Overflow Sump Flow

[mrbee2828]

Hello everyone, I have a build thread going but I wanted ask for some opinions about my overflow and sump. My build thread is over here http://www.aquariumadvice.com/forums/f20/benjamins-55g-malawi-cichlid-build-166240.html

As you can see I have converted a 10g tank to a wet/dry and constructed a PVC overflow. Everything has been working for several days now even with a solid 1/2 day power outage test for the siphon. However, I don't feel like it's working as well as I would have imagined.

I have a dual .75" pipe merging to a 1.25" pipe. My flow seems to be closer to the trickle side of the scale than the gushing spray side if that makes sense. If I cut the ball valve off, obviously the pipe fills and once I turn it on there seems to be a HUGE rush of water spray out at a high volume.

That's obviously due to the amount of water built up in the piping and being forced out via gravity. My question is, why isn't the siphon doing that on it's own? I would think there would be plenty enough pull from the tank to keep something between my current flow and the gush I get after turning it on. The overflow "box" seems to be about 1/2 full at all times.

Do I not have a big enough return on the tank to make the water pull stronger? I have a 700gph pump pushing water back about 5' and I know height plays a part in reducing that rate. Thoughts?

 

[AquaRick]

Hi Benjamin,

3/4" pipe has a gravity flow rating of 330gph. With bends in the pipe it'll be somewhat less that that. Having dual overflows will still more than cover the flow that your pump is pushing.

The return pump seems a bit under powered. Do you know what time of pump you have? At 5' of head, that 700gph will be greatly reduced. What gph are you aiming for? How thick is the return pipe?

 

[David S]

Hi Benjamin,

3/4" pipe has a gravity flow rating of 330gph. With bends in the pipe it'll be somewhat less that that. Having dual overflows will still more than cover the flow that your pump is pushing.

The return pump seems a bit under powered. Do you know what time of pump you have? At 5' of head, that 700gph will be greatly reduced. What gph are you aiming for? How thick is the return pipe?

3/4" pipe can handle 660gph and 1.25" can handle 1500gph using this site GPM/GPH Flow based on PVC Pipe Size, ie, How much water can flow through Sch 40 Pvc Pipe Size 1/2" 3/4" 1" 1.5" 2" 2.5" 3" 4" 6"

I would definately upgrade the pump, most decent pumps have a valve on them so the flow can be regulated to suit the overflow pipe,remember using dual pipes has its risks if one pipe gets blocked and the flow is too great for the other 1 flooding can occur.

 

[mrbee2828]

I have a Seltz L rated at 740gph. There are 2 3/4" pvcs T'ing into a 1.25" pipe as you can see above. There is only 1 elbow in the overflow and that's at the bottom of the overflow by the spray bar. On the return however, there are several elbows plus the height so I would imagine it is being restricting a good amount.

If I had higher GPH running back to the tank, would the overflow have a higher rate due to more pressure or volume etc or would it be the same flow out of the tank because it can only suck so much per hour?

Right now the pump and flow are matched well so the levels are staying the same, it's just that I would have imagined that the overflow rate would have been much higher given the setup and thus filling up the sump a lot faster causing me to crank the ball vale closed some.

 

[David S]

I have a Seltz L rated at 740gph. There are 2 3/4" pvcs T'ing into a 1.25" pipe as you can see above. There is only 1 elbow in the overflow and that's at the bottom of the overflow by the spray bar. On the return however, there are several elbows plus the height so I would imagine it is being restricting a good amount.

If I had higher GPH running back to the tank, would the overflow have a higher rate due to more pressure or volume etc or would it be the same flow out of the tank because it can only suck so much per hour?

Right now the pump and flow are matched well so the levels are staying the same, it's just that I would have imagined that the overflow rate would have been much higher given the setup and thus filling up the sump a lot faster causing me to crank the ball vale closed some.

the overflow rate is only governed by the flow rate of the pump if pipe sizes are correct.
your overflow can handle 1500gph, so if your pumps flow at the dt is lets say 1200gph then the flow into the sump(without the spray bar,just an open end) will be 1200gph minus any restrictions.You must make sure the spray bar can also handle the correct amount of water flow to stop any back filling occurring

 

[mrbee2828]

the overflow rate is only governed by the flow rate of the pump if pipe sizes are correct.

David, so in a nutshell, if I was retuning twice as much water, I would get more flow out of the tank with my setup correct?

Just to be sure we're on the same page, I have 2 spray bars. There is 1 at the top of the sump and 1 at the top of the tank for the return. The one at the top has holes drilled which kill the siphon after a certain amount falls back into the sump. The one by the sump is currenly only outputting enough water to spray out of about 1/2 the hole I drilled.

 

[David S]

David, so in a nutshell, if I was retuning twice as much water, I would get more flow out of the tank with my setup correct?
yep

Just to be sure we're on the same page, I have 2 spray bars. There is 1 at the top of the sump and 1 at the top of the tank for the return. The one at the top has holes drilled which kill the siphon after a certain amount falls back into the sump. The one by the sump is currenly only outputting enough water to spray out of about 1/2 the hole I drilled.

Your sray bars will restrict the flow,
there is a way to keep an eye on any backing up in the sump pipework by drilling the top of the spray bar pipe,glue a small spout so you can attach a clear air line to it,run the air line up higher than your overflow.If there is any backing up you will see the water rise in the airline.I hope i have explained that enough

 

[mrbee2828]

By backing up, you're saying for example that the overflow is being restricted and by doing this clear air tube I can see the back being pushed out through this? If that's the case, I have tons of holes on the sides of the spray bar not being utilized so I doubt that's the case. I think I need to shoot a video.

 

[David S]

By backing up, you're saying for example that the overflow is being restricted and by doing this clear air tube I can see the back being pushed out through this? If that's the case, I have tons of holes on the sides of the spray bar not being utilized so I doubt that's the case. I think I need to shoot a video.

If you have loads of holes then thats fine,it didnt look too many from the photo,
You just need to upgrade your pump,make sure it has a valve or install one yourself and it'll work fine.

 

[mrbee2828]

Here is a quick clip! Sorry, the first url was bad.

 

[David S]

Here is a quick clip!

http://youtube.com/gDbHgMxqq04

Hmmmm, page not found

 

[AquaRick]

Good call on the 660 gph David. Must have hit the wrong key on the keyboard. **** these small keyboards.

From the vid it seems your pump is a bit weak for what you want it to do. I agree with David and suggest you upgrade the pump and install a pvc ball/gate valve you should be good to go.

 

[mrbee2828]

I think it's worth a shot. I'm going to order a new one tonight and send this one back. I have 3 gate valves installed btw

 

[scottayy]

Okay here's what solved the problem on mine.. though it may not be relevant to yours.

The deeper/fuller the overflow - the faster water flows down (more pressure to push on the siphon). So try raising the water level in your tank to the very top of the overflow skimmer teeth.

And, the faster you pump water back out of the return pump, the faster it fills the main tank, the faster it fills the overflow box.

 

[mrbee2828]

I just ordered a Maxi-Jet 5500 rated at 1,384. I figure my height and elbows are knocking it down a good amount already. I also have ball valves in place if it's too much. However, I'm set up for a 5/8" outlet and this is say s it has a 3/4" or 1". I don't get how it has both but we'll see. If I can do a 3/4" I just need a few feet of 3"4 and a new threaded barb and I'm good to go. I can always drill more holes on the spray bar or take off the end cap if need be.

 

[mrbee2828]

Okay here's what solved the problem on mine.. though it may not be relevant to yours.

The deeper/fuller the overflow - the faster water flows down (more pressure to push on the siphon). So try raising the water level in your tank to the very top of the overflow skimmer teeth.

And, the faster you pump water back out of the return pump, the faster it fills the main tank, the faster it fills the overflow box.

That makes sense. I played with the valves a bit and I think because I had the overflow full throttle and a weaker pump that I was getting a ton of noise. With it dialed down and the water level up a bit it really helped that. I may drill my teeth down some in the pvc and see if I can get more range on my water level as it's REALLY close to the top right now.

 

[AquaRick]

Did you end up cancelling the order for the new pump?

 

[mrbee2828]

Nope I'm going to send this one back when the new one arrives.

 

[Rscomia]

I might be looking at it wrong but are the pipes inside your over flow pointed straight down?

 

[mrbee2828]

They are yes. You can see it in this picture. The go about 1" below the Ts in the prime tubes.