Flow question

[dwdenny]

Ok I am working on my flow plan now. I was looking at using a Quiet One 4000 1017gph (unresricted). The pump has 1" MPT inlet and outlet and I was going to use 1" bulkhead for the input water.

1. Is 1" bulkhead large enough to supply water to this pump. I don't want to have the pump cavitate with to much water to it by using a 1.5" bulkhead and 1.5" PVC and reducing it at the pump. any suggestions?

2. How much loss can I expect with this about 1.5' verticle and same horizontal length. I looked at RC and said that output would be reduced to 768gph. Not sure if it is true or not. Will be using 1" PVC for plumbing with two outlets one in each corner reduced to 3/4" outlets on a 29g looking for about 25x to 30X turnover but will have a sump/fuge that will also add to this total. Looking at using a mag 7 for the sump return. With 1" bulkhead garvity fed to the sump may be too much flow through the sump/fuge not sure yet. Thanks for every ones help.

What does every one think. I have heard from other forums that a pump does not have head pressure in a closed loop system

[jaded]

1. It doesnt matter where the bottleneck is. If the intake of the pump is 1" you could put 4" pipe and it will still only be able to pull as much as it can through a 1" pipe.

2. What are you planning on keeping in this tank??? Thats a 28x turnover + a Mag7? Am I reading that right? I'm sure you'll hear other opinions but that seems like you could water ski in there.

closed loop- if you run the closed loop with a Mag7 thats hanging behind the tank you wont have to deal with head pressure, but if the pump ends up on the ground then you will have to deal with the head pressure returning to the tank. Theres also friction loss, but I dont think your going to have any trouble with flow, unless the trouble is to much of it.

I'm going to watch this post, I'm interested what everyone has to say

[dwdenny]

Semi closed loop it won't go around the tank basically like Marc from hidden treasures but with the intake drilled instead of HOB style www.melevsreef.com/closedloop.html minus the SWCD. The closed loop pump would be the quiet one 4000 or possible the 3000(780 gph) and will be right behind the tank only 18" to the top of the tank. The Mag 7 will be in the sump and have to pump up about 54" to the tank.

Most people I talk to are keeping about 30x turnover for sps at minimum shooting for medium flow (what ever that means) to me that is about 25X turnover or so.

[grapplert]

The head pressure you will have will be the vertical distance between the drain and the return. If they are the same height, no head pressure is created by pushing the water back up the return because an equal amount of water weight is pushing down in the drain. Although, you have to account for resistance created from plumbing (90's, 180's, etc.)

[dwdenny]

ok let me see if I got this right. If the intake is say 6" below the water line then the only head created is the difference between that point and the top of the tank ( I will be going over the tank for the return) which would be 6". The RC calculator is off big time I think will have to just use trial and error I guess.

[Thunderkat]

If you want to figure the head loss out exactly here you go....


http://www.unf.edu/~jwoolsch/Fluids/Pipes.doc

[dwdenny]

Gee thanks now I have to go back to school and get a Mathmatics degree j/k. :lol I will try to work it out and see what I come up with.

[grapplert]

ok let me see if I got this right. If the intake is say 6" below the water line then the only head created is the difference between that point and the top of the tank ( I will be going over the tank for the return) which would be 6". The RC calculator is off big time I think will have to just use trial and error I guess.

6" plus the plumbing...elbows, u-turns over top of tank, etc.

[dwdenny]

This might be good not sure anyone? www.geocities.com/Eureka/Concourse/3075/hazen2.html

[GeoB]

I have a Quiet One 3000 that I use for my return pump. From the outlet it goes to a tee and each tee goes to a scwd. I originally matched line diameter to the outlets: 1" from pump to scwds and 1/2" from scwds to tank. The flow was pathetic. So I switched to a 1.5" line from pump to tee and got a sizable increase in flow. Then I switched to 1" lines between the scwds and the tank outlets (that's a 1/2'' scwd outlet to a 1" line to a 3/4" flexi-joint outlet), and I got another sizable increase in flow.

To sum up, increasing the line diameters beyond the outlet diameters increased the flow dramatically. I think the Quiet One manual recommends a 1.5" return line. I'd also go with a 1.25" or 1.5" line between the pump and the bulkhead. Cavitation occurs when the pressure drops, a larger line should have more pressure. Quiet Ones lose flow quickly from back pressure, so avoid elbows where you can. They do have a nice power usage to flow ratio though.

[dwdenny]

I thought about using the Mag 9.5 for the loop and a mag 7 for the return heard they are good pumps but the power consumption to flow is a little high. I have heard a few problems as well not many just a few.

That is good information thanks. I will look at 1.25" instead of the 1" on both sides of the pump.