holes to increase flow and modified return T pipe to vent air. I'd guess 1500 to 2500 gph. There are many old posts on these issues.

Thanks. I’m going to have an alita 40 pump and K3 media. Is the 40 too powerful u think? Obviously the less the media the more flow it can handle right? Drilled holes where? In hamster balls? It will not have a T pipe just a sweep 3” 90 glued onto immediate outside of inlet and outlet electrical fitting… the outlet will be about 2 feet above pond level.

[DragonFireSG]

With gravity flow moving beds, flow capacity is a function of output pipe diameter.
A 55g barrel can flow a heck lot more than 2000 gph if the outlet is large enough.
Since our ponds are recirculating systems, dwell time isn't too much of an issue as long as your media can boil.
When you up the flow rate, the media has a tendency to clump at the outlet if your blower isn't powerful enough, and/or if your means of retaining media has too small a surface area.

This is good reading.

https://www.koiphen.com/forums/showt...91#post2239791

The theoretical gravity flow rate achievable at 2 ft of head with through 30ft of Sch40 3 inch plumbing is about 10,000 gph.
That empties a 55G barrel in under 20 seconds.

https://www.omnicalculator.com/physics/pipe-flow

There isn't really a minimum water flow GPH per se for a moving bed to function. It is just that at low flow rates, you will not be making best use of the installation. Moving beds work best at higher flow rates. This is true for most aerobic type biological filters.

There conversely is a minimum air flow required.

The general requirement is that the media needs to be able to boil for the MBBR to do its job. How much air you need scales with the size and shape of the container, and quantity of moving bed media.

[KoiFan84]

With gravity flow moving beds, flow capacity is a function of output pipe diameter.
A 55g barrel can flow a heck lot more than 2000 gph if the outlet is large enough.
Since our ponds are recirculating systems, dwell time isn't too much of an issue as long as your media can boil.
When you up the flow rate, the media has a tendency to clump at the outlet if your blower isn't powerful enough, and/or if your means of retaining media has too small a surface area.

This is good reading.

https://www.koiphen.com/forums/showt...91#post2239791

The theoretical gravity flow rate achievable at 2 ft of head with through 30ft of Sch40 3 inch plumbing is about 10,000 gph.
That empties a 55G barrel in under 20 seconds.

https://www.omnicalculator.com/physics/pipe-flow

There isn't really a minimum water flow GPH per se for a moving bed to function. It is just that at low flow rates, you will not be making best use of the installation. Moving beds work best at higher flow rates. This is true for most aerobic type biological filters.

There conversely is a minimum air flow required.

The general requirement is that the media needs to be able to boil for the MBBR to do its job. How much air you need scales with the size and shape of the container, and quantity of moving bed media.

Thanks. So basically you’re saying since the outlet pipe is 3” and 2ft above water level that’s going to allow me to not have to worry about overflowing the drum with too much gph right?

[NaturalK]

Thanks. So basically you’re saying since the outlet pipe is 3” and 2ft above water level that’s going to allow me to not have to worry about overflowing the drum with too much gph right?

If you're talking about the outlet to gravity flow back to the pond, then I wouldnt go more than 3k or so. I've had 3in 1ft, that thing overflowed pretty easily. Had to constrict with ball valve

[KoiFan84]

This is the fluidized bed barrel filter. Depends on amount of K media, aeration amount and efficiency of discharge pipe to eliminate air on return line. Seem to remember others had flow issues and drilled holes to increase flow and modified return T pipe to vent air. I'd guess 1500 to 2500 gph. There are many old posts on these issues.

BWG, so did they drill holes in the length of outlet 3” pipe within the barrel?

[BWG]

See my post in ball valve restriction post. It is a major issue .

What is the differential between the height of the ponds surface and the upper water level of the MB filter ? Then add up the length of all pipe from discharge to pond. Include all vertical and horizontal pipe. Size of pipe, is it all the same size? Next list all connected fittings. With this one can get a equivalent pipe length and rough estimate of possible gravity flow of the discharge plumbing. This is only part of the issue. You still have to contend with flow issues of this filter .

Yes - some added additional holes in the ball trying to increase flow. Only will work if your plumbing can handle it .

[DragonFireSG]

Thanks. So basically you’re saying since the outlet pipe is 3” and 2ft above water level that’s going to allow me to not have to worry about overflowing the drum with too much gph right?

See BWG's post.

The system will only flow as fast as the most restrictive part of the return plumbing.
The "hamster ball" for example is often obstructed by media and potentially, debris. It is probably more suited for 2" returns. If you do a 3" return, a long slotted pipe is probably going to work better.

Air ingestion is also an issue with MBBRs. At high flow rates, process air is often pulled into the outlet. If this air accumulates at any high point in the plumbing, it can have a profound impact on return flow rate.
This is of particular concern in longer pipe runs.