Skimmer Terminology

lakee911

lakee911

New member
I'm confused about the differences between a venturi type skimmer and a needlewheel type....

Does a needlewheel only recirculate the bubbles in the skimmer?
How does the influent get in the skimmer? Another pump?

The venturi pumps water and bubbles into the skimmer, no?

Thanks,
Jason
 
A venturi pulls air into the skimmer. If the venturi is before the pump, then the pump impeller chops the bubbles up before sending them into the skimmer body. If the venturi comes after the pump, then the bubbles size is determined by the venturi itself (not at all ideal, but used on some smaller skimmers).

Air can be pumped into the input side of the skimmer if the venturi does not provide enough.

The skimmer can be fed by the same pump that processes the air. The skimmer can also be fed by a feed pump and use a recircultating pump to process the air.

Bean
 
Hey Bean, Thanks!

I want to DIY my next skimmer. I think I want to use PVC. My current AquaC skimmer is just horrible, and it has to go.

I want to gravity feed it from my tank overflow and then dump it into my sump. I won't need a feed pump. So, how should I get air into my skimmer? Recirc needlwheel (how does it get air?) or venturi?

Thx
Jason
 
You will use a recirc pump. You can either feed it by venturi or force feed air to it. The effectiveness of the venturi will depend on the size of the pump, the type of venturi, the type of needlewheel, the height of the water in the skimmer... etc etc.

You may want to spend some time reading the long DIY skimmer threads.
 
I've been trying to read what I can get my hands on.

Unfortunately, I've not been able to find a good thread of what I'd like to build. I'm not sure if I want to do 6" or 4" PVC. I'm going to run it external, so it'll have to sit on the floor.

The best thing that I've found so far is RandyStacyE's design here: http://randystacye.com/diy_needle_wheel_skimmer.htm It's just so little though.... :(
 
my skimmer is a 6" PVC recirc that is maybe 6' Tall. It is fed by an MJ606 from my overflow and returns to the overflow. I am using an Ocean Runner 3700 NW unmodified.
 
I built my skimmer from RandyStacyE's plans, and it rocks. However I am using a Gen-X 4100 as a recirculating pump. I am using the stock venturi that came with the pump, and I modded the impeller with a mesh. I do plan to do some experimenting with the venturi soon.

John
 
I think I'm going to loosely follow those plans too. Did you build the 6" diameter version? Can you post a pic? Are you gravity feeding or pumping the influent to the skimmer? I'd like to gravity feed the influent and effluent to mine. Only one pump would be used and that's for the recirc.

I found a good collection cup in the kitchen last night. It's full of flour though, so I'll have to get a new one. They're very sturdy and should be able to be drilled and tapped for an auto waste container. http://www.bedbathandbeyond.com/product.asp?order_num=-1&SKU=13572526&RN=204 I probably going to use the 7 1/2" tall container by 5" diameter container. It might look a little corny, but it'll do.

I just need to get an acrylic tube for the skimmer neck that will fit in a 2" PVC fitting. I'm not sure which size that is though.

Thanks,
Jason
 
I will shoot some photos tonight and post them to this thread.

I am feeding mine off the sump return at about 200 GPH. I tried the direct feed off the overflows, but it was way to much water flow. I used 2 inch clear PVC that I got on EBay. For my collection cup I used a 2 inch to 4 inch reducer with a section of 4 inch OD acrylic. The cup is rather small, but I have it plumbed for a collection jug. I have seen several people use the container you posted the link for and it looks like it would be more cost effective than mine.

John
 
Bean, you dont think a OR3700 on a 6" diameter skimmer is too much? I was considering the same at one point but thought I might need an 8" diameter at least for this pump... even at 6' tall (I was considering 48-54" tall myself). Not questioning it, just looking for an opinion. Sorry for the sidetrack.
 
If you have room do the 6" skimmer. I like those cups you found, I’ll check those out.

Just this morning I started a thread on a 4" version I’m making. It's for my wifes 38 gal tank with a sump. http://www.reefcentral.com/forums/showthread.php?s=&threadid=1056915

The 6" one does do a good job, I'm totally satisfied. It sits under a 55 gal in the sump. I will definitely build a bigger one when I consolidate all my tanks into one. I was thinking about going with a larger diameter, but maybe taller would be the way to go.
 
Oh, by the way that 6" skimmer doesn't have hardly ANY room between the collection cup lid and the underside of the display tank … maybe just a 1/8” gap. Thank god for the union, the collection cup can easily be slid sideways to remove it.

It's about as big of a skimmer that I could fit in the sump. It's possible that an 8" reaction chamber would have fit, but that's a totally different design.
 
I'm trying to locate some SCH40 6" 5ft length PVC. Places around here want $40 for 10ft, that is if they don't sell 20ft minimum! :(

I'm thinking of using a 6" flange on the bottom end for stability. It is $30 for one that size and I still have to plug up the bottom. It'll be sitting on carpet, for now, so it needs more stability. Wouldn't want it falling if it got bumped, etc. What'd you all do?

Thx!!!
 
if all you want is something clear, but you are going to be using PVC anyways for all of the fittings, why not just use clear PVC pipe that comes in 6"? then you can weld your PVC right to the body w/o uni-seals or bulkheads.
 
Well, I priced that out, hah and it was like $120! I can't afford to mess up a $120 stick of PVC. I'm gonna build a cheap-o version first and if all is well, then go clear. I actually did find the pipe at bLowes too! $19.38/ea.

I thought I found a GREAT base too. It's an 8" square NDS Drain Grate that's supposed to fit 6" PVC....probabably sch10 or something though. It was too small on my Sch 40 and too big on a coupling fitting. :( http://www.ndspro.com/products/Info.aspx?cat=79&class=Drainage&tab=Overview# It would probably work if I loaded it up with lots and lots of PVC glue. Not the route I'd like to go if I can help it. Besides, I'd still have to plug up the pipe somehow too.

bLowes only carried Sch80 unions, so I'll have to run over to Savko and see what they got there. That was one big honkin' union. Hopefully Savko has something a little flimsier. Heh

Lastly, I was gonna hit up Bed Bath and Beyond, but decided not to tonight. When I got home, a 20% off coupon in the mail. :) I'll get my containers tomorrow I guess.

Just need to order me a nw pump....
 
I don't know why they only had SCH80--it was available in White or Black. The white ones were in the Sch40 box. Upon closer inspection, all of my unions on the tank are Sch80! Doh! (So tha'ts where the restriction are). I WANT SCH40, so I'll check Savko.

Can't find any cheapo 2" Clear PVC so I'll get a five foot stick from Savko too. $30 for 5ft, no shipping charges.

Jason
 
I'm thinking of using a Gen-X 4100 NW pump. The reaction chamber will be 36" tall and 6" diameter PVC. Too big? Too small? Will this pump be noisy?

Thx
Jason
 
OK This my skimmer.

Full skimmer shot.
132391981-L-1.jpg


Collection cup with fitting for drain. Fitting on top is the inlet to the venturi feed.
132391926-L-1.jpg


I am using a gate valve to control the water height in the skimmer. I found it much easier to fine tune than the design Randy has on his DIY page.
132391960-L-1.jpg


Trimmed down GenX 4100 (so it would fit in my sump).
132391942-L-1.jpg


Inside skimmer.
132392000-L.jpg


return line has 2 45's and they are pointed slightly down.
132391890-L.jpg


Thus far it has only run on my mock up 100g, but I am in the process of doing all the finish work to the stand and canopy.

Check out my canopy...
http://reefcentral.com/forums/showthread.php?s=&threadid=1055695

John
 
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