Algae Scrubber Flow Distributor System: Alternative to the Slot Pipe

Turbo's Aquatics

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The "Slot Pipe" is one of the key components of an Algae Scrubber. The purpose is to create a thin, laminar sheet of water flow across both sides of the growth substrate, typically the #7 Plastic Canvas (knitting canvas).

The problem is, it's kind of tricky to get a nice and straight cut in a piece of PVC pipe, especially if you're not a DIY person. Even if you manage to pull it off fantastically, it tends to close up over time. Schedule 80 pipe is better than Schedule 40, but it still will close up over time in the center (the longer the slot, the more the closure).

Then, there is the issue of rotation - a slight turn of the pipe and now your screen isn't nice and centered, meaning, more flow on one side and potentially zero flow on the other.

Growth at the slot/screen junction generally can cause some spotty blockage, which increases the pressure at other areas - and this can lead to spray or "streamers" (which led to my development of the Light & Spray Blockers)

This all seems like stuff that should be pretty easy to account for. Generally, it can be. But that can end up requiring fiddling and if you're not one for fiddling, then it turns into an annoyance, which can turn into removing the scrubber.

After a few brainstorms, I think I've come up with a solution.

My idea takes the "spray bar" idea and combines it with a re-imagined version of my Light & Spray Blocker to create a Flow Distributor System that I am hoping will solve all of these issue.

The Spray Bar itself is not a new idea - many Algae Scrubber DIYers have done this, and even some commercial type units. Most involve drilling holes in a pipe and having the water spray (in streams) directly on to the plastic canvas, usually one on each side, but I've seen other techniques also. However, it always bothered me that these exposed streams would tend to create a lot of splatter, and would not necessarily create a nice even flow like the Slot Pipe did.

What I came up with is a set of parts that re-directs the water that flows out of the holes of a Spray Bar into a laminar sheet, while also blocking light and eliminating any spray issues. There is also a built-in (but not intentionally designed) bypass path, though I'm not sure it would ever kick in.

Everything is designed to snap on to any 3/4" PVC pipe and it can be fit to just about any length of pipe.

Having prototype parts 3D printed so I can verify that it works like planned...

But what good is all of that description without pictures? Worthless. So, pictures!

Here is what it will probably look like:



There will be a pair of end caps





A couple pairs of Screen Clasps that would "grab" the screen at each end, helping to keep it straight:



Top down view of a pair of them


and these would slide into a gap on the End Cap





To help keep the screen aligned (might be an issue with longer screen widths) there will also be an alignment clip



Which would line up with a notch in the screen...but I need to monkey with this once I have parts in hand.

The main part that makes this all function is the actual Light Blocker & Flow Director panel:



 
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Turbo's Aquatics

Turbo's Aquatics

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When you snap these into place...



...it looks like this (pipe removed)





Closer on the inside, you can see that a "pseudo-slot" is created by the 2 panels, and the panels are held in place on the ends and in the middle



The screen is not directly attached to the pipe, but is held in place directly under it.



On the underside, the panels block the light to the pseudo-slot



Now for the Spray Bar part - I didn't model these in, so you have to use your imagination here



No? Let me help you with that



Basically, you can drill holes pretty much anywhere you like on the lower quarter to lower third of the pipe. I have to experiment with hole size and placement, but my guess is there will be a ton of room for error here.

The Flow Distributor System allows for a "pool" to form between the Spray Bar and the Flow Distributor panels, and this pool is not really under pressure like the flow that is coming out of a Slot Pipe. At least, that's the idea. Here's the area that the Spray Bar would "inject" into.



This may also solve the issue referred to as "arcing", which is what happens when you push a lot of flow through a Slot Pipe.

Since the screen is not directly connected to the pipe at all, that means no zip ties, no rotatable ring, no inset-clasps - nothing on the pipe at all.

If for any reason your pipe gets rotated a bit (like when tightening down a union fitting or adjusting the position of a pump, etc) this will not likely affect the distribution of the flow between the two sides of the screen.

The Light Blocking portion of the panels prevents growth at the pseudo-slot, but even if they aren't 100% successful at that, the water in the pool can escape via the opening in the top edge of the panel, allowing that water to flow back down over the screen.

The only thing left to troubleshoot here is the creep factor. I'm not talking about that guy in the white-panel van around the corner, I'm talking about water that might escape the end cap and flow along the bottom edge of the slot pipe. Now, that's creepy....

If successful, this will be available as a kit for DIYers and might also get incorporated into my products...we'll see soon enough!
 

TaylorPilot

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Your square slot pipes work well and I think would be very difficult to crimp off in the middle. The two advantages I see to this design is that it would allow you to adjust the width of the "slot" just by changing out the two side pieces. Also the ability to be a good DIY solutions that can be cut to any length. Only issue I see is that if the slot began to clog, you may have it overflow the top of the pipe. If the system isn't designed to anticipate this, you may be spillage or splashing. Either way, cool idea. I'm sure in a few months you'll be on Rev 3! LOL Always improving and advancing!
 
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Turbo's Aquatics

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I think would be very difficult to crimp off in the middle
Are you referring to the center support piece?

Only issue I see is that if the slot began to clog, you may have it overflow the top of the pipe.
If you mean, the pseudo-slot clogging, that is actually the unintentional idea behind the gap between the blocker panel and the pipe - water has a path out of that assembly, but then it still gravity-falls down across the algae screen (and should still be contained between the end caps)

If you mean when the scrubber is fed directly via overflow, yes that would be something to consider. But it is with a slot pipe design also.

The whole need for a bypass path when direct-feeding a slot pipe design might actually go away with this version. The spray bar design is basically a bunch of little drains, so if a few of them get clogged, no big deal - the rest are still flowing, the pool is still there, and there is no need for head pressure to be maintained in order to prevent algae from clogging the slot (as there is in a slot pipe system that has no light blocker, that is).

You could just take the far end of the pipe and turn it up and then put a double-elbow down for post "distributor" bypass actually, since the screen is not inserted into the slot pipe, there's nothing for anything to snag on (like if an anemone goes through the drain)
 

TaylorPilot

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I just meant that the slot pipe I have on mine (Rev 4 L2) looks so rigid, that I can't ever see the slot closing off in the middle from bending.

Yea, the way it is setup, if the flow wasn't too high, the water would stick to the outside surface and transition directly to the algae screen. I still think the coolest part about this is that you can do it as a DIY solution. Just order by the foot and cut to size. Really cool idea.
 
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I just meant that the slot pipe I have on mine (Rev 4 L2) looks so rigid, that I can't ever see the slot closing off in the middle from bending.
Yup, that was the idea behind the Square Pipe, but that is pretty specific to my scrubbers. This design should actually work with my scrubbers also. That was intentional...:)
 

fab

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Will you make this new design be a straightforward upgrade to rev 4 units? ... Without any DIY side projects required by us users? ... Some kind of snap-in replacement of some parts?
 
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That would probably be pretty easy to do. Will know better once I have parts in hand to play with
 

fab

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How long do you think it might be before you have this new design figures out? Days, weeks or months?
And will you be aiming to make it a simple upgrade for the rev 4 units?
 
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I'm getting the 3D printed parts probably next week so I can play with them and see if my idea actually works the way I envisioned. There will likely be a few revisions and tweaks, but I think the core of the idea is pretty solid, it's more about exactly how it's implemented. I would say maybe a week or two to lock in the design, depending on turnaround of 3D printed prototype parts and shipping. Steve's LEDs is doing the prototyping, they have an excellent 3D printer (they make the potentiometer enclosures for me).

After that is all locked in, I'm looking at a few days to get the models done, and then I have to get in line for mold production and first article approval, which can take months...at this point I would be shooting for the end of September for a product release I think.

As far as backward-compatibility to my scrubbers, it should work. My screens are shaped so that the section at the top that is inserted into the slot pipe is 2 rows narrower than the "active area" of the screen, meaning, one should be able to just slice that area off and clamp the screen at the 2 corners and attach it to a spray bar.

DIYing the spray bar should be pretty straight forward, what I need to experiment with is the hole size, number and spacing of holes, flow rates, head pressures related to number/size/spacing of holes, things like that. I'm pretty sure others have done this but might not have gone to a great extent to determine what is the most optimal, and to my knowledge, no one has attempted to make a spray bar work in conjunction with a flow director in the manner I am thinking. Once I have that figured out, it should be as simple as selecting a nice straight piece of pipe, cutting it to length, drilling the holes, and capping it. Which I can do pretty easily, if anyone needs me to - that takes a lot less setup than cutting a slot pipe with a router & jig.

There may be some factors I am not considering, and there are some things that are difficult to anticipate, like how the flow and/or pressure might cause the flow director to bend outward, etc. That particular aspect is why I combined the light blocker with the flow director, it serves a dual purpose - the obvious, plus it acts as a cross-brace of sort to help maintain the shape of the flow director. The center support is there in case that might not be enough, but adding a perpendicular component (a horizontal "wing" or "tab") might serve that purpose also, at least for short spans like 6" or so. I would think that anything longer than that would probably require a centerpiece to keep the flow directors from bowing outward slightly, and even though that might not seem like a big deal, it is - a difference in the spacing between the tips of the flow director and the screen of 1/16" in the middle (wider in the middle) potentially could mean a 50% flow difference in that area, which would completely defeat the purpose and be akin to a slot pipe that is wider in the middle than the ends.
 

fab

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If this design works out well to your satisfaction as a real improvement then I would like to have it in the unit I have in your queue.
Good luck with this project!
 
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It got put on the back burner, the parts were great but need to tweak it or re-think it. I think it still has great potential but when there are too many irons in the fire, gotta take a few out for a bit
 

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