Plumbing Question

Sweet! Thank you!

 

I use soft tubing and threaded fittings pretty much exclusively. Another plus, besides those mentioned, is that it's very easy to change the system down the road if you need/want to do so.

The internal algae growth is easily fixed: use black tubing. Besides, black tubing looks sexy...at least Incognito thinks so (I'm her husband).

I agree that you don't want to restrict a pump's flow, esp. on the intake. If you want to reduce the flow on the return side, use a "bleed-off" valve and run it back to the sump:

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I dont plan on reducing the return flow. I just wanted to split the line coming from the overflow since I will have two seperate sections of the sump where the water will enter (the skimmer section and the fuge section). I want to "T" off the overflow line and put a valve on the line leading to the fuge so I can slow the flow through it. I plan on having both fuge and skimmer sections flow to a return section in the middle of the sump where the return pump will be.

 

Bleeding off the flow is a bad idea for a couple reasons. First, you need to understand how a centrifugal pumps and that is explained in Bernouli's Theory and the Laws of Affinity.
Basically a centrifugal pump only draws the power required to do the work presented to it, plus like any electrical device a little for heat and inefficiencies. So what this means is when you return flow to the sump as you suggested, you are producing more water (work) even though you are not using it or sending it to the dispaly, thus drawing more power and creating more heat.
When you valve or restrict the discharge you are reducing the flow (work) required, so your wattage and heat production go down accordingly. You are not harming the pump in any way, in fact it is often more efficient this way, more GPH for watts consumed.

I know it does not always make sense but this is how they work. If it were a positive displacement pump this would not apply but for all centrifugal pumps it applies, large or small.

 

Are you saying that I should over-size the return pump and valve the return line?

 

Most people slightly oversize the pump since gauging flow and head is always a guess at best, then install a ball or gate valve on the discharge side for both trimming or regulating the flow if needed and for isolation during pump cleaning and maintenance.

You obviously don't want to go too big but stepping up one size is usually recommended if you can swing it. Something else often recommended by pump manufacturers is to increase the inside diameter of the plumbing on the discharge side to reduce friction loss and line loss from fittings, bends and elbows. The same pump often pumps quite a bit more just by increasing the plumbing size from 3/4" to 1" even though the outlet nipple on the pump may only be 3/4". Danner Supreme/Mag recommends this in the literature that comes in the box with their pumps as do many others.

 

I noticed that. I am looking at the Eheim pumps to sit inside the sump and saw that the fitting on discharge was 5/8". I want to go at least 3/4", I'm thinking, so that I can plump the return to the tank. I also saw a post on 3reef where they used tubing with hose barb fitting from discharge of pump to the hard plumbing up to the DT. They used male threaded to screw into pump and then whatever sized hose barb on the other end. Figured I could run 3/4" tubing/hard plumbing barbed into the 5/8" fitting on the discharge of the pump.