Suddenly, my Eshopps PF-1200 overflow box has suddenly developed a problem...

[Dom]

So I have an Eshopps PF-1200 overflow box running on a new build.

Previously, this same box worked on a 90 gallon without issue and is currently installed on a 125.

The issue is that there appears to be a huge amount of turbulence where water flows into the internal box. As water travels through the twin tubes, air bubbles are picked up.

Over time, the air bubbles become trapped in the tube. Eventually the bubble becomes so big that the siphon is broken.

I've been running it on one tube for the last 24 hours without issue. I'm guessing that is because when bubbles come out of the single tube, there isn't a second tube for them to go up. The bubbles come out of the single tube and continue on their way.

Why would this suddenly become a problem?

Dom

 

[Dom]

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[vlangel]

I have always used an Eshopps overflow box. They work great if the flow going through them matches the return pump flow (taking in consideration loss of flow due to head pressure).
It sounds like the return pump was not pumping enough flow using both U tubes. However when you went down to one U tube that was enough flow to keep air bubbles from building up.
If you want to use both U tubes, probably a bigger return pump ( preferably a variable speed to dial in the flow exactly) will fix the bubble build up problem. Make sure your drain, plumbing and sump can handle the added flow however.

 

[Dom]

I have always used an Eshopps overflow box. They work great if the flow going through them matches the return pump flow (taking in consideration loss of flow due to head pressure).
It sounds like the return pump was not pumping enough flow using both U tubes. However when you went down to one U tube that was enough flow to keep air bubbles from building up.
If you want to use both U tubes, probably a bigger return pump ( preferably a variable speed to dial in the flow exactly) will fix the bubble build up problem. Make sure your drain, plumbing and sump can handle the added flow however.

@vlangel

Hello and thank you for the response.

What is so puzzling is that the same return pump and overflow were installed on an old 90 using both tubes without issue.

 

[vlangel]

@vlangel

Hello and thank you for the response.

What is so puzzling is that the same return pump and overflow were installed on an old 90 using both tubes without issue.

Hhmm, that is puzzling. Is it possible that in the new build the head pressure is greater thus the flow is lower through the U tubes? Even a 6" increase in height from the return pump to the return nozzle could change the flow. It does not take much for the bubble build up to happen.

 

[Dom]

Hhmm, that is puzzling. Is it possible that in the new build the head pressure is greater thus the flow is lower through the U tubes? Even a 6" increase in height from the return pump to the return nozzle could change the flow. It does not take much for the bubble build up to happen.

BINGO!

That MUST be it; head height.

The new build has added 10" to the head height. Do you think that is enough to significantly slow flow?

 

[vlangel]

BINGO!

That MUST be it; head height.

The new build has added 10" to the head height. Do you think that is enough to significantly slow flow?

I definitely think that could be a possibility. I remember looking at my basement sump and for every foot of height the flow went down significantly.
You may need to move the pump higher or buy a pump that has more flow capacity.

 

[Dom]

I definitely think that could be a possibility. I remember looking at my basement sump and for every foot of height the flow went down significantly.
You may need to move the pump higher or buy a pump that has more flow capacity.

So after watching it a bit, I think I have a pretty good idea of what's happening, but I don't know what conclusion to draw.

The overflow has two sections connected by the U-tubes; the one on the interior of the tank, I will call the "wet side". And the section on the outside, I'll call the "dry side".

Bubbles travel from the wet side to the dry side. And over time, those bubbles build up and break the siphon.

Initially, I thought those bubbles were the result of turbulent water in the wet side. But what I actually think is that the water level on the wet side is such that the tubes are just below the water line. The flow coming into the box is sometimes causing the tube to "slurp". It is during this slurping that are is getting sucked in to the tube.

So for me, the question becomes; how to I get the U-tubes further below the water line?

I've tried lowering the wet side deeper into the water line, but that doesn't really help as the U-tubes are fixed height.

 

[vlangel]

So after watching it a bit, I think I have a pretty good idea of what's happening, but I don't know what conclusion to draw.

The overflow has two sections connected by the U-tubes; the one on the interior of the tank, I will call the "wet side". And the section on the outside, I'll call the "dry side".

Bubbles travel from the wet side to the dry side. And over time, those bubbles build up and break the siphon.

Initially, I thought those bubbles were the result of turbulent water in the wet side. But what I actually think is that the water level on the wet side is such that the tubes are just below the water line. The flow coming into the box is sometimes causing the tube to "slurp". It is during this slurping that are is getting sucked in to the tube.

So for me, the question becomes; how to I get the U-tubes further below the water line?

I've tried lowering the wet side deeper into the water line, but that doesn't really help as the U-tubes are fixed height.

Is it possible that you have the U tube backwards? Mine are not perfectly symmetrical.

 

[chipmunkofdoom2]

How much flow is your return pump providing?

I've used overflow boxes for almost two decades, both on my personal tanks and on tanks at the National Aquarium when I worked there. Bubbles always get into the U tube. There's no easy way to prevent that. What you can do is make sure you have enough flow going through the box so that the bubbles can't build up.

 

[Dom]

I definitely think that could be a possibility. I remember looking at my basement sump and for every foot of height the flow went down significantly.
You may need to move the pump higher or buy a pump that has more flow capacity.

UPDATE:

Okay, so the issue was definitely related to excessive flow through the box.
I took the sponge filters that fit over the drain tubes located in the outer portion of the box out.

This allowed for flow rate to increase and create turbulence in the in-tank skimmer portion. This caused air to get sucked into the u-tubes, breaking the siphon.

Thank. you again for the help!

 

[Slocke]

Is it possible that you have the U tube backwards? Mine are not perfectly symmetrical.

Interesting. I'm having the issue that whenever the return pump is off one of the U-tubes drains. I wonder if this is why?

 

[Dom]

Interesting. I'm having the issue that whenever the return pump is off one of the U-tubes drains. I wonder if this is why?

That isn't quite the same issue I was having.

I lose siphon in one of the tubes as air bubbles from turbulence collect at the apex of the tube.

But as I mentioned in the update, slowing down the flow by putting the sponge covers back over the drain tubes in the exterior portion of the box has slowed the flow, making it less turbulent.

This resulted in no air bubbles and the problem is solved.

 

[Clarkjw2002]

Interesting. I'm having the issue that whenever the return pump is off one of the U-tubes drains. I wonder if this is why?

Check the U tubes for small cracks.

I just got around to cleaning a double lifereef overflow I bought here a year or so ago. 2 of the 6 U tubes were cracked. It wasn't readily apparent but when I filled with water and held upside down I could see a slow leak develop. These were the cleanest two so suspect he had problems with them prior to sale.

Easy way to check is to fill a container with a few inches of water, submerge the tube, then stand up full of water and leave standing overnight. if the water is drained you have a crack somewhere.

As an aside, am I the only one that actually cleans equipment and reports issues before selling here?

 

[Slocke]

That isn't quite the same issue I was having.

I lose siphon in one of the tubes as air bubbles from turbulence collect at the apex of the tube.

But as I mentioned in the update, slowing down the flow by putting the sponge covers back over the drain tubes in the exterior portion of the box has slowed the flow, making it less turbulent.

This resulted in no air bubbles and the problem is solved.

Check the U tubes for small cracks.

I just got around to cleaning a double lifereef overflow I bought here a year or so ago. 2 of the 6 U tubes were cracked. It wasn't readily apparent but when I filled with water and held upside down I could see a slow leak develop. These were the cleanest two so suspect he had problems with them prior to sale.

Easy way to check is to fill a container with a few inches of water, submerge the tube, then stand up full of water and leave standing overnight. if the water is drained you have a crack somewhere.

As an aside, am I the only one that actually cleans equipment and reports issues before selling here?

Thanks!
I hope it is not broken as it is brand new. I have 2 PF-1000 and 3 of the 4 U-tubes work fine. What I thought was happening was that it was shorter than the other and that when the level got too low it was draining but I guess it could be either the bubble issue or a crack.

 

[Dom]

UPDATE:

So the issues just keep coming with this overflow. This is surprising as it worked perfectly on its previous tank.

NOW, I have something going on where an air bubble gets trapped in the drain line. Eventually, it gets pushed out into the sump with a big "GLUB" sound.

Eventually, I will drill this tank. But since I haven't decided on its permanent spot, I decided to wait until and use this external overflow.

 

[Slocke]

UPDATE:

So the issues just keep coming with this overflow. This is surprising as it worked perfectly on its previous tank.

NOW, I have something going on where an air bubble gets trapped in the drain line. Eventually, it gets pushed out into the sump with a big "GLUB" sound.

Eventually, I will drill this tank. But since I haven't decided on its permanent spot, I decided to wait until and use this external overflow.

Happening to me too. It doesn't seem to cause any mechanical problems but it is so loud. I turned down the return pump and that stopped it but now my flow rate is lower than wanted.

 

[Dom]

Happening to me too. It doesn't seem to cause any mechanical problems but it is so loud. I turned down the return pump and that stopped it but now my flow rate is lower than wanted.

My drain line has (2) 90 degree turns. I may try using (1) 45 degree for a more direct path to the sump.

I was also thinking about going with soft tubing on the drain lines to make the flow more smooth.

 

[Slocke]

Unfortunately that sounds like what I already have:

 

[Dom]

Unfortunately that sounds like what I already have:View attachment 2984787

Yes, but you are using 90 degree PVC connections. My idea is to connect 2 barb fittings to the bulkheads in the box and then just run the hoses to the sump. I'm hoping the gradual turns to the sump will allow smoother and less turbulent flow.