Algae Scrubber Flow Distributor System: Alternative to the Slot Pipe

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:





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!