Recirc pump placement

[MMM33732]

The body of the skimmer I'll be making will be 4" diameter x 38" tall. It will be recirculating style most likely gravity fed. Now how do you know where the best place to tap in for the recirc inlet and outlet is? I read the higher the better, but if the recirc pump is the only thing making bubbles, you wouldn't want it too high. Since the body is about 3 feet tall, I was thinking the pump inlet should be about 9" up from the bottom and the pump outlet about 12" up from the base. That would leave at least 2 feet of body for the bubbles to be in. Any advise or thoughts from the pros out there? Also, whats a better design for where the recirc pump plumbs back into the body, the octo style were its a "T" and directs bubbles to the outside portions of the skimmer body, or a 45 degree angle and a slight downward/side angle so its creates a swirling effect? Also, I could make the body 4' tall instead of 3 if the added foot in length would do a good amount more..

[pescadero]

i'm working on a 6-inch gravity fed skimmer. maybe i can help. i had originally planned on a 4-5 foot tall reaction chamber, so that i could get a 3-4 foot bubble path length. that kind of height requires a serious pump, and the garden variety low pressure high flow pump that many DIYers choose for shorter skimmers won't be suitable for the job.

much of this will depend upon the capabilities of your pump/venturi combination. as the height of your water column increases, the amount of head that your pump/venturi has to work against will increase. increasing the head height will decrease the amount of air volume that the venturi pulls and the amount of bubbles that your skimmer will produce.

it would really help to know more about your pump/venturi combination before determining where to put the holes.

if you want to do some experimentation in this regard, its easy enough to locate the plumbing at the bottom of your skimmer and test the skimmer's performance at different water column heights. depending upon your choice of pump/venturi, you may end up needing to shorten your skimmer height.

[MMM33732]

I planned to use a Rio 12hf I have that I'm not using anymore. It supplies 750gph @ 1ft and 630gph @ 4ft with a max head of 9.5ft. With 2ft of water above the pump, that should be roughly 710gph minus some for the fittings and venturi restriction. I would assume that that would be able to provide plenty of suction for the bubbles for a 4" wide body, but I'm certainly no expect.

[pescadero]

my limited experience with this tells me that unless you're doing a carbon-copy of what somebody else has already done, its pretty hard to predict performance.

i was using a Quiet One 3000 pump, which is rated at 780 gph up to a max head of 10 feet. Realistically, that means 780gph at 0 feet and 0 gph at 10 feet. With my venturi its probably good for a 2 foot bubble path, nothing more. it won't handle a 5-foot tall skimmer body with a 3-4 foot head. no way.

for a taller skimmer you need a pump that can handle the pressure head. that is, unless you were to use forced air injection. we've been talking about that in my thread on pump selection for a 6-inch skimmer.

I think if you build one of the "Randy" style skimmers that's got a fairly short body, that pump should work out great.

[pescadero]

just to keep things in perspective, my comments are referenced to a pump using the stock impeller that has not had the mesh mod performed on it.

[MMM33732]

So does the placement sound good then?

[pescadero]

i think that the consensus of opinion around here is that if you're going to build a skimmer, you need to design it around your pump. you need to know the pump;s performance data to determine where to place the recirc fittings and/or how much head height to use in the skimmer. essentially, if you don't have good performance data on your pump, you're going to have to generate it to answer your question.

unfortunately, building a skimmer involves a lot of R&D expense. unless you carbon copy the design of an existing unit, you're building a unique prototype. no mater how hard you try, there's always going to be a mistake along the way, and/or a design change that sends you "back to the drawing board."

my personal recommendation would be to mount everything as low as is physically possible, and if you find that your pump can't handle the head, then you have two options: force feed air, or cut the column shorter. doing it that way, at least you won't run into mistakes that trash your skimmer body.

hth.

[MeuserReef]

Pescadero,

When mesh-modding the QO3000, do you start with the NW version impeller or the stock impeller? I dont want to pay for something that I wont end up using.

[MMM33732]

Also, whats better for the recirc input, a T like Octo uses or a 45 degree at a slight downward angle to create a swirling effect?

[pescadero]

Originally posted by MeuserReef
Pescadero,

When mesh-modding the QO3000, do you start with the NW version impeller or the stock impeller? I dont want to pay for something that I wont end up using.

I'm no QO3000 modding expert by any stretch of the imagination. But everyone starts with the standard 3-bladed impeller, and cuts off the 3 vanes so that only a flat disc remains. there's a quiet one modifications thread that covers it in detail.. google this site for "quiet master" and you'll find it.

[pescadero]

Originally posted by MMM33732
Also, whats better for the recirc input, a T like Octo uses or a 45 degree at a slight downward angle to create a swirling effect?

i think that all of the actual mixing takes place in the volute. locate your air intake as close as possible and let the mesh mod do the work for you. beyond that, i don't think that the plumbing isn't too important as long as you maintain free flow.

[MMM33732]

One would cause more turbulence while one would creat a swirling action. Which is better?

[pescadero]

i don't think it matters.

[kinghokus420]

i have mine swirling with mesh on a sedra 3500 and it works very well.

[MeuserReef]

Originally posted by pescadero
I'm no QO3000 modding expert by any stretch of the imagination. But everyone starts with the standard 3-bladed impeller, and cuts off the 3 vanes so that only a flat disc remains. there's a quiet one modifications thread that covers it in detail.. google this site for "quiet master" and you'll find it.

Thanks. Heres the link for others that may be interested

http://archive.reefcentral.com/forum...readid=1170073

[alpine]

Just so everybody knows.The whole swirling thing has been already proven here on rc by the skimmer gurus to not be any more effective then non swirling.So swirl all you want,but dont fool yourself into believeing that it increases performance as it does not.

RandyStace has a good write up on his site for a recirc skimmer thats based off the euroreef skimmers.There are also a lot of really good skimmer designs on this site that you can freely copy.
If you want some really good advice about building a skimmer,the 2 top people to speak to are Spazz and Hahnmeister.

HTH

[alpine]

Also personally I would "NEVER" use a rio pump for circulation,let alone a skimmer pump.There cheap pumps,always have been,and always will be.Nothing like putting your hand in your tank and getting the you know shocked out of you.

Been there and done that.When I worked in Chicago as a service tech for an lfs.The lfs I worked at sold rio pumps for all there setups.I had about 130 accounts that I did in a month.At least 3 times a week I was replaceing those stupid pumps for customers.This included there supposedly UL listed models as well.Also the only difference in the two is that the UL models have a thicker power cord.

Sorry had to rant about that as I saw the OP stated he was going to use a rio for his recirc pump.