3/4 vs. 1" Return line

[ColdOceanReef]

Hello reefers, I hope all is well. Please stay healthy.

Attached is a diagram of my return line. I am currently running the vectra M1 pump at max flow On 3/4" return line. Though, I am not sure if there any benefits changing the return line from 3/4 to 1". My other concern is the locklines output is only 1/2 . Would there been an issue with the lockline being 1/2 if I change to 1" return line. Any input is greatly appreciate.

 

[dreamcatcherr9]

I’m curious to what the experts will suggest, so I’m following along.

My curiosity, why not stay at 3/4” (not bother with 1”) and drop to 1/2” returns.

Or could you do 1” from pump all the way up?

 

[Joeg]

I'm also interested to see comments from those with more plumbing knowledge will think.

My initial thought is that it's probably not worth the trouble unless you had another reason like adding a manifold to feed other devices. If that were part of the plan then I would bump that bottom section up to 1".

 

[jsker]

#reefsquad some guidance please, there are some better plumbers than I in the squad

 

[Flippers4pups]

1" will provide better flow through the distance than 3/4". Exiting through 1/2" lokline won't effect the flow as it's only at the end.

I've always tried to eliminate 90 degree elbows In the return line and drains, even though some say it doesn't matter. I use 45's when I can.

 

[nereefpat]

Looks like the output of an M1 is 3/4", so I would just go 3/4" the whole way. You might get a little less total dynamic head by increasing to 1", but I'm not sure it would be worth it either.

I'm not a fan of loc line...I'd just let the naked 3/4 " PVC enter the tank.

 

[Albertan22]

You can get about 800 more gallons per hour out of a 1 inch pipe than you can a 3/4 inch.

You will obviously lose some of that benefit when you reduce down to 1/2 inch but as someone else said, the effect is lessened if the reduction is at the end. If you plan to do a manifold then 100% don’t hesitate to do the upgrade. So many people build their manifolds out of pipe that is too small and don’t understand why they can’t get any flow out of them and why their returns suddenly have no flow. All pipes are not created equal.

 

[robbyg]

Putting in some pipe lengths into the drawing would make the answer easier.
Overall assuming the height going up is not extreme I would say your fine, I see no benefit in changing the rest to 1" pipe.

 

[robbyg]

You can get about 800 more gallons per hour out of a 1 inch pipe than you can a 3/4 inch.

You will obviously lose some of that benefit when you reduce down to 1/2 inch but as someone else said, the effect is lessened if the reduction is at the end. If you plan to do a manifold then 100% don’t hesitate to do the upgrade. So many people build their manifolds out of pipe that is too small and don’t understand why they can’t get any flow out of them and why their returns suddenly have no flow. All pipes are not created equal.

With a Vectra M1 and lets say 5 feet of head and those elbows he is lucky if he has 850 GPH of total flow going to those two 1/2" Loclines. Going with 45 degree elbows might give him a slight bit more flow but it would not be worth the effort.

 

[Albertan22]

With a Vectra M1 and lets say 5 feet of head and those elbows he is lucky if he has 850 GPH of total flow going to those two 1/2" Loclines. Going with 45 degree elbows might give him a slight bit more flow but it would not be worth the effort.

Oh I’m not arguing that. It really depends on whether he ever wants a manifold and what kind of head pressure he is dealing with. Those charts don’t account for hydraulic head. If he’s pumping up out of a basement then he should go with bigger pipe to account for head loss, similar for a manifold. Otherwise probably not worth it. Was just trying to give the raw data so he could make his own choice.

 

[ColdOceanReef]

You can get about 800 more gallons per hour out of a 1 inch pipe than you can a 3/4 inch.

This chart is very helpful. Gives me some insight in the tubing sizes. I do not have any manifold, but I think with two 90 elbows on the 3/4 caused pressure lost. That's why, my main drain valve opens only about 40%. I am thinking redo my return lines with 1" silicone tubing. I will keep the same pump for now to see if I need to open the valve further on my drain line. Thank you all.

 

[ca1ore]

M1 doesn't handle back pressure well at all. You'll see material reductions as you move below the 1 1/4" native output on the pump. I cannot say for certain how much flow 3/4" pipe and dual 1/2" locline will 'cost' you, but it will be material. The question really is whether you feel the current flow is adequate. If yes, then don't change it; if no .....

 

[DCR]

That chart is highly misleading except for the gravity flow column. It is intended for spa pumps that operate maybe a few hours a month and can tolerate the power consumption associated with high head losses. The middle column is for 60-100 psig which equates to 140-230 feet of head, which pretty much excludes all return pump systems. It should not be used for aquarium applications.

The 1/2" Loclines and the 3/4" pipe are going to restrict the flow far below the M1 rating. I would be surprised if you are getting much more than 400-500 gph from that set-up. That is why your siphon drain is restricted so much. That flow may be acceptable, but you could use a much smaller pump. If you want more flow, I would increase the 3/4" pipe to 1" and the 1/2" Loclines to 3/4" if possible. It would also allow you to run the M1 at a lower speed and save power.

 

[ColdOceanReef]

.....
The 1/2" Loclines and the 3/4" pipe are going to restrict the flow far below the M1 rating. I would be surprised if you are getting much more than 400-500 gph from that set-up. That is why your siphon drain is restricted so much. That flow may be acceptable, but you could use a much smaller pump. If you want more flow, I would increase the 3/4" pipe to 1" and the 1/2" Loclines to 3/4" if possible. It would also allow you to run the M1 at a lower speed and save power.

I have a 150g SCA and the return line strictly designed thru the overflow. Let said, changing the lokline to 3/4 is a complicated process. Though, you are correct, I am getting about 600 at most on the M1 on my current setup.

 

[nereefpat]

Does the M1 not have a 3/4" output?

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[DCR]

I have a 150g SCA and the return line strictly designed thru the overflow. Let said, changing the lokline to 3/4 is a complicated process. Though, you are correct, I am getting about 600 at most on the M1 on my current setup.

If you have a nozzle on the end of the Locline, you might try removing it. I have heard of people removing them and increasing the flow significantly - especially the flat head type.

 

[ca1ore]

Does the M1 not have a 3/4" output?

The quick connect collar on the output is indeed 3/4" but it was brutal on flow which is why ETM sold the white native adapters.

 

[ColdOceanReef]

If you have a nozzle on the end of the Locline, you might try removing it. I have heard of people removing them and increasing the flow significantly - especially the flat head type.

The method that SCA did on their return line makes it complicate to modify anything. The lokline threaded thru the overflow to keep the pipe steady. Therefore, I need to expand Both holes on the overflow to 3/4 and modify the existing pipe to accommodate 3/4 lokline. (See image) so really my option is to change 3/4 below the tank to 1"

 

[DCR]

I understand the difficulty, but I believe those flattened exit pieces on the end of the locline can be removed from the rest of the assembly. This will open them up a lot and give more flow. There was a recent thread on here about someone doing that and it made a significant difference in the flow rate

 

[ColdOceanReef]

So I changed to 1" plumping and the noticed some improvements, but not much. I did actually opened my drain line another turn or so. However, the biggest improvements I saw were pH and ORP.. My pH generally low 7s and ORP at low 200s. After I changed to 1" plumping. PH is now high 7s or low 8s. ORP increased to above 350. So I decided to go with a bigger pump in 3000g/h hope to get more flow and air exchange.

Best regards