PVC plumbing question (first time working with PVC)

VoidRaven · 09/26/2006, 08:17 PM

Ok, I'm not new to the hobby but I am new to PVC work and putting together my own return....with that in mind, please read on:

First off....I do not understand plumbing...especially PVC.

I working on putting together a new system and had a PVC plumbing question. I'm using a Little Giant 3MDQX-SC as the return pump on a 100g display with a 20g sump (120g total volume). The input and output on the pump is 1". For the return I want to split the output so at the end of the 1" return line I'm going to put a 1" to 1/2" elbow which feeds a 1/2x1/2x1/2 "three way" PVC 90 degree "elbow with input on the side" type piece.

So essentially I'm going from 1" down to 1/2" and then splitting that 1/2" into two 1/2" nozzles. The distance from the pump to the beginning of the return nozzle assembly is about 4 feet.

Is this OK??? Can this be done or am I going to be creating problems? I've purchased everything but have not assembled any of it yet so I can take it back if I need to. Finding parts is a pain though.

Oh yeah, and anyone know where I can get 1 1/4" ID round gaskets to put between the PVC and the glass???

Konadog · 09/26/2006, 08:31 PM

Yes, its OK............ but you will lose some flow from your pump by reducing it to 1/2" before the split. If you reduce it after the split at the outlet, you will still loose some, but not as much.

What do you need the gaskets for? Have you looked at using O-ring?

bertoni · 09/26/2006, 08:33 PM

I would split the return into 3/4" lines or larger, to reduce the back pressure.

I don't know where to get the gaskets by themselves, but a bulkhead kit should have them.

VoidRaven · 09/27/2006, 05:02 AM

The reduction to 1/2" is on a 90" piece....that piece links into a short section (maybe 2 1/2" inches) that leads to the split 1/2" "elbow type piece" that is the end of the return. I'm thinking now that this is bad?

So what it *should* be is 1" all the way and then a 1" to 1/2" or 1" to 3/4" reducer at the very end of the outlet? Am I understanding that correctly?

The problem I have is that the tank was not drilled/built/run with bulkheads...the original system was all PVC. They had these flat o-ring things (which I call gaskets) between the PVC and glass to help with the seal. The system was run for a couple years with no problems according to the previous owner (who is quite experienced with this stuff) so its original configuration obviously works. I'm essentially just trying to rebuild/reconstruct it.

*sigh* This is why I never ran sumps before....I hate plumbing and never wanted to mess with it on a reef tank. Now I have to and am really confused. Plus trying to find the right parts is a pain! Lowes and HD are really the "best" (and I use that term loosely) plumbing supply stores near me that I am aware of.

Any other thoughts? Ideas? Pics of DIY returns? HELP!

hodsgod · 09/27/2006, 05:35 AM

You definitely shouldn't reduce the size of the pipe until you split from the one inch to the two half inch pipes.

I would recommend that you have a one inch tee piece and then reduce down to the half inch pipe after the tee. That way you will maximise the flow.

Don't forget that the two half inch tubes added together are smaller in volume than the one inch tube.

Shagsbeard · 09/27/2006, 05:40 AM

I second the 3/4" idea. Flow is determined by area, and area is proportional to the square of the diameter. This makes 1/2" only support 1/4th the flow for the same velocity... meaning your water is going to speed up a whole bunch. When it speeds up, it produces cavitation, which causes two things: noise and bubbles... neither of which you want. I wouldn't reduce the size at all... and stick to 1", but at least 3/4" won't speed your water up... (math altert: 2x(3/4)^2=18/16>1).

To push PVC through a glass hole, you want what is called a bulkhead. You buy the bulkhead to fit the hole in the glass, not the size of pipe you have. A bulkhead comes with the washers and gaskets that you need. My local HD doesn't have bulkheads. It's got a very poor selection of plumbing suplies. Our best plumbing store is a farm supply place... they have everything. Phone book is probably your best bet to find plumbing stuff. You can order them from the internet too.

Edit for more PVC tips: You want to join PVC with primer (purple stuff) and PVC cement. PVC cement actually melts the PVC into each other... it becomes a single piece. Read the instructions on the jar carefully. For threaded PVC (more expensive, more leak prone, but can be disassembled) you want to wrap the threads in a couple or three layers of teflon tape. Wrap the male thread in the same direction that you will be screwing in the piece.

On your return pipe, just below the surface of the water in your main tank, drill a small hole (some use two) to allow air to enter the pipe in case of a power outage so that you don't drain your tank into your sump. During normal opperation, water will be spaying out of this hole, so keep the hole below the surface of the water. Without the hole, your return will act as a siphon and remove all the water from the tank above it.

NewSaltyReefer · 09/27/2006, 05:48 AM

Definately do not reduce twice. I did exactly what hodsgod suggested on my system but I only reduced to 3/4.

I also know what you are talking about with the gasket thing. I have an overflow I picked up at an LFS that has a drain like that. I took me a while to get it to stop leaking so if you can I would switch to a standard bulkhead.

VoidRaven · 09/27/2006, 07:18 AM

Thank you everyone so far for your comments....Shagsbeard, I'm kind of disturbed because I understood almost everything you said including the math!

Bulkhead question...All the piping is 1"....including the in-tank overflow. Hole was made to fit 1" PVC....how does a bulkhead work for that? I thought the bulkhead would make the hole smaller meaning smaller piping? What am I misunderstanding here?

VoidRaven · 09/27/2006, 07:53 AM

Oh, I forgot to mention that the ONLY hole in the tank is for the overflow and one in the sump (to feed the return pump)....the return assembly has to be sort of a "hang on tank" thingy because I'm not drilling the tank for a return.

bertoni · 09/27/2006, 12:23 PM

A 1" bulkhead should be fine, although the hold might need to be redrilled.

Liquid Hobby · 09/27/2006, 12:53 PM

I just did the plumbing on my first reef tank. Quite the learning experience... Had to make many trips to get more parts. Biggest learning I had was pipe size, the bigger the pipe, the more flow you will get, due to less restriction.

One of my pumps has 1" in and out fittings. I have 1 1/2" going in, reduced just at the fitting and 1 1/4" going out, expanded just at the fitting, which is reduced through a bukhead to 3/4 outlets.. Vastly better flow than my previous all 3/4" plumbing!!

Here's a pic, it's not my return, but you get the idea...

VoidRaven · 09/27/2006, 01:17 PM

Thanks Liquid Hobby....that does help me out a bit! I can see where I have some fresh re-planning to do.

09/26/2006, 08:17 PM	#1
VoidRaven 'tis himself Join Date: Jun 2004 Location: York Township, OH Posts: 1,829	PVC plumbing question (first time working with PVC) Ok, I'm not new to the hobby but I am new to PVC work and putting together my own return....with that in mind, please read on: First off....I do not understand plumbing...especially PVC. I working on putting together a new system and had a PVC plumbing question. I'm using a Little Giant 3MDQX-SC as the return pump on a 100g display with a 20g sump (120g total volume). The input and output on the pump is 1". For the return I want to split the output so at the end of the 1" return line I'm going to put a 1" to 1/2" elbow which feeds a 1/2x1/2x1/2 "three way" PVC 90 degree "elbow with input on the side" type piece. So essentially I'm going from 1" down to 1/2" and then splitting that 1/2" into two 1/2" nozzles. The distance from the pump to the beginning of the return nozzle assembly is about 4 feet. Is this OK??? Can this be done or am I going to be creating problems? I've purchased everything but have not assembled any of it yet so I can take it back if I need to. Finding parts is a pain though. Oh yeah, and anyone know where I can get 1 1/4" ID round gaskets to put between the PVC and the glass??? __________________ "If the women don't find you handsome, they should at least find you handy." - The Red Green Show Current Tank Info: 24g BioCube reef

09/26/2006, 08:31 PM	#2
Konadog Master of the 16 hour day Join Date: Feb 2002 Location: East Long Beach, So Cal Posts: 13,151 Blog Entries: 4	Yes, its OK............ but you will lose some flow from your pump by reducing it to 1/2" before the split. If you reduce it after the split at the outlet, you will still loose some, but not as much. What do you need the gaskets for? Have you looked at using O-ring? __________________ Save the Reefs................................................................Save the world! -Ken Current Tank Info: Currently tankless, and loving it!

09/26/2006, 08:33 PM	#3
bertoni RC Mod Join Date: Mar 2002 Location: Mountain View, CA, USA Posts: 88,616	I would split the return into 3/4" lines or larger, to reduce the back pressure. I don't know where to get the gaskets by themselves, but a bulkhead kit should have them. __________________ Jonathan Bertoni

09/27/2006, 05:02 AM	#4
VoidRaven 'tis himself Join Date: Jun 2004 Location: York Township, OH Posts: 1,829	The reduction to 1/2" is on a 90" piece....that piece links into a short section (maybe 2 1/2" inches) that leads to the split 1/2" "elbow type piece" that is the end of the return. I'm thinking now that this is bad? So what it should be is 1" all the way and then a 1" to 1/2" or 1" to 3/4" reducer at the very end of the outlet? Am I understanding that correctly? The problem I have is that the tank was not drilled/built/run with bulkheads...the original system was all PVC. They had these flat o-ring things (which I call gaskets) between the PVC and glass to help with the seal. The system was run for a couple years with no problems according to the previous owner (who is quite experienced with this stuff) so its original configuration obviously works. I'm essentially just trying to rebuild/reconstruct it. sigh This is why I never ran sumps before....I hate plumbing and never wanted to mess with it on a reef tank. Now I have to and am really confused. Plus trying to find the right parts is a pain! Lowes and HD are really the "best" (and I use that term loosely) plumbing supply stores near me that I am aware of. Any other thoughts? Ideas? Pics of DIY returns? HELP! __________________ "If the women don't find you handsome, they should at least find you handy." - The Red Green Show Current Tank Info: 24g BioCube reef

09/27/2006, 05:48 AM	#7
NewSaltyReefer Registered Member Join Date: Dec 2005 Location: Melbourne, FL Posts: 96	Definately do not reduce twice. I did exactly what hodsgod suggested on my system but I only reduced to 3/4. I also know what you are talking about with the gasket thing. I have an overflow I picked up at an LFS that has a drain like that. I took me a while to get it to stop leaking so if you can I would switch to a standard bulkhead. __________________ Please can I upgrade my tank...PLEASE...PRETTY PLEASE!! Current Tank Info: 29g Reef

09/27/2006, 05:35 AM	#5
hodsgod Registered Member Join Date: Jan 2006 Location: Yokohama, Japan Posts: 155	You definitely shouldn't reduce the size of the pipe until you split from the one inch to the two half inch pipes. I would recommend that you have a one inch tee piece and then reduce down to the half inch pipe after the tee. That way you will maximise the flow. Don't forget that the two half inch tubes added together are smaller in volume than the one inch tube.

09/27/2006, 05:40 AM	#6
Shagsbeard Registered Member Join Date: Jul 2006 Location: Morro Bay, CA Posts: 2,143	I second the 3/4" idea. Flow is determined by area, and area is proportional to the square of the diameter. This makes 1/2" only support 1/4th the flow for the same velocity... meaning your water is going to speed up a whole bunch. When it speeds up, it produces cavitation, which causes two things: noise and bubbles... neither of which you want. I wouldn't reduce the size at all... and stick to 1", but at least 3/4" won't speed your water up... (math altert: 2x(3/4)^2=18/16>1). To push PVC through a glass hole, you want what is called a bulkhead. You buy the bulkhead to fit the hole in the glass, not the size of pipe you have. A bulkhead comes with the washers and gaskets that you need. My local HD doesn't have bulkheads. It's got a very poor selection of plumbing suplies. Our best plumbing store is a farm supply place... they have everything. Phone book is probably your best bet to find plumbing stuff. You can order them from the internet too. Edit for more PVC tips: You want to join PVC with primer (purple stuff) and PVC cement. PVC cement actually melts the PVC into each other... it becomes a single piece. Read the instructions on the jar carefully. For threaded PVC (more expensive, more leak prone, but can be disassembled) you want to wrap the threads in a couple or three layers of teflon tape. Wrap the male thread in the same direction that you will be screwing in the piece. On your return pipe, just below the surface of the water in your main tank, drill a small hole (some use two) to allow air to enter the pipe in case of a power outage so that you don't drain your tank into your sump. During normal opperation, water will be spaying out of this hole, so keep the hole below the surface of the water. Without the hole, your return will act as a siphon and remove all the water from the tank above it.

09/27/2006, 07:18 AM	#8
VoidRaven 'tis himself Join Date: Jun 2004 Location: York Township, OH Posts: 1,829	Thank you everyone so far for your comments....Shagsbeard, I'm kind of disturbed because I understood almost everything you said including the math! Bulkhead question...All the piping is 1"....including the in-tank overflow. Hole was made to fit 1" PVC....how does a bulkhead work for that? I thought the bulkhead would make the hole smaller meaning smaller piping? What am I misunderstanding here? __________________ "If the women don't find you handsome, they should at least find you handy." - The Red Green Show Current Tank Info: 24g BioCube reef

09/27/2006, 07:53 AM	#9
VoidRaven 'tis himself Join Date: Jun 2004 Location: York Township, OH Posts: 1,829	Oh, I forgot to mention that the ONLY hole in the tank is for the overflow and one in the sump (to feed the return pump)....the return assembly has to be sort of a "hang on tank" thingy because I'm not drilling the tank for a return. __________________ "If the women don't find you handsome, they should at least find you handy." - The Red Green Show Current Tank Info: 24g BioCube reef

09/27/2006, 12:23 PM	#10
bertoni RC Mod Join Date: Mar 2002 Location: Mountain View, CA, USA Posts: 88,616	A 1" bulkhead should be fine, although the hold might need to be redrilled. __________________ Jonathan Bertoni

09/27/2006, 12:53 PM	#11
Liquid Hobby Registered Member Join Date: Oct 2005 Location: Portland, OR Posts: 810	I just did the plumbing on my first reef tank. Quite the learning experience... Had to make many trips to get more parts. Biggest learning I had was pipe size, the bigger the pipe, the more flow you will get, due to less restriction. One of my pumps has 1" in and out fittings. I have 1 1/2" going in, reduced just at the fitting and 1 1/4" going out, expanded just at the fitting, which is reduced through a bukhead to 3/4 outlets.. Vastly better flow than my previous all 3/4" plumbing!! Here's a pic, it's not my return, but you get the idea... __________________ 120 DT/200 G mixed reef: birthed on Dec 1, 2010 * Neptune Systems controller * 40G Sump + 40G Fuge which gravity feeds into DT * Huge Reef Octopus Skimmer * Calc, GFO and Carbon RXs * 2x250W 20K Radium MH with VHO supplement * 3600 GPH closed loop with OM 4 way * 1700 GPH return

09/27/2006, 01:17 PM	#12
VoidRaven 'tis himself Join Date: Jun 2004 Location: York Township, OH Posts: 1,829	Thanks Liquid Hobby....that does help me out a bit! I can see where I have some fresh re-planning to do. __________________ "If the women don't find you handsome, they should at least find you handy." - The Red Green Show Current Tank Info: 24g BioCube reef