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Flow.....

krazypara3165

krazypara3165

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Joined
23 Aug 2012
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591
Location
Warrington, Cheshire
The general consensus on this forum after co2 seems to centralise around flow. Ive been doing a lot of research and if the tank has the correct filtration I cannot see how the flow can not reach most areas of the tank. Another thing that made me ponder is that the amazing tanks I have seen In person dont seem to have that much flow. The planted tanks at TGM for example are thousands of liters and are only filtered by a cannister! Just curious to hear opinions?
 
Hiya mate. Good point but when you think about it with places such as the green machine and ada for example who seem to use minimal flow, they do maintenance on their tanks pretty much every day unlike most of us.
The flow isnt just for getting the co2 round sufficiently its also for preventing dirt etc from settling on leaf surfaces etc which would prevent nutrient absorption along with co2 uptake I think. So if your doing water changes or maintenance every day almost I dont think it becomes too much of an issue.

I could be totally wrong though
 
Co2 and flow is critical in my first 30l scape I had algae problems that was down to poor flow in areas of the tank even though im running a 1000lph filter, now on my second scape ive sorted theres issues out and all is good so far,

Its been discussed before about how these display tanks run near perfectly with little flow and what I gathered is that they get away with it as they do more wc more often and are pretty much always on hand to trim a leaf wipe a smear of the glass etc so any issue that does occur is very often jumped on instantly
 
Hi all,
I think a lot of it is going to depend upon the tank dimensions, wide and shallow is great for low-tech. because you have a large "surface area to volume" ratio for gas exchange. Even with fairly minimal water turn-over gases are going to equilibrate with atmospheric levels fairly efficiently. This means that when the plants are photosynthesising C02 will diffuse in and out-side of the photo-period oxygen levels will remain at or near equilibrium with

The same applies to filters, "wet and dry" trickle filters these offer advantages for low tech. tanks for the same reason.

When you start adding CO2 the problem is reversed, rather than having a greater level of atmospheric CO2, you have more dissolved CO2 in the water and the larger your gas exchange surface is, the more CO2 you will out-gas.

One thing high laminar flow will give you is a longer residence time in the water column, and more opportunity for that dissolved CO2 to be "captured" (should really be "diffuse in through the stomata along a concentration gradient") by the plants, before your dissolved/micro-bubble CO2 is lost to the atmosphere.

cheers Darrel
 
I think that there are probably lots of reasons why high flow works well, some we're probably not always aware of, although I guess high flow isn't perhaps that necessary if you really know what you're doing.
For instance, I reckon in the case of a fuel injected tank it's something of a catchall, in that it kinda ensures against inadequate distribution preventing dead spots and it gives more wiggle room if other parameters ain't that well balanced.
This probably has something to do with reducing the thickness of the unstirred layers of water bathing aquatic plant leaves - which is a major factor limiting the diffusion/absorption of CO2 and nutrients.
I think for this reason it could also be argued that good flow is just as beneficial in a low-energy tank as it is in a high-energy set up, if not more so due to lower water column CO2 saturation.
Similarly, good flow drives CO2 and nutrients in to the substrate where they can also be taken up by plant roots, again with the potential to greatly increase photosynthesis.
 
dw1305 said:
One thing high laminar flow will give you is a longer residence time in the water column, and more opportunity for that dissolved CO2 to be "captured" (should really be "diffuse in through the stomata along a concentration gradient") by the plants, before your dissolved/micro-bubble CO2 is lost to the atmosphere.

cheers Darrel
Click to expand...

I wonder if its worth creating laminar flow in a filter. For example to put small straws inside the filter tubing to create highly directional molecules? Off topic just Darrel piqued my interest as usual.
 
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