GPH for Bog Filter..?

[crsublette]

@Meyer Jordan ... Kratky hydroponic grow method actually uses ZERO flow rate to feed its green-specific crops.... but quite a leap to suggest this is indicative of "nutrient plant uptake" ability... You sir extrapolate far too much from what is actually written so to fit your agenda...


@Mucky_Waters

Hydroponics use a low flow rate due to concise nutrient concentration and organic growth is controlled...

Aquaponics use a higher flow rate due to lower nutrient concentration and organic growth is allowed to use up Oxygen... so, a higher flow rate is needed...

Friendly AP practices what is called "low density" aquaponics... UVI practices what is called "high density" aquaponics... this is why Friendly uses a lower flow rate than UVI... Friendly (due to practicing low density) has a much lower solids passed on to the plant roots..


Higher flow rates also allows more oxygen to disperse...

I believe @addy1 also grows plants that are not typical to survive full water submersion... reason they are able to survive is due to her much higher flow rate....

 

[Meyer Jordan]

@Mucky_Waters Here is some interesting material, better defines what is being talked about here...

and... NO where does it indicate flow rates, or hydraulic retention time, was determined due to "nutrient plant uptake" ability for phyto-filters or wetlands or bogs or whatever one want's to call them....

http://www.deq.state.or.us/wq/stormwater/docs/nwr/biofilters.pdf

http://home.eng.iastate.edu/~tge/ce421-521/ishadeep.pdf

Well, Let's see.

From the first link (Bold font is mine)----

"Bioswales-

Pollutant removal rates increase when bioswales are well maintained, and as the residence time of water in a swale increases. (Page 14)

The effectiveness of bioswales is also dependent upon the retention time of the storm water in the bioswale. The longer the retention time, generally, the higher the removal
efficiency. (Page 14-15)

In this document, the term “Phytofiltration” will be used to refer to the use of vegetation uptake of pollutants in storm water runoff in vegetated strips rather than in bioswales or constructed wetlands.(Page 36)

The flow across the vegetated strip will be in sheet flow and
the vegetation will typically not be a wetland species. (Page 36)

Wetlands-
Should be designed to retain for 24 hours the rainfall runoff from 2-year storm event
(Page 41)

Retention time for the water in a constructed wetland should be a minimum of thirty-six hours. (Page 43)

The second linked document only mentions HRT is passing but does state its importance.

 

[Meyer Jordan]

Hydroponics use a low flow rate due to concise nutrient concentration and organic growth is controlled...

Finish the statement: ....to maximize growth rates.

Aquaponics use a higher flow rate due to lower nutrient concentration and organic growth is allowed to use up Oxygen... so, a higher flow rate is needed...

Higher flow rate in Aquaponics is due to Fish being in the equation.

Higher flow rates also allows more oxygen to disperse...

This, and the previous quote, assumes that non-aquatic plants are being grown. This is not true in wetlands or Phyto-filters where aquatic plants are the only plants utilized. Since aquatic plants have the ability to transport Oxygen to the rhizosphere and create an aerobic cocoon (so to speak), they are not affected by the Oxygen level of the surrounding water.

I believe @addy1 also grows plants that are not typical to survive full water submersion... reason they are able to survive is due to her much higher flow rate....

Not all aquatic plants only grow in full water submersion. And I fail to see the rationale that plants will survive due to a higher flow rate. A little documentation on this, please.

 

[crsublette]

Finish the statement: ....to maximize growth rates.

In accordance to nutrient concentration whether the system is recirculating or flow to waste, then, correct, the flow rate is determined to maximize growth rates...

Flow rates are determined according to nutrient concentration and ultimate goal (i.e., is it recirculating or flow to waste). This is why Kratky method uses no flow rate at all... Dutch buckets much smaller than vertical towers and DWC much higher (due to nutrient dilution) than all the others...

 

[crsublette]

Well, Let's see.

From the first link (Bold font is mine)----

"Bioswales-

Pollutant removal rates increase when bioswales are well maintained, and as the residence time of water in a swale increases. (Page 14)

The effectiveness of bioswales is also dependent upon the retention time of the storm water in the bioswale. The longer the retention time, generally, the higher the removal
efficiency. (Page 14-15)

In this document, the term “Phytofiltration” will be used to refer to the use of vegetation uptake of pollutants in storm water runoff in vegetated strips rather than in bioswales or constructed wetlands.(Page 36)

The flow across the vegetated strip will be in sheet flow and
the vegetation will typically not be a wetland species. (Page 36)

Wetlands-
Should be designed to retain for 24 hours the rainfall runoff from 2-year storm event
(Page 41)

Retention time for the water in a constructed wetland should be a minimum of thirty-six hours. (Page 43)

The second linked document only mentions HRT is passing but does state its importance.

Plant nutrient uptake is not their context (except for page 36, which is a pure phytofilter), and, at best, in a our "bogs", plant nutrient uptake is only ONE of the nutrient removal actors... which those documents talk about these other processes responsible for removing nutrients.

You are twisting their words to suggest their retention (flow rate) text is indicative of plant nutrient uptake efficacy.. and it is not...

Their retention text has a context of cleaning water that is incredibly high TDS, particulate, polluted...

Our pond's water are not (or at least shouldn't be) ... as nasty as a waste water treatment facility...

Our pond water is no where near that polluted that a 24~36 hour retention period could ever remotely be applicable to clean our pond's water...

 

[crsublette]

Higher flow rate in Aquaponics is due to Fish being in the equation.

Yep, that's part of it... and only true for coupled aquaponics...

Maintaining gas exchanges at the root zone so the plants grow better and give extra oxygen in the plant's root zone is also part of it...

I doubt increased flow rate in our bogs would add any extra oxygen, due to the significant organic presence... but... the increased flow rate would definitely maintain a better gas exchange....

 

[crsublette]

This, and the previous quote, assumes that non-aquatic plants are being grown.

Correct.

 

[crsublette]

And I fail to see the rationale that plants will survive due to a higher flow rate. A little documentation on this, please.

Just an observation.... Sorry, no documentation.

 

[crsublette]

@Meyer Jordan .. I agree with ya though... in that ... If there is a quite significant notable nutrient or water clarity problem in a pond, then I would definitely aim to do a quite slow flow rate through the bog...

otherwise... I would use the flow rate that is most aesthetically pleasing since bogs are also a type of water feature for folk, depending on how its built.

 

[Meyer Jordan]

You are twisting their words to suggest their retention (flow rate) text is indicative of plant nutrient uptake efficacy.. and it is not...

The following chart is taken from-
https://www.researchgate.net/public...aquatica_in_an_aquaponic_recirculating_system

It is well documented that plant nutrient uptake efficiency has a direct effect on plant growth rate. The above chart shows that the growth rate begins to significantly decline as flow rates exceed 1.6L/min. This is why HRT is recommended for wetlands at 24-36 hours minimum. It is the plants that are reducing the nutrient and pollutant load in the water just as they do in a garden pond.

 

[Meyer Jordan]

@Meyer Jordan .. I agree with ya though... in that ... If there is a quite significant notable nutrient or water clarity problem in a pond, then I would definitely aim to do a quite slow flow rate through the bog...

otherwise... I would use the flow rate that is most aesthetically pleasing since bogs are also a type of water feature for folk, depending on how its built.

Of course. I felt that it should be mentioned in answer to the OPs original question that the high flow rates generally used in the typical pond "bog" actually create a damping effect on the efficiency of the plants to 'polish' the water. With the high flow rates, the "bog" becomes just a large biofilter with gravel sub-strate.

 

[crsublette]

It is the plants that are reducing the nutrient and pollutant load in the water just as they do in a garden pond.

If it were that simple... then you would see all hydroponic grow methods using a generally accepted standard for retention times that is the same for all grow methods to optimize plant growth... and they do not from what I have read of other operators...

I think page 5 in that document I previously hyperlinked describes it best... (http://www.deq.state.or.us/wq/stormwater/docs/nwr/biofilters.pdf)

"How this is accom-plished is complex. Some pollutants are removed by vegetation uptake, some by natural flocculation from decomposing vegetation, some by just slowing the flow down enough for sedimentation to occur, and some by biota consumption and ionic attraction around the root structure."

 

[crsublette]

The following chart is taken from-
https://www.researchgate.net/public...aquatica_in_an_aquaponic_recirculating_system

View attachment 92287
It is well documented that plant nutrient uptake efficiency has a direct effect on plant growth rate. The above chart shows that the growth rate begins to significantly decline as flow rates exceed 1.6L/min. This is why HRT is recommended for wetlands at 24-36 hours minimum. It is the plants that are reducing the nutrient and pollutant load in the water just as they do in a garden pond.

by the way... in that paper, page 4, table 1... HRT at 1.6 l/min is 2.3 hours...

... and that is dealing with a very highly nutrient concentrated water, likely with a more balanced profile than ours... Obviously, in their particular nutrient profile and setup, the faster flow rates indicates poorer plant growth... I will have to read the paper more closely to better understand why...


Wetlands have a 24~36 hour minimum due to the very significant cleaning job needing to be done on the significantly polluted water...


There is a correlation here...

More polluted the water, the lower the flow rate needed to "clean" the water.


Hard for me to imagine a typical water garden pond will be as polluted as the effluent dumping into a wetland or a hydroponic system... Although... I bet there are some that are close to it. heh.

 

[Mmathis]

Gee, I think I was asking a similar question about a year ago, and all I could think of was "slow, medium, or fast." Y'all answered, "slow," so that's what I shoot for. My brain can't handle the techie stuff.

 

[Meyer Jordan]

"How this is accom-plished is complex. Some pollutants are removed by vegetation uptake, some by natural flocculation from decomposing vegetation, some by just slowing the flow down enough for sedimentation to occur, and some by biota consumption and ionic attraction around the root structure."

And all would exhibit higher efficiency with a low flow rate.