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Substrate Porosity

Discussion in 'Advanced Strategies and Fertilization' started by aquabillpers, Feb 23, 2005.

  1. aquabillpers

    aquabillpers Lifetime Charter Member
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    It has been stated that one of the benefits of specialized substrates is
    that ". . . the porosity allows faster cycling of nutrients and remineralization . . ." and that " . . . porosity also enhances nutrient retention. "

    "Porous" is defined as "admitting the passage of gas or liquid through pores or interstices" and "Easily crossed or penetrated."

    From that it would seem that the larger the grain of the substrate material, the greater would be its porosity, within reason, of course. Gravel, being more porous than a clay-based substrate, would thus provide faster cycling of nutrients.

    Or am I missing something?

    Bill
     
  2. Tom Barr

    Tom Barr Founder
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    Re: Substrate Porosity

    There is a limit to it, a happy medium.
    There is a good amount that allows for a fair amount of aerobic exchange and then mainly internal anaerobic exchange.

    Regards,
    Tom Barr
     
  3. chubasco

    chubasco Guru Class Expert

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    Re: Substrate Porosity

    Actually, gravel is for the "poor us" that can't afford them fancy store-bought
    substrates :) I have a problem with the premise that gravel is more porous
    than Schultz's Clay Soil Conditioner, Turface, Flourite, etc. It is certainly heavier, more adamantine, than those materials. I soak my clay soil conditioner
    in rainwater for several days before using to ensure some of it will not float.
    I don't have to do this with gravel.....

    Per cc of clay particles to cc of gravel, which absorbs more water?

    Bill
     
  4. aquabillpers

    aquabillpers Lifetime Charter Member
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    Re: Substrate Porosity

    I definitly agree! :) But if I could find a reason that the expensive stuff is better than the poor man's substrate, I'd spring for it. (Well, probably.) Greater "porosity", which apparently brings more water column nutrients to the roots, might be one reason. But if the cheap stuff with larger particles permits greater water movement, then . . .

    I don't know. It would seem to me that if one added one cc of gravel to one container of that volume and added one cc of say, flourite or play sand, to another, and then added water to each a drop at a time, the container with the gravel would accomodate more drops before overflowing. But I don't know.


    Might that not suggest that the water has trouble penetrating the clay?




    If "porous" means letting the nutrient-containing water flow through the gravel more easily, then I'd think that 2mm - 3mm gravel would be more "porous" than, say, 1mm - 2mm gravel, and both would be more porous than a finer grained material, like sandbox sand. I know through observation that water flows very slowly if at all through modeling clay. Also, clay soils are considered to hold water better than sandy soils, which suggests that the latter are more porous.

    Bill
     
  5. chubasco

    chubasco Guru Class Expert

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    Re: Substrate Porosity

    Bill, (can I call you "Bill" :) ) it suggests to me that the pores are smaller and
    more of them, which would increase the time to absorb the water.


    Well, porous here means they act like little sponges, when all those little holes
    get filled with nutrient-enriched water. Sand being smaller particles have less pores, less sponge capacity, so water goes right on by them after they are filled. I may be all wet in this, but that's ok, I've got pores, too, lots of 'em!
    :)

    Bill Ruyle
     
  6. Ian H

    Ian H Guru Class Expert

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    Re: Substrate Porosity

    For the sake of argument can I adjudicate and say you're both right, and indeed you're both wrong also.

    Your differences are not based on a sound starting definition. Gravel for instance is a loose term. Gravel can be based in different materials. I assure you that my substrate gravel which is granite based has virtually no porosity. If it were sandstone or limestone based it would have more, and so on. Similar story for clay, some modified clays are very porous, expanded clay pebbles for instance.

    As I said you are both right and wrong. I have the potential to be the most right because I have observed the base line. :D

    Ian
     
  7. chubasco

    chubasco Guru Class Expert

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    Re: Substrate Porosity

    Gee, Ian, you're no fun at all! :)

    Bill Ruyle
     
  8. Ian H

    Ian H Guru Class Expert

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    Re: Substrate Porosity

    Sorry Bill but it could have gone on for ever.

    By the way the H in my signature stands for Hunt. You are in my town, and in fact I may own your house. So watch it. :)

    Ian
     
  9. chubasco

    chubasco Guru Class Expert

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    Re: Substrate Porosity

    Ian, thanks for euthanizing our discussion :p Actually, having been here a
    couple of years, I like the name "Huntspatch" better :rolleyes:

    I'm sure you'd make a fine landlord :D

    Bill
     
  10. Ian H

    Ian H Guru Class Expert

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    Re: Substrate Porosity

    I would make a superb landlord because I know what type of gravel to lay in your drive. :)

    Ian
     
  11. aquabillpers

    aquabillpers Lifetime Charter Member
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    Re: Substrate Porosity

    Bill and Ian,

    I just got done with a strenuous workout and I am perspiring profusely, through my porous, I assume.

    Bill
     
  12. Tom Barr

    Tom Barr Founder
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    Re: Substrate Porosity

    An increase porosity does not mean it's not dense.
    EC, MPV and ADA, Flora base etc are light weight, Flourite/onyx sand are heavy.

    MPV is cheap...........add sand(40:60/50:50 etc) to that and it's got the weight.

    These other costly substrates are useful since they are a one time expense. They last forever(onyx, EC and Flourite do anyway).
    Folks had few issues spending 300-600$ for heating cables and those did not do anything as far as plant health.

    Took me several years to show that, but they are seldom sold in many places today.

    Regards,
    Tom Barr
     
  13. chubasco

    chubasco Guru Class Expert

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    Re: Substrate Porosity


    Exactly right, there, Tom...I'm about as dense as they come and I got lotsa
    pores! :p

    Bill
     
  14. Ian H

    Ian H Guru Class Expert

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    Re: Substrate Porosity

    OK Tom I think I've just about got it sorted and you throw another gravel on the drive. What the heck is MPV...................Never come across that one.

    I get your point about the one time expense, if going through the hassle and cost of changing to EC or even MPV, then as long as there is a decent chance that I will obtain positive,long term benefit I'll do it.

    I still am feeling that EC is my best route. How about if I add black sand to the EC, would it add weight to enable me to plant securely? Also would it, in time, sift to the lower layers?

    Ian
     
  15. Tom Barr

    Tom Barr Founder
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    Re: Substrate Porosity

    "Orifices" would be the correct term unless you are a dematologist, in which case flourite makes an excellent skin ex foliator.

    Regards,
    Tom Barr
     
  16. Tom Barr

    Tom Barr Founder
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    Re: Substrate Porosity

    Same thing as Prolfile but 5-10x cheaper.
    If you played baseball instead of cricket, you'd be familar with it.
    They put it on baseball diamonds.

    To some degree it will sort out, but if you uproot every so often and rearrange things, then it's less of an issues.

    EC is inconsistent in sizing and yes, the biggest lightest piece will move to the top.

    If it were reversed, I'd like it a lot more.

    Regards,
    Tom Barr
     
  17. chubasco

    chubasco Guru Class Expert

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    Re: Substrate Porosity

    MPV stands for multi-purpose vehicle (Mazda). And for your substrate, EC
    does it, okay there, Thread Slayer? Thankyougoodnite, :D

    Bill
     
  18. Ian H

    Ian H Guru Class Expert

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    Re: Substrate Porosity

    You're just being a silly billy now. :)

    Ian
     
  19. chubasco

    chubasco Guru Class Expert

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    Re: Substrate Porosity

    Ummm, perhaps....when you get the EC, have a grownup post pics of your setups, thanks. :p

    Bill
     
  20. Ian H

    Ian H Guru Class Expert

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    Re: Substrate Porosity

    Will post as requested but it will take some time to afford the EC on the proceeds of my paper delivery round. Then I've got to buy the camera , then find a grown up. By then this forum may allow direct attachments to be posted.

    You seam to be the second person I've upset using the term silly on this forum. Does silly mean something more severely critical in the States than the UK?

    I must stop saying silly.I must stop saying silly.I must stop saying silly.I must stop saying silly.I must stop saying silly.I must stop saying silly.I must stop saying silly.I must stop saying silly.I must stop saying silly.I must stop saying silly. :)

    Ian
     
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