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Co2 Distribution and flow pattern with diagrams

Discussion in 'CO2 Enrichment' started by samh, Nov 8, 2011.

  1. samh

    samh Guru Class Expert

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    Hey Guys,

    I think i've discovered what might be giving me inconsistent co2 distribution/saturation?.. well just a theory anyway, any advice otherwise is always appreciated. Flow pattern...? I've been fiddling with flow patterns by moving things around increasing and decreasing 6the total flow etc...

    My judge has been pearling as it's the only thing that seems to change day to day. which i'm presuming is due to co2 fluctuation, again any advice otherwise is cool:D It was changing without me doing anything different to the point where the plants just stopped pearling, so not sure what was happening.

    So now since i can longer find the sweet spot i need help haha.

    A few tank specs
    130g / 500 Litres = 48" x 24" x 28"
    Co2 - ph controlled 2x needle wheels, 1 sera 1000 reactor
    Flow - 8400L/hr approx Is this Too much?
    Filtration 1x eheim 2217, 1x eheim 2215(soon to be replaced with a 2217) 1x 1500L canister

    I'm wanting to know where to put all this flow and simplify it. At the moment i have flow going everywhere.
    How would you guys position all the flow?

    A rough Diagram to show current flow and why i need it changed
    [​IMG]

    Full tank shot of plant layout
    [​IMG]

    [​IMG]

    Any advice or a hint on where to start would be greatly appreciated :D

    Sam
     
  2. samh

    samh Guru Class Expert

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    Also just to add the goal of this tank is to just grow a fairly wide variety of plants and learn really, what i can and can't do. When i get stuck i come here for the advice of the experts :D haha
     
  3. dutchy

    dutchy Plant Guru Team
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    Very complicated setup. I just use two 500 gph filters on a 180 with very good results.

    View attachment 2562

    LH%20vs%20RH%20just%20below%20surface%20CO2%20injection.jpg
     
  4. samh

    samh Guru Class Expert

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    Hi Dutchy,

    Yeah it is, i'm trying to simplify it. Just stuck as to what would work. Are the 500gph pumps your filters or separate?

    This is my new plan
    [​IMG]
    [​IMG]

    It only includes the eheim 2217's flow, which is similar to your pumps, still not sure where to fit the needle wheels and wavemakers. I'm 3000l/hr off my target flow... Is it possible to have too much flow?
     
  5. dutchy

    dutchy Plant Guru Team
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    I think your two Eheims are enough for your tank. Very high flow induces stress to plants which a consequence of less growth and foliage development.

    "Water movement has long been recognized as a prime factor regulating the growth and distribution of submersed aquatic macrophytes. As early as the 1920s, Butcher (1933) recognized that changes in water flow or velocity could alter the biomass and species composition of submersed aquatic macrophytes in streams
    and rivers. Physiological studies have shown that photosynthetic rates of freshwater macrophytes are positively correlated with current velocity at low levels
    (0–0.10 m s−1)"

    http://www.jlakes.org/web/Interaction-watermovement-sediment-macrophyte-H2001.pdf
    http://www.jstor.org/pss/1941754

    Now there's the boundary layer aspect where the water direct over the leaf is almost stagnant. We need to move the water to get this boundary layer moving so the plant is able to take up CO2 etc. Still there is not much flow needed to do this:
    "Laboratory experiments have generally shown positive relationships between photosynthesis or nutrient uptake and flow rates for very slow current velocities
    (≤0.01 m s−1 for freshwater species), presumably due to a greater flux of solutes resulting from reduced thickness of the diffusion boundary layer."
    http://www.jlakes.org/web/Interaction-watermovement-sediment-macrophyte-H2001.pdf

    Also:
    "The combined effects of water velocity (U) and dissolved inorganic carbon (DIC) concentration on photosynthesis rates of Vallisneria americana were investigated. The net photosynthesis rate or O2 flux (Jobs) from leaves increased with U from 0.20 6 0.01 (mean 6 standard error) mmol m22 s21 at U 5 0 m s21 (i.e., in stagnant water) to 2.1 6 0.07 mmol m22 s21 at U 5 0.066 m s21"
    http://aslo.org/lo/toc/vol_51/issue_6/2734.pdf

    Still that means that with some flow the photosynthesis rate was 10x higher, but only at 0,066 m/s.

    Madsen et al. (1993) showed that net photosynthesis of eight freshwater macrophyte species decreased as current velocity increased from 0.01 to 0.086 m s−1.
    Thus, slow currents appear to enhance the growth of freshwater macrophytes by increasing the flux of CO2 or nutrients across the diffusive boundary layer, whereas only slightly faster currents constrain growth due to mechanical stress. So flow is needed, but we don't need to overdo it.

    That said it's obvious that these figures are about average flow and that flow at the outlet point should be considerably higher. But when this high pressure flow is at the water surface, it helps with gas exchange and is considerably reduced when it reaches the plants. Also a pulsating flow could help because it makes flow patterns change continiously and prevents dead spots.
     
    #5 dutchy, Nov 9, 2011
    Last edited by a moderator: Nov 9, 2011
  6. Tom Barr

    Tom Barr Founder
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    I typically just have one side that has high flow.........

    Upper region and just low enough to cause some rippling without breaking the water's surface.

    Seems to do the best as far as results, trade offs and aesthetics.
     
  7. samh

    samh Guru Class Expert

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    Thanks guys,

    Thanks Dutchy for that info.

    this may seem like a crap thing to talk about but it's helped me a lot.

    I know the general rule for flow is 10x volume, i think i can get this with the 2 x 2217 eheims like above and then 1 x 1000 needle wheel in one corner blowing to the other corner to do a circle around the tank and maybe a little nano wavemaker if need be.

    The 2217 filters will be me surface rippling as well, is it ok to have co2 reactors hooked up to these with their outlets so close to the surface? I don't want to waste any co2
     
  8. dutchy

    dutchy Plant Guru Team
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    In my tank the outlets are 2 inch under the surface, blowing straight but because the two currents are opposite to each other the CO2 enriched water is forced down in the middle. I can see the CO2 hit the substrate.
    You don't need to use the spraybars, just the single outlet is ok. If you think you will waste CO2, point them just a few degrees downward and let the wavemaker do what's it supposed to do. make little waves ;)

    I still don't know where the 10x turnover rule comes from, to me it's a little bit like the WPG rule. Just an indication. It depends a lot about stock, hardscape, plant density and tank size. A lot of factors.

    A smaller tank needs less turnover because the high pressure area form the outlet blows straight until the other side. You don't want to stick your plants to the side window I guess. Then there's also the astethic aspect. Less hardware = more pretty. :)
     
    #8 dutchy, Nov 9, 2011
    Last edited by a moderator: Nov 9, 2011
  9. "Q"

    "Q" Prolific Poster

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    I guess I'm in disagreement with everyone else here but, I'd say the actual number (remember Biollante's signature?) of gallons of water per hour moved is much less important than the quality of the flow actually reaching the plants.

    To say the same thing in a different way: The better you distribute the flow throughout your tank the more gallons (or liters)per hour you can "put into it" before reaching the point where plants are being buffeted with a high velocity current.

    To get even more technical, we could say: The more surface area of our plants we can cover with a high quality flow the happier they will be. To that end, spray bars are an excellent way to achieve this especially near the substrate where it can be difficult, if not impossible, to mount a powerhead effectively. A mix of spray bars and a powerhead or two would probably be equally effective but, IMHO expecting a bunch of single output pumps on their own to produce a nice, distributed flow throughout the tank is not very logical.

    I'm sure there are tanks with much less than a 10x turnover that have areas with too much water flow and other tanks with 25x that have none.
     
  10. Tom Barr

    Tom Barr Founder
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    [QUOTE="Q";75503]I guess I'm in disagreement with everyone else here but, I'd say the actual number (remember Biollante's signature?) of gallons of water per hour moved is much less important than the quality of the flow actually reaching the plants.

    To say the same thing in a different way: The better you distribute the flow throughout your tank the more gallons (or liters)per hour you can "put into it" before reaching the point where plants are being buffeted with a high velocity current.

    To get even more technical, we could say: The more surface area of our plants we can cover with a high quality flow the happier they will be. To that end, spray bars are an excellent way to achieve this especially near the substrate where it can be difficult, if not impossible, to mount a powerhead effectively. A mix of spray bars and a powerhead or two would probably be equally effective but, IMHO expecting a bunch of single output pumps on their own to produce a nice, distributed flow throughout the tank is not very logical.

    I'm sure there are tanks with much less than a 10x turnover that have areas with too much water flow and other tanks with 25x that have none.[/QUOTE]

    I'd be inclined to agree with the above.
     
  11. samh

    samh Guru Class Expert

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    Thanks Dutchy,Q and Tom

    Yeah i remember reading in one of Toms posts that high flow is ok if at low pressure. I'd guess that means spray bars and wavemakers?
    I've reduced my flow considerably by removing 1 Rio 1100 NW, 1x 2000l/hr nano wavemaker, 1x 1200 l/hr pump powering a co2 reactor.

    Too much hardware was a massive thing i didn't want, which i had with no real gain in plant growth anyway. So i agree Dutchy heaps better:D

    Thanks Q that makes perfect sense, quality of flow is the key. The flow in my tank is really important as i'm trying to grow Aponogetons as well which tend to blow around with too much and shade plants. At the moment it's standing up fairly good with a very gentle sway.

    I'm thinking that with the 2 eheim 2217's which probably won't put out 1000l/hr (most likely 800ish) blowing towards each other with the spray bars should give me that pattern you displayed dutchy.

    Then across the front with low density/foregound plants a 1000l/hr NW circling around the tank. It's hard to spread their flow i found that the mist gets caught in the spray bars and you get larger bubbles. I might try again though.

    I've got the wavemakers there to fix any dead spots if they show up.

    I've definitely noticed better pearling today then the other days and tank looks heaps roomier :D

    Would 2 eheim 2217 be sufficient in a 125-130g tank ? just checking :D
     
  12. shoggoth43

    shoggoth43 Lifetime Charter Member
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    I have to wonder if one long spraybar aimed down across the back of the tank might not be one of the better methods for flow. No real "hot spots" anywhere. A simple prop pump somewhere might be added for the fish's entertainment but otherwise this might be the way to go.

    -
    S
     
  13. ShadowMac

    ShadowMac Lifetime Members
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    My experience has led me to dislike the spray bars as the small flow outlets dissipate quickly in thicker vegetation. I have liked the strong flow across the front panel towards the top just below the water surface, to avoid agitation. It then spreads down the opposite side panel down and along the back of the tank.

    In larger tanks I wonder if the same thing can be done with an outlet in the opposite corner of the other outlet. If the flow moves along the top until spreading down the other side panel it shouldn't blow down rear plants unless they grow to the surface.

    my 2 cents...
     
  14. samh

    samh Guru Class Expert

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    First guys thanks for the ideas, i had tried lots of things and this definitely seems better.

    [​IMG]

    the needle wheel blows around the tank, like what you suggested ShadowMac. I can put another needle wheel in the other corner (top left in diagram) but the other one seems to make it around pretty good atm.

    I have 2 nano 2000l/hr wavemakers which i can put under the spray bars at opposite ends to boost up a bit. The spray bars are just under the surface giving surface rippling. I'm still noticing some changes in pearling, it seems very in-consistent from day to day.
     
  15. samh

    samh Guru Class Expert

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    Hey guys,

    Just an update, pearling seems to be more stable day to day. I'm still having trouble with lower leaves of plants melting and stems. Mainly in limnophila aromatica and pogostemon stellata. I'm leaning towards light as the issue although just want to make sure? There's no downward curling leaves or deformed, twisted tips if that helps.

    Cheers
    Sam
     
  16. csmith

    csmith Guest

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    As densely planted as your tank is light could very well be the issue. However, keep in mind proper flow in a tank planted that thick will be a little difficult to obtain.
     
  17. samh

    samh Guru Class Expert

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    Yeah I'm not sure yet. I don't want to fork out more $$$ if its not a light issue. It also may be caused by me planting stems to close. I think I'll try planting stems individually. Hopefully its something simple like that. How does everyone else plant stems?

    I'm using a vertex illumilux led fixture
     
  18. dutchy

    dutchy Plant Guru Team
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    I also have Aromaticas planted dense but no lower leaf loss. But I had it for some time. The probllem seemed to disappear after a good deep substrate vacuuming, although I have absolutely NO ways to back this up.

    Now I'm very lazy with doing substrate vacuuming, so when I finally did it, there was a LOT of dirt in it. Maybe it has something to do with clogging up of the substrate. Again, it could be just correlation.

    You could try it though.
     
  19. samh

    samh Guru Class Expert

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    Yeah it's worth a try i never do substrate vaccuming either, i couldn't be bothered pulling plants to do it. I'll happily try anything. Do you plant each stem individually or in bunches?
     
  20. dutchy

    dutchy Plant Guru Team
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    I plant Aromaticas individually. Smaller stems in bunches. If it helps, pls post the result.
     
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