Help! What am I doing wrong? Air in overflow pipe

[frootloops]

Hi all, I'm almost finished building my tank and was testing the plumbing before I finalize it.

My problem is this. I have 4 pieces of 1" pipes to serve as overflows on one side of the tank.

My pump is rated for around 900gph at 5' of head. I originally planned on getting another pump that's rated at around 1200gph for a total of around 2000 gph for the two pumps.

To see if my overflows could handle the volume, I ran the 900GPH pump alone. I closed 2 of the overflow pipes to see if 2 pipes could handle the water volume. To my surprise, the tank water began to rise and the overflow just couldn't keep up. I had to open a third overflow pipe to prevent a flood.

(These are the pipes connected to the overflows above)

(This is the sump. Water from the 4 overflows collects here)

(Return pipe of the 900GPH pump. Plugged the other one. That's where the other pump is supposed to go. If I could fix my overflow problem)

I used a calculator on another site and it told me that one 1" pipe could handle 700GPH. I noticed that I have air in the pipe, that's why it couldn't handle the volume of water.

Anyone knows how to solve this problem? Tank is 380 gallons and I don't think 900GPH is enough to filter the tank.. Or is it?

 

[scottswald]

i dont know much about the topic but im curious as to why you went for 4 inch o/f's as opposed to say 2 x 1 and 1/4 ' pipes?

 

[knobhill]

Hi all, I'm almost finished building my tank and was testing the plumbing before I finalize it.

My problem is this. I have 4 pieces of 1" pipes to serve as overflows on one side of the tank.

My pump is rated for around 900gph at 5' of head. I originally planned on getting another pump that's rated at around 1200gph for a total of around 2000 gph for the two pumps.

To see if my overflows could handle the volume, I ran the 900GPH pump alone. I closed 2 of the overflow pipes to see if 2 pipes could handle the water volume. To my surprise, the tank water began to rise and the overflow just couldn't keep up. I had to open a third overflow pipe to prevent a flood.

(These are the pipes connected to the overflows above)

(This is the sump. Water from the 4 overflows collects here)

(Return pipe of the 900GPH pump. Plugged the other one. That's where the other pump is supposed to go. If I could fix my overflow problem)

I used a calculator on another site and it told me that one 1" pipe could handle 700GPH. I noticed that I have air in the pipe, that's why it couldn't handle the volume of water.

Anyone knows how to solve this problem? Tank is 380 gallons and I don't think 900GPH is enough to filter the tank.. Or is it?

Your overflows are too small...they should have been 1.5". Is your return line 1" as well?

Also, a 2.5 turnover rate isn't enough unless you have a very small bioload (which most MFKers never do!)

There really aren't any perfect overflows that will entirely gulp down water and not air. Because you used 90 degree angles on the overflows, it is also creating a back pressure which impedes the path of the water.

You may have to go back to the drawing board on this one unless a super genius has a brilliant engineering solution...

 

[MATTCB]

are the pipes that you have running horizontal with elbows in pic #2 level? They should running down hill ever so slightly, you may air trapped in the one of the elbows if it is going up hill. How did you figure you have air in the pipe?

 

[frootloops]

Well I originally planned on installing two 1.5" - 2" overflows but the largest diameter stainless steel pipe I was able to find was 1", that's why I installed 4 of them.

 

[frootloops]

Is your return line 1" as well?

return pipe is 3/4". I don't think the diameter of the return line is significant

 

[MATTCB]

Your overflows are too small...they should have been 1.5". Is your return line 1" as well?

Also, a 2.5 turnover rate isn't enough unless you have a very small bioload (which most MFKers never do!)

There really aren't any perfect overflows that will entirely gulp down water and not air. Because you used 90 degree angles on the overflows, it is also creating a back pressure which impedes the path of the water.

You may have to go back to the drawing board on this one unless a super genius has a brilliant engineering solution...

I dont think the overflows are to small, I run a 6000gph pump (about 4500-5000 @the tank) with 3 x 2" pipes with no problem.

You are correct about the turn over rate, it needs to be way higher.

 

[MATTCB]

return pipe is 3/4". I don't think the diameter of the return line is significant

what pump is this for? 3/4" may be right

 

[frootloops]

are the pipes that you have running horizontal with elbows in pic #2 level? They should running down hill ever so slightly, you may air trapped in the one of the elbows if it is going up hill. How did you figure you have air in the pipe?

The pipes are angled slightly downwards as it heads towards the sump.

When the 2 overflows were running at full capacity, I checked the end of the overflow pipes to see how much water was flowing out. Turns out that only about 1/3 to 1/2 of the capacity of the pipe was being used. I also checked the inlet of the overflows and I saw that a void was present in the middle of the pipe.

(Pump running)

(pipe starting to fill)

(pipe at full capacity)

(End of 2 pipes at MAX capacity)

In the last pic, I only opened 2 overflows and the water level in the was rising fast. As you can see, the water coming out of the overflow is pretty unimpressive

 

[frootloops]

what pump is this for? 3/4" may be right

That's for the 900GPH pump