Results 1 to 19 of 19

Thread: When does diminishing marginal returns control in increased gallons per hour speed?

  1. #1
    DIYFK member Homeslice's Avatar


    Join Date
    Nov 2018
    Location
    Houston
    Posts
    22
    Post Thanks / Like

    When does diminishing marginal returns control in increased gallons per hour speed?

    You pretty much always see increased gallons per hour of water flow resulting in increased filter ability/capacity. But, as for biological filtration, when does diminishing marginal returns prevent an increase in more gallons per hour from really resulting in increased filtering capacity? In other words, if water is pumping through a filter at 1 billion gallons per hour, I would guess that would add no material filtering capacity than if water was flowing through it at 1 million gallons per hour - the ability of the bacteria to filter is already maximized at 1 million gallons per hour and, almost certainly, long before that. At what point does say "OK, this is filtering at XXXXXX gallons per hour, adding more that that is probably worthless."

    Thanks!

  2. #2
    DIYFK member Nil13's Avatar


    Join Date
    Jun 2017
    Location
    CA
    Posts
    51
    Post Thanks / Like
    Increased flow does not equal increased filtration. Increased medium volume equals increased filtration and increased volume typically requires increased flow rates to maintain the same dwell time.

    Sent from my SAMSUNG-SM-G890A using Tapatalk

  3. #3
    DIYFK member Meep's Avatar


    Join Date
    Oct 2013
    Location
    Planet Earth
    Posts
    3,331
    Post Thanks / Like
    Click here to enlarge Originally Posted by Homeslice Click here to enlarge
    But, as for biological filtration, when does diminishing marginal returns prevent an increase in more gallons per hour from really resulting in increased filtering capacity?
    That is a moving target based on many variables unique to every situation and those variables are also in constant flux... Aim high and hope the buffer never gets exceeded...

    Since it's a moving target but there is a median, most will aim for two or three times the flow rate that is necessary at the median levels, then as things clog up and slow down or there is a spike in toxins that 2-3 times buffer will be able to absorb the difference above the median...

    At what point does say "OK, this is filtering at XXXXXX gallons per hour, adding more that that is probably worthless."
    When an ongoing and constant test of water returns zero nitrites and ammonia, even after episodes like overfeeding and over time as the flow rate diminishes due to clogging and obstructions or wear and tear on the pump...

    Increased flow does not equal increased filtration. Increased medium volume equals increased filtration
    It's a combination of both, the flow rate dictates the delivery rate of food for the bacterial colony if there is not enough food to support more bacteria, increasing the available space for bacterial growth will have little effect as the food source limits the bacterial colony size and on the flip side if there is not enough media for the colony to expand anymore increasing flow rate will also have little effect as the bacteria will have nowhere to colonize... There is a balance that has to be made between the bioload of the tank, the flow rate, and the bio-media volume... Having too much flow rate (less absurd rates) and/or too much media is not detrimental, but either too little flow rate or too little media will have a detrimental effect...

  4. #4
    DIYFK member Nil13's Avatar


    Join Date
    Jun 2017
    Location
    CA
    Posts
    51
    Post Thanks / Like
    It's a combination of both, the flow rate dictates the delivery rate of food for the bacterial colony if there is not enough food to support more bacteria, increasing the available space for bacterial growth will have little effect as the food source limits the bacterial colony size and on the flip side if there is not enough media for the colony to expand anymore increasing flow rate will also have little effect as the bacteria will have nowhere to colonize... There is a balance that has to be made between the bioload of the tank, the flow rate, and the bio-media volume... Having too much flow rate (less absurd rates) and/or too much media is not detrimental, but either too little flow rate or too little media will have a detrimental effect...
    Sure you want to match your flow rate to your volume of medium. That's dwell time. But it doesn't change the fact that how much filtration a filter is capable of is determined by the volume of medium (really surface area of the volume of medium), not the flow rate. Like you said if the medium is full up, increasing flow does nothing.

    I would argue that having too much flow is detrimental but to the bank account not the tank.


    Sent from my SAMSUNG-SM-G890A using Tapatalk

  5. #5
    DIYFK member Homeslice's Avatar


    Join Date
    Nov 2018
    Location
    Houston
    Posts
    22
    Post Thanks / Like
    "But it doesn't change the fact that how much filtration a filter is capable of is determined by the volume of medium (really surface area of the volume of medium), not the flow rate. "


    Come on guys, I know yall are trying to make a point, but a statement as to how much filtration a filter is capable of is not determined (in any part) by flow rate just can't be right. What if flow rate is 0.0000000001 gallons per hour? Obviously, the bacteria are going to be oxygen and raw material (ammonia, nitrite) starved continuously because the flow is so slow. Flow is most certainly very relevant (at least up until you get "enough") to determining how much filtering can be done by the bacteria.

    So has any real thinking (testing with numbers maybe?) been done as to real numbers - how much flow is not enough, how much flow might be optimal, how much flow is too much, etc.?

    Thanks!


  6. #6
    DIYFK member HillbillyHomer's Avatar


    Join Date
    Sep 2012
    Location
    mo
    Posts
    2,550
    Post Thanks / Like
    Click here to enlarge...Your chasing a rainbow...Click here to enlarge

    See quote
    Click here to enlarge Originally Posted by Meep Click here to enlarge
    That is a moving target based on many variables unique to every situation and those variables are also in constant flux

    E.G. My 30 gal heavily planted tank with a small bioload at 79.2F will need X GPM and Z filtration to be "optimal".
    Now lets say we teleport my tank to Meeps house. His water is WAY! different than mine.
    There is no way to tell what the tank will need to bring it back to being OK let alone "optimal".

    And the water is just One variable!

  7. #7
    DIYFK member Meep's Avatar


    Join Date
    Oct 2013
    Location
    Planet Earth
    Posts
    3,331
    Post Thanks / Like
    Click here to enlarge Originally Posted by HillbillyHomer Click here to enlarge
    Now lets say we teleport my tank to Meeps house. His water is WAY! different than mine.
    There is no way to tell what the tank will need to bring it back to being OK let alone "optimal".
    Your tank would be diatom hell... While I have for now accepted the fate of my other tanks until I invest in an RO system, I 'attempted' to bring the betta tank around 4 weeks ago, tore the entire tank down (but preserved the established and cycled filter bio-media)... Scrubbed everything down and even bleached the entire thing and bleached the gravel so it was all diatom free, set it back up (skipped the fake plants for now as they are a hassle to re-clean) filled it up with my well water, two weeks later I did about an 80% water change with my well water and here is what it looks like after only 4 weeks... Click here to enlarge Going to tear it down again over the Xmas holiday and buy some RO water (and add trace elements) since it's a small tank and see how that goes...

    20181219-170717.jpg

  8. #8
    DIYFK member HillbillyHomer's Avatar


    Join Date
    Sep 2012
    Location
    mo
    Posts
    2,550
    Post Thanks / Like
    DAM!

  9. #9
    DIYFK member Nil13's Avatar


    Join Date
    Jun 2017
    Location
    CA
    Posts
    51
    Post Thanks / Like
    Click here to enlarge Originally Posted by Homeslice Click here to enlarge
    "
    Come on guys, I know yall are trying to make a point, but a statement as to how much filtration a filter is capable of is not determined (in any part) by flow rate just can't be right. What if flow rate is 0.0000000001 gallons per hour? Obviously, the bacteria are going to be oxygen and raw material (ammonia, nitrite) starved continuously because the flow is so slow. Flow is most certainly very relevant (at least up until you get "enough") to determining how much filtering can be done by the bacteria.
    You are correct that if you flow very little to a big filter, the filter won't be capable of much biofiltration in that ultra-low flow state. However the maximum filtration capacity is determined by the amount of surface area in the filter not the flow through the filter. You could flow that same ultra-low flow rate through the filter but effectively increase the hydraulic loading of the filter by recirculating the water within the filter, bypassing the tank altogether to increase the effectiveness of the filter with a low flow rate.

    It is tricky to give you an answer because the ideal flow rate is based on the type of filter (trickle, moving bed, etc) and the amount of media. You are correct that there is a point of diminishing returns where you get less filtration after a certain flow rate but it's different for different types of filters. If you want to find scholarly research on the subject, you'll have to specify the type of filter and you'll want to know the "hydraulic loading rate". The hydraulic loading rate is the relationship between the volume of water flowing through the system in a day and the surface area of the filter. So it's (m3/m2) per day. Iirc, there is research showing that for a trickle filter the point of diminishing returns is a hydraulic loading rate of around 3.
    Now when it comes to figuring out how much capacity is needed, the important factor is the feed load and how much nitrogen is in the feed. What you'll want to search for is "Total Ammonical Nitrogen" or TAN. For a trickle filter the TAN conversion rate is probably going to be about .25g N/m2/d.

    And you'll want to search on Google scholar.



    Sent from my SAMSUNG-SM-G890A using Tapatalk

  10. #10
    DIYFK member Nil13's Avatar


    Join Date
    Jun 2017
    Location
    CA
    Posts
    51
    Post Thanks / Like
    Meep, do you have a lot of silicates in that well water?

    Sent from my SAMSUNG-SM-G890A using Tapatalk

  11. #11
    DIYFK member Meep's Avatar


    Join Date
    Oct 2013
    Location
    Planet Earth
    Posts
    3,331
    Post Thanks / Like
    Click here to enlarge Originally Posted by Nil13 Click here to enlarge
    by recirculating the water within the filter, bypassing the tank altogether to increase the effectiveness of the filter with a low flow rate.
    You are really playing semantics to back your point now, fact is when you 'recirculate' water over the filter you are literally increasing the flow rate over said filter by the most basic definition of the flow rate over the filter... When you are measuring flow rate over the media, it's a gross number, not a percentage of new vs recirculated water...

    Example, if you filter 1 gallon of the tank and recirculate that same 1 gallon through the filter 9 more times in an hour before returning it to the tank, the flow rate across the media is 10 gallons/hour, not 1... What would be 1 is the turn over rate of filtered water returned to the tank, not the flow rate over the filter media...

  12. #12
    DIYFK member Meep's Avatar


    Join Date
    Oct 2013
    Location
    Planet Earth
    Posts
    3,331
    Post Thanks / Like
    Click here to enlarge Originally Posted by Nil13 Click here to enlarge
    Meep, do you have a lot of silicates in that well water?
    Yes, apparently a boatload with some more added for good measure... I have yet to test it to find the exact amount but will be doing that in due time, just another test kit to buy that I have not got around to yet...

  13. #13
    DIYFK member Nil13's Avatar


    Join Date
    Jun 2017
    Location
    CA
    Posts
    51
    Post Thanks / Like
    In a closed loop system like an aquarium the difference between hydraulic loading and flow rate is inconsequential, but a lot of the research includes open wastewater treatment where the difference matters wrt understanding the research. Also, some aquaculture researchers are working with what they call shunts to get cleaner outflow from the filter with the same amount of flow through the main tank.

    Sent from my SAMSUNG-SM-G890A using Tapatalk

  14. #14
    DIYFK member Nil13's Avatar


    Join Date
    Jun 2017
    Location
    CA
    Posts
    51
    Post Thanks / Like
    Meep, have you tried running some phosguard in the filter? Is there a filter on that?

    Sent from my SAMSUNG-SM-G890A using Tapatalk

  15. #15
    DIYFK member Meep's Avatar


    Join Date
    Oct 2013
    Location
    Planet Earth
    Posts
    3,331
    Post Thanks / Like
    Click here to enlarge Originally Posted by Nil13 Click here to enlarge
    Meep, have you tried running some phosguard in the filter?
    No, because dollar for dollar it's not an economical solution for the number of tanks (gallons of water) I have, and would require constant weekly testing with every water change to see if the stuff is exhausted, an RO system and re-mineralization is where I'm heading, just a lot of other stuff on my plate that takes priority over the fish tanks looks right now...

    Is there a filter on that?
    Yes, a built in filter system, that I have redone with a custom filter pad and about 2 cups of ceramic media, plenty of turn over and filter capacity for a single betta...

  16. #16
    DIYFK member Nil13's Avatar


    Join Date
    Jun 2017
    Location
    CA
    Posts
    51
    Post Thanks / Like
    Homeslice, what are you thinking about doing? What sort of filter are we talking about?

    Meep, have you tried nerite snails on those diatoms?

    Sent from my SAMSUNG-SM-G890A using Tapatalk

  17. #17
    DIYFK member Meep's Avatar


    Join Date
    Oct 2013
    Location
    Planet Earth
    Posts
    3,331
    Post Thanks / Like
    Click here to enlarge Originally Posted by Nil13 Click here to enlarge
    Meep, have you tried nerite snails on those diatoms?
    No, and I won't be, as I despise snails infestations more than the diatoms...

    The only way I will willfully have snails in my tanks is if it's a dedicated snail tank and/or a dedicated kids fish tank, any found in my general tanks are public enemies...

  18. #18
    DIYFK member Nil13's Avatar


    Join Date
    Jun 2017
    Location
    CA
    Posts
    51
    Post Thanks / Like
    Click here to enlarge Originally Posted by Meep Click here to enlarge
    No, and I won't be, as I despise snails infestations more than the diatoms...
    Nerites don't reproduce in freshwater though they live there just fine. The baby snails need brackish water to survive. So there is no chance of infestation like with those damn bladder snails. They are big and easy to pull out of a tank too. So you could have them in a big tank and just pluck one out every now and then to clean a little Betta tank and then put it back when it's clean.

    Sent from my SAMSUNG-SM-G890A using Tapatalk

  19. #19
    DIYFK member Meep's Avatar


    Join Date
    Oct 2013
    Location
    Planet Earth
    Posts
    3,331
    Post Thanks / Like
    Click here to enlarge Originally Posted by Nil13 Click here to enlarge
    Nerites don't reproduce in freshwater though they live there just fine. The baby snails need brackish water to survive. So there is no chance of infestation like with those damn bladder snails.
    But, they (females) do lay eggs all over the place that need to be physically removed and I don't want my tanks looking like a sesame seed bun exploded, like I said snails are not happening as RO filtered water will better suit my goals... I'm more interested in attacking the root cause not looking for a get by fix...

    So you could have them in a big tank and just pluck one out every now and then to clean a little Betta tank and then put it back when it's clean.


    I can't see it being every now and then, based on how fast the diatoms spread, it would be a full time job...

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •