reducing head ?

[valid]

i would like to employ an ampmaster 3000 for my saltwater tank. the problem is that i am forced to have three 90*s hard plumbed at the back of the tank, and i am worried this will create unecessary head. can i noticeably alleviate this by plumbing 2" lines instead of the standard 1.5" lines after the pump? the immediate area where these elbows are located involves about 2 ft of vertical and 2.75 ft total line length at the back of the tank. total line after the pump is about 7 ft and total vertical is 3.5 ft.

so: if this idea even makes a difference, should i have the entire line run at 2", or just the area where the elbows are?

 

[Tom Provatas]

I have an ampmaster pump on my tank and the fitting coming of the pump accomodates 21/2" pvc.

 

[valid]

it comes plumbed in/out at 1.5" (not 2.5")as per their website - i haven't actually checked myself because that's not really what i am asking. one may use adapters to go to whatever diameter is desired. i merely wish to resolve some head issues w/ my own plumbing design.

any ideas?

[ February 25, 2002: Message edited by: valid ]</p>

 

[M.E.Milz]

Increasing the diameter of the pump should help to reduce head loss at the elbows by reducing the velocity of the water flowing therethrough. Using longer radius elbows, or flexible tubing with gradual bends will also reduce head loss. How much? I DNK. Anything is bound to help since the Ampmaster 3000 is a low rpm pump, and therefore sensitive to backpressure.

 

[kgross]

The best solution to decreasing head loss is to increase the size of the plumbing. Going from 1.5 inch to 2 inch plumbing increases the flow capacity by almost double. So be increasing the size the effect of the elbows will be reduced to basicly nill.

I always suggest using larger plumbing than you think you need, it will give you a lot more flow.

 

[Anonymous]

I look at this differently. I would figure out what type of flow rate I wanted based on tank size, tank turn over, whether or not you will be using powerheads or a closed circuit system to add flow, ect. Then you can use the head calculator at http://www.reefcentral.com/calc/hlc.htm
Then I would look at pumps to see which had enough head pressure to get the flow you want. You can then vary the piping size and see how much it helps reduce the head and whether or not that really makes a difference in your pump selection.
Picking the pump first seems backward to me.

 

[M.E.Milz]

I agree with cwa46 - figure out what kind of flow you want, and how much head/pressure loss you have, before try to figure out what is the best pump for you. Many pumps that work great for certain applications are just not designed for other applications.

Take the Ampmaster 3000 for example. This is a low rpm pump that works great for high flow, low head applications, but not so great for high head applications (which is typical of low rpm pumps). In other words, the Ampmaster 3000 might work great for a closed loop return system, but not so great if you are pumping the water up a distance from a sump.

When I was sizing the return pump for my new tank, I knew that the 6' of head and other pressure losses would cut the flow of the Ampmaster 3000 in half, which was too low for my tank. I ended up with a Dolphin 4500, which is a high rpm pump (with higher energy demands) that can give me 2500 gph at 17' head.

 

[mickyryan]

Hi i work with plumbing non potable water systems every day and what most folks have said is true
now as far as the flow rsates go you will never get max flow from any pump with more head then they are designed and rated at in otherwords take a pump that says it will flow 1500gph at 3 ft of head well its pretty hard to get only 3 ft of head period. so that pump would actually be flowing about 1300gph in most cases, also increasing pipe size is fune but rule of thumb the intake should always be double the return size that way you get no pump cavitation unless you are putting the pump below water level then id still double but it will always be easier on the pump. if at al possible heatbend all plumbing instead of using tight premaid fittings
if you would like more technical terms i could post flows and friction losses for plumbing but best bet is double the size you think youi need and throttle it back most pumps like a little bit of a load .

 

[Enkidu]

Wow, its hard to follow that post; but I'll try.

Maybe you could try 45 degree elbows instead of the 90's?

 

[Mac1]

Using 2x45's instead of 1x90's will cut some of the head loss down. The best bet is some oversized Flexi tubing however. When I moved into my house, I took the opportunity to re-do some of the plumbing on my tank. Had been using an Eheim 1050 Hard plumbed w/ 3/4" PVC (3-4 90's in there as well). I switched it to 1.5" Flexi Tubing, and added a 1" Sea Swirl (2x1" 90's), and it was an incredible difference. The bulk of it I attribute to using the fatter tubing (as the Eheim is rated for 4' Head), but using Flexi instead of hard PVC to overcome some of the head loss w/ all the twists and turns really made a difference as well.

- Mac

 

[wade1]

What about flex PVC? Can you make that fit?

 

[M.E.Milz]

When using flexible tubing, go with spa tubing sold by most Home Depots. The stuff is white, so it won't cause algae to build up on the inside. But more importantly, the stuff is really stiff, so it won't faltten in the curves and will only allow gradual curves, both of which will help to hrsd headloss. The biggest problem is trying to force it over the end of a hose barb.