Flow Options

cbaum86

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I'm planning a new setup and considering plumbing options for cabinet layout. I'm going to have the CO2 running through a reactor using a dedicated pump but I'm not sure which of the following options would be best or if indeed it matters to much.
  1. CO2 flow perpendicular to water flow with outputs on the same side.
  2. CO2 flow perpendicular to water flow with outputs on the opposite sides.
  3. CO2 flow parallel to water flow.
My initial thought is option 1 as this most closely mimics the setup with a diffuser opposite the output allowing the co2 to be dragged into the flow.

I know this will depend somewhat on hardscape and planting and may have to change once things grow in.

Thanks,
Chris
 

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Iain Sutherland

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Hi chris,

Your best option would be none of the above
Generally with two outlets the best option is positioning outlets at opposite ends, one front and one rear to create a vaguely circular flow around the tank. Often with the front outlet being positioned a few inches away from the front glass, sometimes more.
Unfortunately water in flow doesnt follow consistent patterns like in your drawings, it's a lot more irregular and as you you mention is very much hardscape dependent.

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cbaum86

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positioning outlets at opposite ends, one front and one rear to create a vaguely circular flow around the tank
I have no idea why I didn't show that when I've seen it so many times :shh: I suppose it's similar to option 3 but with one of them flipped, yeah that's my excuse!

My only concern with having an outflow across the back was it blasting across the stems that are likely to be there. I suppose that until the hardscape and plant choices are there it makes 'guessing' what the flow will do an almost fruitless exercise.

Unfortunately water in flow doesnt follow consistent patterns like in your drawings, it's a lot more irregular and as you you mention is very much hardscape dependent.
Yeah, I guess this can be seen only 2 well in existing tank with CO2 bubbles but I had to draw something without it looking like I coloured in the style of a 2 year old.
 

Zeus.

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I use option 2 in my 500l. Have maxspect gyres doing the flow and an FX6 with twin CO2 reactors going the same way. Had to use option 2 as its a room divider so only had the narrow side to get all the plumbing in.

Nice thing about the gyres is you can control their output via a schedule
 
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Your flow is far more 3d than you imagine, If you forget your secondary flow to start with and just think about what's happing with your primary flow, most of the water in the tank should be moving.
also, most of the water doesn't go through the filter, just gets dragged along with the other water.

In 2d you can work out what direction the water is spinning (blue arrows) the 3d path is harder to work out (red arrow)
if you imagine 3 spinning vortexs where would a co2 bubble get dragged..

When you add a secondary flow you want it to speed up this circulation path, you can see in the example I scribbled on that the secondary flow will be slowing down your primary flow which is the last thing you want to do.
3d.JPG
 

cbaum86

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Your flow is far more 3d than you imagine
Yes, of course. I suppose it was an oversight due to trying to explain my thoughts in a simple way when it clearly isn't.

In 2d you can work out what direction the water is spinning (blue arrows) the 3d path is harder to work out (red arrow)
When you add a secondary flow you want it to speed up this circulation path, you can see in the example I scribbled on that the secondary flow will be slowing down your primary flow which is the last thing you want to do.
Thank you, that actually makes a lot of sense and - if I understand correctly - point towards Iain's suggestion.
 
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Thank you, that actually makes a lot of sense and - if I understand correctly - point towards Iain's suggestion.
Yes, that's right, with both flows at opposite ends of the tank one front, one back.
All the rocks and plants slow things down and give you dead spots.

You could do a perpendicular flow, you would just need to put your primary flow at the back to spin the water clockwise (top view)

All depends where your tall plants are and where you can hide the pipework.
 
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