Two pump CL sharing intake???

[DMBillies]

I just bought a 270 that has 8 holes for the closed loop in the bottom of the tank. The previous owner originally had a Dart (3600gph) and an OM feeding the outputs (each OM output split into 2 to feed all of them from the same pump).

I have a GenX PCX40 (about 1200gph) that I was thinking about using to feed 4 of the outputs constantly and keep 4 on the Dart/OM so I can get a nice wave effect in the tank. My hope also being that adding the extra flow from the additional pump would reduce the number of powerheads I need (or at least I would only need a couple to deal with dead spots).

Now the question...the original intake for the Dart used 1.5" plumbing. The most restricted point being around the bulkhead. The easiest way to run both pumps is to split the intake after the bulkhead and just plumb in the PCX40. However, I would be running close to 5,000 gph through the intake. I've heard it is generally bad to restrict the input side of a pump (which is what too small of plumbing would be doing basically), so I'm wondering if that's just too much water to pull through an intake like that?

I could use valves on the output side to reduce the amount of flow (they'll need to be there anyway in case I ever need to take the plumbing apart), but that kind of defeats the purpose of adding an extra pump.

Also, just to head off the suggestion... I'm not comfortable with drilling another intake hole in the tank, so I don't see that as an option (I have other options that are easier, less risky, and possibly more elegant solutions than that). I am really just hoping an engineer or experienced aquarist out there might be able to tell me if I'm out of my mind or point me to some information that might help me calculate whether it will work.

Thanks in advance.

 

[kcress]

Here's my take.

83 gal per minute sounds way to high for 1.5" Even if you can get that thru I wonder if it would be noisy and erode the pipe.

You don't generally want to exceed 5ft/sec flow in pipes or you can get into trouble. Especially lots of noise.

What you are proposing will cause a water speed of at least 15ft/sec.
A head loss of 1/2 a foot.
A pressure loss of 0.2psi

All on the suction side of pumps.

Also your suggested scheme includes some 90s which will greatly increase all these problems.

You need to do something else I think. Like <cough> another <cough>hole.

 

[Pbrown3701]

...or an over the top input. I use one on my CL and it works just fine.

 

[DMBillies]

I didn't really know exactly what trying that might do, but I assumed it was probably too much. The calculations put it into perspective though for sure.

On drilling another hole... I'm just not doing it. It is a used tank and if something went wrong with drilling it at this point, I'd own it. I cannot possibly afford to replace it if it breaks, so I'd have to sell off everything I've collected for this dream tank.

What I could do is use one (or two) of the 1" holes that had been for the CL outputs and dedicate them as intakes for PCX40 (would 1 be sufficient). What outputs I lose, I can easily make up for with powerheads high up in the tank (it is a 31" tall tank so I have plenty of headroom).

Pbrown... I was also thinking that. I could still use the under the tank outputs and just use an over the top intake. I hate the idea of having that plumbing in there though... I like the clean look you can get with CL's through the back/bottom.

Decisions, decisions... thanks for the input?

 

[kgross]

A single 1 inch bulkhead feeding the PCX40 would not be that bad. I would upsize the pipe at the bulkhead to 1.25 inch though, but the bulkhead will not cause a problem.

Kim

 

[Siffy]

<a href=showthread.php?s=&postid=12428162#post12428162 target=_blank>Originally posted</a> by DMBillies
Pbrown... I was also thinking that. I could still use the under the tank outputs and just use an over the top intake. I hate the idea of having that plumbing in there though... I like the clean look you can get with CL's through the back/bottom.

Decisions, decisions... thanks for the input?

Brian,
What about using one of the bulkheads for the Genx pump's intake and an over the tank wall output? Something like a Calfo style manifold (just a big ring around the perimeter of the tank with a Tee wherever you want an output). All you'd see looking into the tank are a few loc-line outputs. 1200gph could run several (6 or more maybe?) 1/2" outputs with plenty of velocity. 6 outputs would be just under 4 ft/s at each I believe, but don't quote me on that and it's not considering headloss. Just some more food for thought.

 

[wattsupdoc]

IMO, put it back like it was and add a couple 3 Koralia 4's. You get more flow out of those two than you'll get from the extra CL. I understand you'll see 'em, but they look pretty cool anyways.

Otherwise, pick one of the holes, use it for supply, upsize at bulkhead and use two returns.

 

[DMBillies]

Lot's of great ideas...

On the manifold idea, I had something similar on my 90, but I hated the way it blocks some light and gets in the way when I'm working in the tank. They are very versatile from a flow standpoint, but practically I thought mine was a pain.

I was planning on using 2 Koralia 4s at the top of each overflow with modded mounts to allow me to point them straight down. Idea being to keep stuff from settling in those back corners (I'm running barebottom). I was hoping the CL would handle the majority of the water motion in the front of the tank so that the OM can really have a chance to give a back and forth flow pattern which will look awesome with some of the LPS I have. I was figuring the Gen-X would just be the icing on the cake. I've made penductors for all of the CL outputs and I'm confident they will at least double the water circulated, so I think I can pretty easily provide just about all the flow I need without really cluttering up the tank more.

...and I suppose there is always the option of slapping a valve and a cap on the end of a few of the holes so I can use them in the future if I want/need to.