DIY 6" O.D. recirc skimmer.....halp me !! :)

The Propagator

In Memoriam
I have been toying with the idea of a DIY recirc skimmer for quite some time now.
Well I finaly took the plunge!
I followed Randy Stacey's skimmer plans to an extent and added my own touches along with those borrowed form Eroreef skimmer designs.

The reaction chamber is 6" O.D. x 5 7/8" I.D. x 18" tall Extruded acrylic.
I used the same floor drain as described on Randy's site but I put my own little twist on it:


Since the floor drain was ment for 6" I.D. PVC and swallowed the 6" O.D. Acrylic I improvised and it turned out SWIMMINGLY !
What I did was place the cone ( "drain") wide mouth up on the floor and then set the tube in it.
I centered it up by rule and by hand the best I could then carefully reached inside witha fine tiped black marker while holding the tube in place with my right hand ( I'm a lefty !!)
and I marked the contact point all the weay around the diameter.

Then I removed the tube and measured 1/8th inch UP from my line. I then took my dremel and cut away a 1/8th" x 1/8th" lip for the tube to sit on over the antire radius. ( Very painstaking but SOO worth it !)

When I finished with that I test fit the tube and WOW! I got it on the 1st try! ( A few little reshapes needed here and there ofcourse but over all it came out very nice on the 1st try :) )
After I placed it on and made sure it was even I stepped back and looked at it. My 1st reaction was " DAMN THAt THING STICKS OUT AND HANGS OVER LIKE A SOAR THUMB !!" LOL!!
Soooooo....I then decided to cut the rest of the way through to remove the large over hang.

When I was finished shaping sanding and fitting I glued the cone on with weld on and made it water tight.
( Its not prety but it does the job nicely)


So then I was left with the daunting task of trying to find a cap for the bottom that I could make fit the 6" O.D. tube.
YEAH RIGHT !!! NOTHING I found in any hardware store would work . Out of shear desperation and lack of better ideas I thought "hey why not try and use what you have? The cut off part of the drain?" So i cleaned it up sanded it down a little and VIOLA !!

It fits like it was made for it! So now I had to think of a way to seal the LARGE hole in the bottom. LOL!!
EASY ! I used the drain cover as a pattern and layed it down over some 1/4" acylic sheet I had lying around and VIOLA !!
Fits like a glove !!


Again I used weldon to glue it and made it water tight.
Now I dont know if I want to make it removable or seal it up and clean it the best I can through the top ?
If I make it removable that will require ALOT more time and enginuity and I am almost out of all of that at the moment LOL!!!

So then I used the same plan Randy laid out for the removable collection cup, save for one thing. I went with the larger grey colored 2" I.D. Union. Why? Because I didnt like the whole
"solid white" Theme LOL! as it turns out this was a better idea.
Its easy to grab on to and require less force to twist on and off and seals up easier as a result.

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The Propagator

In Memoriam
So then I was left with making the collection cup.
I used the same type of cup from the same manufacturer that Randy did only I purchased two of the same cups WITH lids ;)


I had some 4" O.D. acrylic lying around from and old POS bottemless skimmer that came with a Proclear Aquatics 150 pro series wet dry so I cut a 1.5" section of it off and centered and glued ( with weld on) it on the lid of the cup.



As you can see I skipped a couple processes on you where I cut out the hole for the 2 " I.d. pvc., and where I cut down the male threaded portion of the Union.
Its prety straight forward. it dosent need to be a perfect seal because the are the cup is going to be sittin gon has a large sealing surface. I traced the pipe and used a dremel with a diamond wheel.

then I cut a length of 2" pvc glued it in place inside the Union and then layed on a nice even, thick, coat of weld-on over top of the none threaded side of the union


The Propagator

In Memoriam
Then I cut dow the male threaded portion of the unin flush with the threads and glued it in place using weld-on on to the skimmer cone.



I also scavenged a drain niple from an old collection cup and bored it out, as well as cut it dow so it would fit flush with the intirior of the collection cup when installed and glued in place using weld-on.
It accpets 7/16th O.D. x 5/6th I.D vinyl tubing.


The Propagator

In Memoriam
SO any who.....

I have 1x 1 1/4" uniseal for the return to the sump/refugium and 3 x 3/4" uniseals for the suply line from the tank, as well as for the intake and return for the recirc pump.
I aslo have and will be installing, 3 x 3/4" solvent unions to the intake and return on the pump, as well as the supply line.

This little monster has a 6" O.D. x 5 7/8" I.D. x 18" tall reaction chamber with a 1 3/4" tall actual coned surface that funnels into a 7" section of 2" ID riser tube into the 5 1/8"" tall x 5" 1/8th" wide collection cup Actual hieght with lid installed is around 6" tall)
giving it an over all height of 30 1/2" inches.

Now is where the "halp me" part comes in.
What size and what brand pump should I buy for the recirc?
How should I make the venturi?
As in which method/ mod should I use?
Do I have the valve in the right spot for proper adjustment of the water level in the reaction chamber?

None of the plumbing is set and glued in place yet ( save for the 1 1/4" uniseal )and the ball valve is the only thing I could find localy.
Last but not least.....
Where would I fnd a 1 1/4" gate valve? No one has them localy :(

Thanks for your time and your help with this fellas !

Also a BIG BIG THANK YOU to Mr. Stacey for making our lives a little easier by posting such a great and easy design to freely copy !! :)
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Limestone Cowboy.
Premium Member
Nice work there, I would go after a small footprint pump that will get max air and low watts. Now the best to fit that bill JMO is the genx needlewheels. You could mesh mod it and drill out the venturi to get a little more umph, But stock i think will do nicely.
Stock the genx gx 2400 needlewheel would fit on there and do a good job IMO.
Plus its a great price too! They sell both non and w/nnedlewheel the needlewheels are towards the bottom. Plus it should come with a venturi. :)

The Propagator

In Memoriam
Thank you for the reply's and the compliment ! :)
( Lets just hope it dosent just look "purty" and it actualy functions LOL!)

Can the Genx2400 be ran externaly?

I know the octo pumps can but will the 2000 modle be enough ?
I could probably get an octo pump wholesale from a friend of mine too. :) Do they come with a venturi?


Limestone Cowboy.
Premium Member
Sorry i had it spelled the right way first, But i changed it because josh had ity spelled that way and i second guessed myself. LOL
I dunno for sure but i believe the gen ex can be ran externally.
I have the 1000 and don't why i could not run it out of water.
I am not a fan of the octo's. Get a ocean runner if you want the better copy of the ehiem.


Limestone Cowboy.
Premium Member
Not that they are bad, They just are a lesser/cheaper copy of the ehiem, The OR is a much better pump if you want to go that way. It can pump more air and at higher head pressures.


New member

I run mine on a slightly smaller reaction chamber and it is actually too much air. I have to turn it back a bit. Also, you have to keep in mind that on a recirc skimmer the lack of head pressure means that you can use a slightly smaller pump than you normally would. With a 2" neck, I would go no larger than the OTP2000.
I didn't even do all the mods I could to this pump, and I am certain I could squeeze out at least another 5 scfh.


New member
The Propagator:
You can definitely run the GenX externally. I use a GenX as a return pump on my wifes' smaller tank. I have a GenX-1500 on my little 4" recirc skimmer. I would have tried out the OTP for that skimmer, but it wouldn't accept NPT threads.

I FINALLY ordered an air meter :) so I’ll be able to actually test the mesh mod and play with the DIY venturis on my pumps. I’m sure there will be some changes will have to be made unless it was just ‘dumb luck’ and I got it right without an air meter. That’s unlikely, but we’ll see.

I like that cup too … how well does the lid seal to the cup itself? Does it just easily slide over the cup or does it squeeze over the cup firmly at all? I don’t know if you’ve done this yet, but you’ll need some vent holes in your lid.

The Propagator

In Memoriam

Waz app baby !!!! :)

The cup lid fits pefectly and fairly tight. Its not very easy to get off if you slide it all the way on I can tell ya that LOL!
I havent tested it to see if its air tight. I doubt it is. BUT that deflector ring I put on the lid removes that problem all together.

I was about to make a vent in the cup lid tonight acutaly.
How large should I go with th event? 1 x 1/4" hole maybe ?

I think I will order the GenX 2400 needle wheel then for my skimmer. The OTP sounds like a great pump but I completely forgot about head hieght thing and the lack of giving me the ablility to run a smaller pump.
BUT if I did a mesh mod on the pump would the GenX 2400 still move enough water to suck in enough air?


New member
The reason I asked about your lid is because my lid just sits over the top of my cup and isn't tight at all. I have 4 holes in my lid. I don't recall how big they are, but you just want the air that the skimmer inducts to be able to escape without pushing off the lid or pushing down your water level ... whichever happens first.

Well I'm sure you could use the 2400 on this skimmer ... I just have no idea how much air it will pull for you until I get my air meter. I'll be doing some tests with my skimmer to get it running as well as it can and list the readings I get. After that I'll be switching it over to a recirc skimmer using the same pump. If I still feel froggy I'll probably try out the OTP 2000 and see which works better.

As for the mesh ... it can ONLY help and you would definitely be pulling more than the stock NW. I can tell you that without a meter to prove it. I had to lower my water level considerably once I slapped on the mesh. I'm sure you'll loose some flow as a result, but that's just an excellent trade off when your pulling more air than any needle wheel impeller. As long as you're getting a ton of air then you don't need flow, in a way flow/turbulence can work against you.

Oh by the way ... the OTP pump I mentioned in my earlier post was the small OTP 1000. All the larger OTP pumps accept standard pipe fittings, just not the 1000.