Return pump question for new build

[Hetfield6j]

Hello. I am recently getting back into the hobby after about a 12 year break. I just purchased an IM 150g lagoon tank and a bashsea 36” sump. I have never plumbed a tank before so I have been reading articles here on this website as well as watching a lot of online videos. I feel like I have learned a lot and have started to make some of the plumbing purchases as well. The return pump I purchased is a sicce 9.0 which has a 1” return outlet. I noticed that my tank has 2 3/4” returns on the back. I thought I had read that you should not go from a large outlet to a smaller outlet on your return, or is this ok since it is going to split from the single 1” to two 3/4”? Hopefully how I explained it makes sense as I am still new to plumbing. Thanks for any help!

 

[RocketEngineer]

I’m not sure where you read that as it doesn’t make sense. You are fine.

 

[BOYERZ]

I’m not sure where you read that as it doesn’t make sense. You are fine.

Probably back pressure, he's fine.

 

[vetteguy53081]

Hello. I am recently getting back into the hobby after about a 12 year break. I just purchased an IM 150g lagoon tank and a bashsea 36” sump. I have never plumbed a tank before so I have been reading articles here on this website as well as watching a lot of online videos. I feel like I have learned a lot and have started to make some of the plumbing purchases as well. The return pump I purchased is a sicce 9.0 which has a 1” return outlet. I noticed that my tank has 2 3/4” returns on the back. I thought I had read that you should not go from a large outlet to a smaller outlet on your return, or is this ok since it is going to split from the single 1” to two 3/4”? Hopefully how I explained it makes sense as I am still new to plumbing. Thanks for any help!

I have mine reduced to the filter socks with no issue

 

[BOYERZ]

I have mine reduced to the filter socks with no issue

I think it's regarding the pump side. Now I'm a bit confused.

 

[vetteguy53081]

I think it's regarding the pump side. Now I'm a bit confused.

If so, my pump return is a solid 1" all the way up and I too have a Bashsea sump

 

[Hetfield6j]

I think it's regarding the pump side. Now I'm a bit confused.

ya, I am talking about from the return pump in the sump back to the tank. I had read that undersizing the return could cause cavitation I believe at the pump and damage it.

 

[BOYERZ]

If so, my pump return is a solid 1" all the way up and I too have a Bashsea sump

Ya, neck down or up.

 

[vetteguy53081]

Ya, neck down or up.

Both. I run a Sicce 5.0 and its 1" from the pump up to the bulkhead. At top of bulkhead is 1" line running to the tank (durso configuration). For the overflow is 1.25" to the bulkhead and below the bulkhead is 2.25" reduced to 1" at the inlets to the socks. System is dead quiet and no flow issues

 

[BOYERZ]

ya, I am talking about from the return pump in the sump back to the tank. I had read that undersizing the return could cause cavitation I believe at the pump and damage it.

It can, but you would have to neck down to a 1/4" or so.

You can test this theory by adding a ball, or gate valve after the pump.

As you reduce flow the pump will become noisy.

You will be fine going from 1" to a tee then reducing to (2) 3/4 returns.

 

[Hetfield6j]

It can, but you would have to neck down to a 1/4" or so.

You can test this theory by adding a ball, or gate valve after the pump.

As you reduce flow the pump will become noisy.

You will be fine going from 1" to a tee then reducing to (2) 3/4 returns.

Makes sense. I figured as much but just wanted to make sure. I appreciate the help everyone!

 

[Bruttall]

Reducing the diameter of the flow pipe will increase pressure behind the reduction, adding load to your pump. It has to work harder because there is back pressure. This sorta helps illustrate.




The other factor most miss when doing DIY is what corners, or bends do to the flow rates. I think this also bears mentioning. Here is a diagram that illustrates. This the reason why 45 degree elbows or 90 degree sweeps are used.


The last thing I feel the need to mention is that your pumping from a 1 inch into a pair of 3/4inch, effectively increases the diameter of your flow, after a slight reduction at the Y fitting, overall you should not notice any additional load on your pump by plumbing that way.

 

[RocketEngineer]

Pumps are designed to have back pressure. Otherwise the prop would be free spinning in the housing. In fact, some pumps are more efficient (watt used for a given gph) within a given range of back pressure. The goal is to use pumps in the middle of that range, not at the extremes.