Return pump, Loc-lines, or Flare Fitting? Which one is my issue?

[LMDAVE]

I have question about my return flow and turnover through the sump on a new build. I have a Varios 6 pump, which is rated for 1700+ GPH, however I understand with 90 deg elbows and head height (about 4 ft) the number is going to go lower. When I was setting up my system I was asked if I was going to increase the stock loc lines from 1/2" to 3/4", which would require me drilling the overflow outlet at the weir bigger, so I stayed with 1/2". There's a 1" line leaving the pump and tee's off to two 1/2" loc lines. I was curious what my "actual" flow was so the only thing I could think to do was stick the outlet of the loc line into a gallon jug and time it.

It was about 30 sec to fill the jug. So, that's 2 gal/min, or 120 GPH * 2 loc lines = 240 GPH. My tank's actual gallons is probably in the 80 something range so I'm looking at 3x turnover. My Various 6 pump is on 4 out of 5 on speed. When I raise it to 5, there is no change, so my guess is the restriction is the loc lines? Or maybe the Flare fitting on the end of the lines? It's probably has a lower cross-sectional area than a 1/2 circle.

I feel my return pump probably has a lot of power and pressure, which will run my future manifold with no problem. But, I would like to have the option of have a little more tank turnover than 3x.

Any ideas where the issue is?

Pump?
Loc line size?
or flare fitting on the end?

 

[RobZilla04]

When you say there is "no change" when going from 4 to 5 on the return pump speed, there is no change in your test bucket or no change in the water level in the sump?

I suggest re-running the test with the return set to 5. Run it twice, once for each lock line outlet. On occasion one may have more flow than the other.

 

[LMDAVE]

Yeah, no change on output when going from 4 to 5, Still 30 sec per gallon (checked on both sides also). When I drop down to 3, there's a change (lower flow obviously, but seems max out at 4). So, I'm leaning towards it being the 1/2 loc line or the flare nozzle. When I get home today I'll get an exact measurement of the nozzle output, but from memory its a rectangle probably about 3/16" x 1", so maybe I just need a different nozzle like just a 1/2" round.

 

[ca1ore]

I think the assumption that the varios pump has 'a lot of power and pressure' is a flawed one lol. Other than the German pumps with absurd price tags, none of the current crop of DC pumps handle pressure well at all. Expecting a native 1 1/4" output pump to perform well through dual 1/2" locline is your issue. Flow area of dual 1/2" is only about one third of the flow area of a single 1 1/4" so that is putting massive back pressure on a pump ill designed to handle it.

 

[DCR]

Anything 1/2" is going to be a severe restriction. I would first get rid of the flare as they are very restrictive. Just leave it open ended. That might be adequate for your needs. Next step up would be to increase the returns from 1/2" to 3/4". Ideally should really have 1" all the way or as close as possible to the bulk head. If you do that, I think you might get as much as 700 gph. Changing the pump is not going to significantly improve anything unless you were to go with some very high head pump (30+ feed of head). This is large Iwaki/Pan World territory.

 

[LMDAVE]

@ca1ore I'm sorry but that doesn't quite make sense, are you saying that this pump is garbage and cant put out what it says, or are you saying pushing the pump through 1/2" loc lines is the issue? If the issues bottle-necking into 1/2 loc lines, then I need a bigger diameter output. The fact that the pump is maxing out at 4 is what what made me think that. I cant find the exact data on what 1/2 inch loc lines can handle. I do think I found one post showing around 400 GPH (which would be more than enough with two lines), so then it made me think it could be the small output of the flare nozzle choking it down. Just wanted some second opinions before tear the loc line down, or boring out a bigger hole in the overflow.

 

[LMDAVE]

Anything 1/2" is going to be a severe restriction. I would first get rid of the flare as they are very restrictive. Just leave it open ended. That might be adequate for your needs. Next step up would be to increase the returns from 1/2" to 3/4". Ideally should really have 1" all the way or as close as possible to the bulk head. If you do that, I think you might get as much as 700 gph. Changing the pump is not going to significantly improve anything unless you were to go with some very high head pump (30+ feed of head). This is large Iwaki/Pan World territory.

That's what I'm leaning towards. I really don't care about the spread the nozzle creates, I just want the flow. This is my first sump system and first time using loc-lines, not sure how easy the nozzle pops off without the special tool.

Oh, an it is 1" all the way through the bulk head and overflow, and Tee, there are reducers down to 1/2" FPT right by the weir on each side.

 

[Water Dog]

@ca1ore is not wrong about the poor head pressure characteristics of DC pumps. As an example, take a look at this thread...

https://www.reef2reef.com/threads/a...t-250gph-with-a-vectra-s1-return-pump.481957/

 

[laverda]

The lock line is the issue. Even 3/4” will be restricting the flow some although it will be much better. The shape of lock line is like having a bunch of fittings in the line and every fitting is a restriction.

 

[Sarah24!]

Hello,

Dc pumps have advantages, easier, quiet, reliable (both are really) but they do not have the capacity to manage pressure beyond a min-medium level. Now I’m not saying the various pump is bad, but how your setting it up is.

Not to get all nerd like but simple physics shows us how to obtain the amount of flow and head pressure we need. Follow these formulas, and realize that you must calculate anything between starting point, and ending point. For example, on my 240 I used one dc pump per overflow. I did a direct connect from the pump to the tank. I didn’t adjust the size at all, and my pumps run maybe 45%. If I turn them up much higher my overflows can’t keep up.

Remember those days in high school being bored in class going when will I ever use this stuff. Lol today may be one of them.

Edit yes as others mentioned loc lines severely restrict flow. Keep it simple and straight. My Sump is set where my return lines one has a direct straight path. The second has some slight bends, but when I did the math soft flex hose for return line only, had better results.

 

[doughboy]

loc line is a flow killer.
I started using loc line, then eventually removed them and just used plain old 90 degree elbow at the overflow output. I am able to get the same water level in overflow box with herbie at a lot lower DC return pump setting without the loc lines.

try replacing the loc line with an elbow and do your gallon test again.

 

[LMDAVE]

Woah! I just got home and removed the flare fitting and I got my answer. I have too much flow now! I had to reduce the pump down to 1, then bump it up to 2 and closed the shut off valve in the return line some. I may actually go back to a smaller fitting at the end now. But this pump is way powerful and 1/2” lines are plenty, it was definitely the flare fitting. Trying to balance the system again now. But guess i got my answer.

And my water level raised up about a 1/2 over the weir, it was barely over it before

 

[ca1ore]

@ca1ore I'm sorry but that doesn't quite make sense, are you saying that this pump is garbage and cant put out what it says, or are you saying pushing the pump through 1/2" loc lines is the issue?

Well I see you have found your problem so that’s good. For the record, what I was saying is that the majority of the current crop of DC pumps are optmized for flow over pressure. They’re not garbage, but they don’t handle back pressure well because they were not designed to. Once you start adding back pressure, whether constructed plumbing, locline or flares, you start to lose the energy efficiency advantages.

 

[LMDAVE]

Well seeing these fittings now you can see how much it was restricting even 1/2” lines