question on water inlet for recirculating skimmer

[mattboy]

Hi;

I'm about finished up with my initial design for a recirculating skimmer; I'm using a sedra 5000 as a pump and about 18" of 6" tube for the main reaction chamber. I'm building a small box under the tube for the plumbing; I don't want to drill any holes in the tube. So, for example, the pump output will go into the box and up a PVC pipe in the tube with an elbow; I can vary the length of the PVC pipe and in this way adjust where the pump output is in the tube. The pump input will draw water for recirculation from near the tube/box joint. My main question is, can I feed the skimmer by putting a tee in the PVC line from the pump input to the box, with a PVC pipe running from the tee up to the water level outside the tube.

This is similar to the way calcium reactors are fed water; new water enters the plumbing loop just before the input to the circulation pump, and gets mixed with the water coming into the pump from inside the reactor, then that goes through the pump and into the reactor. When I think about it, I guess the plumbing loop for a recirculating skimmer could be the same, couldn't it?

What I'm concerned about is how the movement of water through the recirc loop would affect the ability to push water into that loop (it should draw the water in, actually) and if any of this would affect the venturi, which will be right at the pump input.

Thanks for any thoughts on this; sorry I don't have the software or knowledge to post a diagram.

 

[Spuds725]

I don't think I can answer your question exactly-- it might affect its ability to pull air in via the venturi... how would the water get to the pump... is the pump going to be pulling it out of the sump as well as the recirc loop or will it be gravity fed... if gravity, there might be backpressure that would affect it.

My DIY (I bought it from someone else who built it) recirc skimmer is fed by gravity from the tank-- enters about 8 inches above my pumps (dual Sedra 3500s).

I have to run my flow pretty low to get it produce skimmate (less then 100 GPH)-- I'm still tweaking it-- have done a few mods....

here is is before I installed it..

Is there some reason why you don't want to add a seperate input??

Also I'm not sure how you are bulding it but you might want to try and a make a tapered neck (funnel shapped) up to the riser-- mine has a flat flange that the bubbles fromt he reaction chamber get caught on-- i recently added a neck section-- all I did was cut out the top of a water cooler bottle and wedged this in the body so the top of it is even with the riser-- seems to help somewhat.

I've read of people making these by heating sheets of acrylic with a gun or in an oven... be careful of fumes if you try this.

 

[mattboy]

The way you have your drain pipe is really similar to what I'm thinking of, if I'm seeing yours correctly. There's a fitting in the top of the box, and the drain pipe rises from this, correct? Is that even a little box on the bottom of your tube, or just a square bottom?

Okay, so instead of the pump connections going into the side of the tube, picture fittings in the side of the little box, then some PVC elbows and pipe going up into the tube; that's how my recirc loop will be plumbed. Regarding the feed, I was thinking of gravity feed from the tank, with a gate valve on the input side to control flow through. I'm not concerned about back pressure; I think if anything the movement of the water through the plumbing will draw water down. (I'm worried about too much draw) This tee would located a couple of inches before the venturi in the loop. The whole idea behind this is to introduce water into the skimmer through the pump, as it would immediately get foamed, and would save me from drilling a hole in the tube. If it does not work, I can always take the tee out of the loop and drill the tube; at least it's a hole up high.

 

[Spuds725]

<a href=showthread.php?s=&postid=6716244#post6716244 target=_blank>Originally posted</a> by mattboy
The way you have your drain pipe is really similar to what I'm thinking of, if I'm seeing yours correctly. There's a fitting in the top of the box, and the drain pipe rises from this, correct? Is that even a little box on the bottom of your tube, or just a square bottom?

Yep that is correct-- it is a box on the bottom-- I have veritcal pipe on the back side attached to the base by a bulkehead-- the top is vented and then there is a loop going back down off this with a gate valve to set the water level. My pump intakes do take in some aerated water already.

Okay, so instead of the pump connections going into the side of the tube, picture fittings in the side of the little box, then some PVC elbows and pipe going up into the tube; that's how my recirc loop will be plumbed. Regarding the feed, I was thinking of gravity feed from the tank, with a gate valve on the input side to control flow through. I'm not concerned about back pressure; I think if anything the movement of the water through the plumbing will draw water down. (I'm worried about too much draw) This tee would located a couple of inches before the venturi in the loop. The whole idea behind this is to introduce water into the skimmer through the pump, as it would immediately get foamed, and would save me from drilling a hole in the tube. If it does not work, I can always take the tee out of the loop and drill the tube; at least it's a hole up high.

I think I get your setup, but don't know how well it will work-- I'm afraid you will have to just try it unless someone else has a similar design as you and sees this.... Good luck...