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Discussion Starter · #1 ·
I've been contemplating flow patterns, and I'd like thoughts/comments/ideas from others.

What I'm currently thinking about is some sort of Calflo overflow (as described by Beanimal) for the tank outflow.

My overall goal is to minimize the visual intrusion into the tank of the filtration system, to that end I envision covering the back of the tank and the front surface of the overflow box with slate or some such to minimize its visual impact.

To that end, for the inflow, I'm contemplating mounting a spraybar on the underside of the Calflo "box" aimed to send the inflow down the back of the tank. What I'm thinking is that it would set up a circular motion: down the back, across the bottom, up the front and then back across the top to the Calflo "box".

I've already realized that I'll probably have to arrange a powerhead or circulator to prevent water from simply spinning in the middle of the tank and never getting filtered/refreshed (I figure that flow diversions from the aquascaping will help some there), but I'm hoping for thoughts about other possible pitfalls with the idea.
 

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Discussion Starter · #3 ·
Good question. Partly because I think this will be less visible, and partly because I'm specifically thinking about this flow pattern, and partly because I want the overall flow to be as gentle as possible.
 

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I think the best flow pattern is a vertical spraybar in the front right corner pushing water quickly over all the low plants and rebounding back to the right rear corner where the intake can pick up the debris in the now slowed current. This seems to be the more popular patern with some of the big boys and would work great on a in wall tank that shows only 3 sides.

I use powerheads in this arrangement but it's a little modified and works good, and with a wavemaker or just by twisting the magnet of the pump you can change the flow breifly to stir up debris if needed.

Power heads or Circulation pumps with a wide flow are best and more power is better than not enough and this is where a wavemaker can be handy in a planted tank, by controlling high power with alternating surges from each pump, plus the plants look nice dancing in the current and most fish love it as well.
 

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To me the Calflo is just a modified sump overflow, which is great for surface scum but tanks with high flow and lots of oxygen in the water don't have problems with surface scum. It seems that this system would kill all the flow in your tank and is equivalant to having you intakes & exhaust behind your background, leaving no currents in the tank. I don't have a good solution but clear lily pipes on the end would be less of a distraction in a show type tank.

I still think one end of the tank burried in the wall/stand or what ever would be better.
 

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NatCh, what size tank? I think a calflo is a great idea because it pull water from a great area of the tank. Personally I don't think lily pipes cut it on large tanks.

The idea of the lily pipes is to create one big circulating loop within the tank. I think your idea will do the same sorta thing. I'm adding a closed loop to my tank cause the overflow is at one end of a 6' tank so I want to add to the circular flow.
 

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Water flow is pretty hectic when pushed, and slightly hectic when pulled, from one point.
Its impossible to create laminar flow in this manner because water pushes water out of the way, and this means it just moves off to the sides and creates vortices.

The only way to get true smooth laminar flow is if your using gravity to move all the water in an identical fashion.
An overflow is pretty good at creating laminar flow at the surface, but right below the moving layer of water is vortices, and wherever the inflow of water is from the overflow is going to have loads of vortices too.

The best thing would be to have a waterfall on the left side of the tank that runs the complete depth of the tank, and a large slit in the glass on the bottom right side and some external plumbing to keep it all going round.
You'd be filtering very efficiently since all of the water would be moving in the same direction.

It'd be pretty cool!

Of course the size of the opening on the bottom left side of the tank would dictate the flow rate, so you'd probably want a variable opening, and a mesh to keep critters out!
 

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Discussion Starter · #9 ·
I have just noticed that I did not mention that I am interested in keeping the current low, something suitable for angels or a betta. I meant to say that. I also do have a sump system in mind, for a number of reasons which aren't really relevant to this discussion.

Justin, I'm thinking 70, 75 gallons, so not huge, but not small.

I have also thought about a river type tank, such as some of you seem to be hinting at, but that would be a totally different thread. ;)
 

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I have just noticed that I did not mention that I am interested in keeping the current low, something suitable for angels or a betta. I meant to say that. I also do have a sump system in mind, for a number of reasons which aren't really relevant to this discussion.

Justin, I'm thinking 70, 75 gallons, so not huge, but not small.

I have also thought about a river type tank, such as some of you seem to be hinting at, but that would be a totally different thread. ;)
Wouldn't be so much a river as much as just the most ideal flow pattern.
It just so happens to be that the flow of a river is laminar. There isn't a jet of water pushing the rest of the river, its just gravity moving all of the water evenly.
You could have the flow be very very slow, and achieve greater effective turnover rate than with any other method.
Keep in mind that with normal filtration some of the water will go through the filter more times per hour and some of it will go through less.
With a uniform, laminar flow like I suggested you could probably get away with only filtering something like 2-3X the tank volume per hour, since for each 1x turnover of the tank water, you would be taking nearly 100 percent of the water molecules through the filter.
There would definitely be some vortices here and there but over all very efficient.

A very slow, but uniform current, much like well... almost all fish experience in the wild.
 

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Discussion Starter · #11 ·
Thank you, Chlorophile, but I'm wondering how one would go about cutting such a slit in glass?

Now that you have described the ideal flow pattern (and I agree what you describe would be ideal), I wonder if you have any thoughts on the flow pattern I was asking about?

You see, I don't expect to be able to seat either end of this notional tank into a wall, and I prefer to be able to see in the ends of the tank, anyway, so I don't really want to cover them.
 

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Cutting into the glass would be easy with the right tools, but as you said this is not practical for your application.

I think the flow you described would work, what might be better is if the spray bar was on the bottom back glass facing towards the bottom front glass, but it would be similiar and probably not much better, so I'd just put it wherever you think it will be the most hidden and best looking since you are doing this also to reduce the visual impact of equipment in the tank.
 

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Any idea how how hard it is to do the slit? I want to do a overflow at one end using the weir and an external box. I'm frankly just afraid. Drilling holes seems easy to me, but cutting a slit does not. Maybe you could spell it out for me? I'd really like to do it.

Sorry to thread hijack.
 

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Any idea how how hard it is to do the slit? I want to do a overflow at one end using the weir and an external box. I'm frankly just afraid. Drilling holes seems easy to me, but cutting a slit does not. Maybe you could spell it out for me? I'd really like to do it.

Sorry to thread hijack.
Well to be honest, I haven't done it, and it would probably be something better left to a professional...

BUT, if you were going to do it you would need some guides to keep the router steady and a router with the appropriate bit, and a friend to constantly squirt lube on it.

I bet someone could do it for you though, it just depends on who is in your area.
 

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Discussion Starter · #15 ·
Not a slot, but here's a guy that put a long notch in the back, top edge of his tank with a diamond roto-zip bit.

Frankly, I'm impressed and surprised. :smile:
 
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