closed loop feed/return

[treesprite]

I have a Gen X pump rated 1580 gpx. My CPR overflow box had two 1" bulkheads. I originally meant to put that pump on a closed loop, but it is too strong to connect just one of the bulkheads to it.

 

I am wondering if I join together the bulkheads then connect it to the pump intake as 1 feed, would that then work? I don't want to go taking apart the plumbing on the overflow box if I'm not sure, because the guy I got it from had put putty on it instead of figuring something else out when it was leaking.

 

Or if the pump is too strong, is there a way to make it less strong?

Edited April 8, 2008 by treesprite

[Carl]

Here's my 2 cents...

 

I'm looking to use a Sequence Dart on my CL on my 75 gallon. When I looked up my pump online, it shows the various GPH at different head rates. If I put a ball valve on the return to the tank pipe, I can create an artificial head, and therefore slow down the flow...apparently without damage to the pump.

 

My pump is rated at 3600 GPH at 0 head, and 2820 at 4 feet of head. I assume my CL...without any real head...just friction...will pump somewhere between 3000 and 3200 GPH. At 3200 GPH, that's a turnover rate of 42 times/hour. Then I add in my Mag 5 for a return from sump to tank...and I believe I'll have WAY too much flow than I need.

 

So, I plan on putting in a ball valve in between the CL pump output, and the tank, to slow the flow down some.

 

On another note...I would never use an overflow box where somebody put some putty...and trust that it won't leak sooner or later...

 

-Carl

[treesprite]

So, if I slow down what comes out of the pump is that going to slow down how fast it sucks it in?

 

On the overflow box, I really need to take off the bulkheads I think and just replace them. Just afraid I'll mess something up. Maybe that's something someone can help me with at some point.

 

My next tank will be drilled, I promise that. I used to think it would make things more complicated... after a while it has become clear that only the opposite is true once a person starts adding sumps, fuges, loops, and what have you.

[Carl]

If I understand what I think you're trying to do...yes...if yo slow down what's going OUT of your pump back into the tank...it will naturally slow down what circles back around and into your overflow or sump.

 

Do you have both your bulkheads going to the pump? or just one?

 

Another note on my CL. I have two, 1.5 inch bulkheads in the tank. Each of these 1.5 inch pipes join together with a wye, into a single 2 inch pipe, that goes directly into the CL pump. DO NOT restrict this water flow into your pump. If you must, restrict it on the way OUT of your pump.

[ErikS]

Not certain I follow - "overflow" &/or "closed loop"?

 

In a drain configuration (as in the overflow) a 1" pipe will handle approx 600gph. Depending on the headloss this may or may not work out fine. As mentioned you can restrict the output of a pump with little ill effect on the pump (it simply "sees" it as more head).

 

If you're talking about a single vs dual (or more) intakes for a closed loop then yes, using two intakes will lessen the "suction" from each of the intakes. There's no real reason to throttle a closed loop, no worries about going beyond the capacity of any overflow. The only concern with a closed loop is making sure the pump has enough feed, if not it will cavitate (blow bubbles & harmful to the pump).

 

FWIW - at some point I would recommend replacing the CPR overflow, it's not a question of if it will fail, it's simply when. Absolutely abysmal design, almost as if they said "how can we make certain it will fail"?

 

I'd talk to Dan, surely he could make an amiracle/lifereef style overflow - shouldn't be terribly expensive.

[dbartco]

do something like this if you don't want to drill the tank. You don't need the scwd necesarrily. Don't use and overflow for a "closed loop".

 

http://www.melevsreef.com/closedloop.html

 

have at least 2 1" inlets sucking in. put a valve on the return to tank to modify flow

[Rascal]

So, if I slow down what comes out of the pump is that going to slow down how fast it sucks it in?

 

Under any and all circumstances . . . yes. A pump cannot take in more water than it is pushing out (unless it is leaking).

 

I agree with Dbartco -- wouldn't use an overflow for a closed loop. I'm not sure I'd even call that a closed loop. More like a sumpless return. Either way, it just seems to me there is an unnecessary risk of failure and headaches and I don't see any benefit to over using Melev's design. I think Bruce (bbyav) made something similar to this not too long ago. Do a search on here for "closed loop" and you should find the thread.

[treesprite]

thanks for all the advice.

 

I'd love to have my tank drilled but I'm not really up to emptying it at present. I would have to find someone to drill it for me, and if it broke I'd be out of luck because I can't afford a new tank.

 

I basically just want to get the powerheads out of the tank. I was able to take out a couple of them at least, with 3 openings on the return loop not capped, but I want more distribution which I can't have if all the flow is coming from the back of the tank. My only other option is to get the pump up higher to kill off some of the head - right now it is floor-level.

 

The CPR overflow box I believe does not itself fail, it's the suctioning out of air from it that fails. I have had a clogged airline, a broken aqualifter, and have had the airline come off. Aside from the risk factor and the noise, they do a decent job.

[treesprite]

i ended up making a kind of spray bar with 1/4 to 3/8" holes that zig-zags across the surface so it covers all areas of the tank (front, back, ends, middle). It works pretty well but needs some perfecting. I got to take out another powerhead and angled one of the last 2 a bit more upward to agitate the surface more.

 

Now, how do I get the flow through the spray bar evened out so that it isn't stronger at the beginning than the end? Disperse the holes a different way?

[tbittner]

i ended up making a kind of spray bar with 1/4 to 3/8" holes that zig-zags across the surface so it covers all areas of the tank (front, back, ends, middle). It works pretty well but needs some perfecting. I got to take out another powerhead and angled one of the last 2 a bit more upward to agitate the surface more.

 

Now, how do I get the flow through the spray bar evened out so that it isn't stronger at the beginning than the end? Disperse the holes a different way?

 

Can you post a pic of what you have? The way I built spray bars was to drill small holes, like 1/8" in a section of pipe. Cap the end of the pipe so they only way out is through the small holes. This generates a nice even flow from each of the holes because the pressure equalizes for the exit from the pipe.

[treesprite]

Can you post a pic of what you have? The way I built spray bars was to drill small holes, like 1/8" in a section of pipe. Cap the end of the pipe so they only way out is through the small holes. This generates a nice even flow from each of the holes because the pressure equalizes for the exit from the pipe.

 

 

I don't have a decent enough picture. I did exactly what you said - drilled holes and capped the end, though the holes didn't turn out to the same size because I was having a drill probelm - I'm planning to make a better one. What size are your holes, what pipe size, are there any turns, what size pump, covering what area?

[tbittner]

I used 3/4" pvc and it ran 18" along a side, then turned and ran 24" along the back. I have an overflow box so I couldn't take it all the way around the back. I drilled 1/8" holes, mostly along the bottom of the pipe but I did drill some, still angled down, but along the front of the pipe.

 

I have since removed it and replaced it with locline and nozzles because the water magnified the size of it and I didn't like the looks of it. I should have painted it black, then it probably wouldn't have been noticable.

 

My pump is a sequence barracuda but it's pumping up 16 feet from the basement to the 1st floor. I was still pumping around 1400 gph through that spray bar though.

Edited April 20, 2008 by tbittner

[Vader]

Hey Carl/treesprite......but I'm a building engineer for over 350,000 sq ft of office space, and I never close/adjust a valve on a suction side of a pump, but I do on the discharge side, but not more than 30%. I do this to avoid cavitation. The valve on the discharge side must be at least 3 times the diameter away from the outlet of the discharge of the pump. But that s on 800 ton cooling systems, but pumps are pumps......just a thought.

[tbittner]

Hey Carl/treesprite......but I'm a building engineer for over 350,000 sq ft of office space, and I never close/adjust a valve on a suction side of a pump, but I do on the discharge side, but not more than 30%. I do this to avoid cavitation. The valve on the discharge side must be at least 3 times the diameter away from the outlet of the discharge of the pump. But that s on 800 ton cooling systems, but pumps are pumps......just a thought.

 

I completely agree with this based on everything I've read. I DO put ball valves right next to the pump but they're wide open ALL of the time. I close them when I need to service the pump so I don't get a pipe full worth of water on the floor. My restriction ball valve is right behind the tank so I can adjust it and see what the effect is on the water.

 

Like I said though, my pump is in the basement and the tank is on the first floor...

Edited April 21, 2008 by tbittner

[Carl]

Hey Carl/treesprite......but I'm a building engineer for over 350,000 sq ft of office space, and I never close/adjust a valve on a suction side of a pump, but I do on the discharge side, but not more than 30%. I do this to avoid cavitation. The valve on the discharge side must be at least 3 times the diameter away from the outlet of the discharge of the pump. But that s on 800 ton cooling systems, but pumps are pumps......just a thought.

 

Thanks for the info...

[treesprite]

I used 3/4" pvc and it ran 18" along a side, then turned and ran 24" along the back. I have an overflow box so I couldn't take it all the way around the back. I drilled 1/8" holes, mostly along the bottom of the pipe but I did drill some, still angled down, but along the front of the pipe.

 

I have since removed it and replaced it with locline and nozzles because the water magnified the size of it and I didn't like the looks of it. I should have painted it black, then it probably wouldn't have been noticable.

 

My pump is a sequence barracuda but it's pumping up 16 feet from the basement to the 1st floor. I was still pumping around 1400 gph through that spray bar though.

 

One thing I didn't ask is, how far apart are your holes? Since you have more experience with this than I do, I'm going to try it kind of your way. My final product will definately be painted black.