3/4” Lines vs 1/2” lines….

[Thebutcher]

So I went over to HDepot today to pick up the PVC to start the plumbing work on my 75gal.… in normal fashion I ended up standing there looking at the different sizes and got to thinking. Should i do the 3/4” or the 1/2”…. Then i was thinking maybe i should just do the 1”! Then the voice in my head said No… No… the wife would not appreciate the 1” PVC behind the tank. The 3/4” would be more “tolerable”.

So… if i am using a pump that says it will provide 1850 GPH with a 14.8’ max lift would I be better suited going with the 3/4” return lines? Or would i be better off entering in to negotiations with the wife for the 1” lines? I will be splitting the single return line off to a Left and right side returns, there will be 6 elbows, one T-fitting, one Hyroseal Sharkfellow Check valve, one Ball valve and roughly 10 feet of PVC pipe in the mix (Two 24” vertical runs) and about 2’ of PVC hose to the pump.

Any insight would be great and EXTREMELY appreciated!

LMK if you need more info!

 

[BeanAnimal]

To an extent (diminished returns, no pun) are not a problem when upsizing plumbing. Bigger is usually better.

What is the make/model of pump?
What are you using for other flow in the tank (or are you relying on the returns only)

In general

Nominal Size	O.D.	I.D.	Area (sq in)
1/2"	.840	.602	.28
3/4"	1.050	.804	.507
1"	1.315	1.029	.831

As you can see the 1" has almost 70% more area than the 3/4" pipe.

In general, it would be best to come off of the pump with 1" (or larger) for as far as you can and then split off and reduce down to 3/4" for each of the two returns.

 

[BeanAnimal]

I would also NOT use or rely on a check valve

Your sump needs to be able to accommodate the full back flow of the system during a power outage.

If you rely on a check valve, I can assure you that you will have a flood and the wife will not be happy.

(I mean you are going to have a flood no matter what you do... but that will be in addition to the one CAUSED by the check valve).

 

[Thebutcher]

To an extent (diminished returns, no pun) are not a problem when upsizing plumbing. Bigger is usually better.

What is the make/model of pump?
What are you using for other flow in the tank (or are you relying on the returns only)

In general

Nominal Size	O.D.	I.D.	Area (sq in)
1/2"	.840	.602	.28
3/4"	1.050	.804	.507
1"	1.315	1.029	.831

As you can see the 1" has almost 70% more area than the 3/4" pipe.

In general, it would be best to come off of the pump with 1" (or larger) for as far as you can and then split off and reduce down to 3/4" for each of the two returns.

I’ll be using a Current Eflux 6010 pump that I was given and I have two new old stock Ecotech MP40 pumps for the main display area.

I was thinking I would go 1” out of the pump and downsize to 3/4” where the pipes would go vertical on each side of the tank going back up and over the sides?

 

[Thebutcher]

I would also NOT use or rely on a check valve

Your sump needs to be able to accommodate the full back flow of the system during a power outage.

If you rely on a check valve, I can assure you that you will have a flood and the wife will not be happy.

(I mean you are going to have a flood no matter what you do... but that will be in addition to the one CAUSED by the check valve).

I had planned to “balance” the sump volume and set the levels to accommodate the full back flow if the power goes out and have the check valves there as kind of a first line sort of feature. Kind of redundant I guess. The valves would be serviceable units. What do you think?

 

[BeanAnimal]

I think your pipe sizing will be fine given what you have to work with.

I would skip the check valves if possible - they will reduce flow and serve no real useful purpose other than to frustrate you.

 

[Crowed]

check valve have big impact on flow, especialy with low pressure pumps and you can lose 50% or so. even a ball valve have some noticeable impact and is recomended to put one size bigger because internal is more narrow than tube , and check valve put much bigger pressure and they are not realy made for aquarium use.
its not hard to calulate sump volume for back flow. it does not need to be much either, return tube can be near surface or have hole there and then will lose siphon very fast. more water you should have from overflow until it stop flowing down. i would calculate and have a return pump into (last) small chamber so tank can not flood either if overflow stuck, just in case, it should be possible.
if you need to use 3/4 tube, then use them, it will work but have a ball valve on main one.

 

[Vinny Kreyling]

If you are going to downsize,
do it as close to the last fitting as possible.
The general rule of thumb on pumps it to go with the size or larger of the exit, but Never smaller.