Major plumbing problems with new setup

[CC13]

Maybe....maybe not. In both cases the water is being pumped/flowed at a constant rate and the variable is the transition.

Not really. Water under pressure from a pump might pump the same volume (regardless if 90's or 45's are used) as the BRS video displayed if the pump is strong enough to overcome the head pressure and friction.

When water comes from an overflow its velocity is determined only by gravity and when it slows down (transitions suddenly from a free fall to a 90 degree horizontal run), there is nothing to re-accelerate that water back up... except for water behind it. Hence why it backs up.

Its much more difficult to plan out your return lines when adding in lots of runs over a long distance because backing up becomes more of an issue.

 

[jtl]

Not really. Water under pressure from a pump might pump the same volume (regardless if 90 or 45's are used) as the BRS video displayed if the pump is strong enough to overcome the head pressure and friction.

When water comes from an overflow its velocity is determined only by gravity and when it slows down (transitions suddenly from a free fall to a 90 degree horizontal run), there is nothing to re-accelerate that water back up... except for water behind it. Hence why it backs up.

This same principal is why you need only 1 return line and 2-3 overflow lines.

You should have multiple over flow pipes in case the main drain becomes restricted/plugged after you set your flow rates to the sump. This is an after the fact occurrence and has nothing to do with flow rates and pipe bends. The latter will only slow things down. I still believe that the difference if any between a 90 and 2-45's is inconsequential. Both will slow the flow, the bigger issue is vertical drop and pipe size. A durso may have a different effect since the water is mixed with air and is turbulent unlike a full siphon. Not trying to be argumentative but we clearly have a difference of opinion. I would love to experiment but I don't think I have a big enough vessel to hold the supply water. I will check to see if I have a bulkhead in my plumbing box that I can put in one of my 10g totes. It would certainly be good information either way.

 

[CC13]

You should have multiple over flow pipes in case the main drain becomes restricted/plugged after you set your flow rates to the sump. This is an after the fact occurrence and has nothing to do with flow rates and pipe bends. The latter will only slow things down. I still believe that the difference if any between a 90 and 2-45's is inconsequential. Both will slow the flow, the bigger issue is vertical drop and pipe size. A durso may have a different effect since the water is mixed with air and is turbulent unlike a full siphon. Not trying to be argumentative but we clearly have a difference of opinion. I would love to experiment but I don't think I have a big enough vessel to hold the supply water. I will check to see if I have a bulkhead in my plumbing box that I can put in one of my 10g totes. It would certainly be good information either way.

Might make for a good BRS test video? LOL

Ya I don't really agree but hey, that's what this forum is for.... good discussion

 

[PNWCoralFarmer]

Appreciate the commentary, gentlemen. It blows my mind that there is all this discussion on return pump plumbing and its affect on increased head pressure, but the same discussion about drain pipes never seems to occur. Had I known this, I would have had the pass through placed differently and optimized for the drain pipes instead of the return.

I think the real factor here is the 1" pipe combined with only a 2.5 foot drop. I cant do anything about the drop as my tank stand and sump stand are what they are. The only real factor I can control is the 1" pipe, or cut a second hole in the wall which isn't really feasible.

At the moment I have modified the overflow to use 1 pipe running at full siphon, 1 pipe running at a full siphon dialed back by the gate valve, and the third pipe as the emergency. I realize this sacrifices some redundancy, but I frankly can't imagine a how anything would get in to the overflow box through the sealed top, or through the weir that is very firmly in place.

Thoughts?

 

[joekool]

When figuring out the flow for my siphon drains and sizing I read this. Yes water is pulled by gravity. It (for our purposes) behaves like a solid when it is confined by a pipe, so the further it falls, the faster it falls. It pulls on the water above it as well. I will leave it to you to research if the "pull" is created by surface tension or displacement In any case we use the basic Bernoulli equation to explain how much water falls how fast.
Lets take the 2" SCH80 Bulkhead with a 1.913 inch I.D. and 48" of head. h = "height" and denotes the head (water height) above the hole. g = "gravity" denotes the free fall of an object here on earth.. (32ft/sec)squared So we find the velocity and then plug it into the basic formula: Q = A * V
Lets do some math: 2" SCH#80 PVC pipe I.D. = 1.913 inches.
So: h= 6" = 4' A= 2.873" sq. = 0.01995' sq. g= 32f/s sq. Find the Velocity: V = sqrt(2* 32f/s^2 * 4f) = 16f/s Find the flow rate (Q): Q= 0.01995f^2 * 16f/s = 0.3192 Cubic Feet per Second.
The Result: 0.3192 Cubic Feet per Second = 143.25 Gallons Per minute 143.25 Gallons per Minute = 8595 Gallons Per Hour.
Long drop, lots of pipe and fittings... lets say 7250 GPH Now... the larger the drop, the more friction and turbulance affect the velocity and therefore, the overall flow. Also note that "terminal" velocity is reached much faster due to the friction and turbulance and that cavitation can occur if the pressure drop (caused by the water falling through the pipe) exceeds the surface tension of the water itself....

 

[joekool]

Also have this chart for rough idea as well. the "head height" is the total distance from the intake pool level to the discharge pool level or pipe exit (if the pipe exits above water). The "bulkhead diameter" refers to the narrowest section in the drain.

 

[MARK M. DAVIS]

http://www.beananimal.com/articles/hydraulics-for-the-aquarist.aspx

 

[PNWCoralFarmer]

http://www.beananimal.com/articles/hydraulics-for-the-aquarist.aspx

I saw this earlier, but the calculator is gone and I was struggling to plug in the right units.

Also from that link:
Given a standard 1" bulkhead that has an internal diameter of 1.033" attached to a pipe of the same diameter, and the pipe drops 24" to the sump. The head height would be 24" and the Pipe/Orifice Diameter would be 1.033". Clicking the "calculate" button will show that the maximum flow rate (full siphon) would be about 1,700 GPH.

This is basically my exact scenario, and I am flowing less than half of that...