dang sump...
- Thread starter YahooFishKeeper
- Start date
Hey Yahoo,
I'm assuming from this thread that your original set-up was a syphoning type and you are now going to change this to a overflow box with a drain out the bottom of this tank... is this correct?
It sounds to me like your pump is to strong and you are experiancing what is called "Cavitation"(The vacuum created when the discharge capacity of the pump exceeds the replacement in the suction line. This causes bubbling and vibrations that can damage the pump if they occur over an extended period. ) only because you are using a syphon type system it is braking syphon instead of creating air surgise... which is what is going to happen most likely with your new set-up unless you change your drainage pipe size and/or adjust the ball valve on your return pipe.
I ran into this problem on my set-up the first time around and now it's working fine with a few miner adjustments.
I'm assuming from this thread that your original set-up was a syphoning type and you are now going to change this to a overflow box with a drain out the bottom of this tank... is this correct?
It sounds to me like your pump is to strong and you are experiancing what is called "Cavitation"(The vacuum created when the discharge capacity of the pump exceeds the replacement in the suction line. This causes bubbling and vibrations that can damage the pump if they occur over an extended period. ) only because you are using a syphon type system it is braking syphon instead of creating air surgise... which is what is going to happen most likely with your new set-up unless you change your drainage pipe size and/or adjust the ball valve on your return pipe.
I ran into this problem on my set-up the first time around and now it's working fine with a few miner adjustments.
I had a similar problem when I started by overflow/sump setup for my tank. I have setup with a ¾ inch siphon tube that carries the water from the inner to outer overflow box and then outer overflow box (figure 1), is connected to the sump. My return pump is rated at 1,200GPH. At first the siphon was unable to keep the pump … it took less than five minutes to overflow the tank. Someone suggest that I either use bigger siphon tube or another ¾ siphon tube. To my surprise, the water flow rate from the 2 siphon tubes made absolutely no difference, except that every 24 or 36hours the bubbles would get trapped inside the top of the siphon tube and cut off the siphon. Even then my pump was too fast for my siphon. So I placed a valve on the return and slow the return flow.
I ran like this for a month until one day it struck me … I remembered by old college fluid principle called Bernoulli Principles of fluid motion. This law states that the volume of water through various diameter pipes remain the same but the velocity increase with smaller diameter and decrease with larger diameter.
In another word if I had put 3 tubes or just one, the volume of water flowing from inner to outer overflow box remain the same, or if had replaced my 3/4 with 2 inch tube, the flow would still be the same. The critical factor is the height difference in water level between the inner and outer siphon tubes.
I am sure many of you don’t care how it works as long as it works. But I am going to explain to just incase there is one person that is willing to learn. The reason the water flow of the inner to outer overflow box is because the height of the water column in the inner overflow box is greater than the height of the water column in the outer overflow box. Weight of the water column (with depends of gravity) is directional proportional to the height, i.e. higher the height of the water column, heavier it becomes. And always flow in flow gradient (or down hill so to speak).
I another word for me to increase the water flow through the siphon tube, all I need to water make difference in water level greater, or more precisely increase the water in the inner overflow box. How do you do that? Simply by raising the water of the tank. As you raise the water of the tank, more water is poured into the inner overflow box and thus raising the water and creating a greater pressure on that side of the siphon tube than the other … resulting in more water flowing from through the siphon .Since more water is flowing through the siphon tube at faster rate, bubbles that would get into the siphon tube is flushed to the other side and down to the sump, rather than getting trapped at the top of the siphon tube and thus cutting off the siphon. Now I have the return valve opened fully without problem.
Now if you don’t have siphon tube (figure 2), you wouldn’t have to worry about the bubbles and siphon cutting off. But the flow rated to the sump still depend on how much water is poured into the inner overflow box (remember this setup doesn’t have outer overflow box). And the only way to adjust the is increase the water level in the tank and thus more water pouring to the tank. Or you could replace the tubing that run to the sump with a bigger diameter … which would not be productive if have already drilled holes in the tank and hardware all in the place.
Hope this helps.
I am till curious about the new idea.
Rohn.
PS Who said old dog cannot learn new tricks. I am all ready to learn from anyone.
I ran like this for a month until one day it struck me … I remembered by old college fluid principle called Bernoulli Principles of fluid motion. This law states that the volume of water through various diameter pipes remain the same but the velocity increase with smaller diameter and decrease with larger diameter.
In another word if I had put 3 tubes or just one, the volume of water flowing from inner to outer overflow box remain the same, or if had replaced my 3/4 with 2 inch tube, the flow would still be the same. The critical factor is the height difference in water level between the inner and outer siphon tubes.
I am sure many of you don’t care how it works as long as it works. But I am going to explain to just incase there is one person that is willing to learn. The reason the water flow of the inner to outer overflow box is because the height of the water column in the inner overflow box is greater than the height of the water column in the outer overflow box. Weight of the water column (with depends of gravity) is directional proportional to the height, i.e. higher the height of the water column, heavier it becomes. And always flow in flow gradient (or down hill so to speak).
I another word for me to increase the water flow through the siphon tube, all I need to water make difference in water level greater, or more precisely increase the water in the inner overflow box. How do you do that? Simply by raising the water of the tank. As you raise the water of the tank, more water is poured into the inner overflow box and thus raising the water and creating a greater pressure on that side of the siphon tube than the other … resulting in more water flowing from through the siphon .Since more water is flowing through the siphon tube at faster rate, bubbles that would get into the siphon tube is flushed to the other side and down to the sump, rather than getting trapped at the top of the siphon tube and thus cutting off the siphon. Now I have the return valve opened fully without problem.
Now if you don’t have siphon tube (figure 2), you wouldn’t have to worry about the bubbles and siphon cutting off. But the flow rated to the sump still depend on how much water is poured into the inner overflow box (remember this setup doesn’t have outer overflow box). And the only way to adjust the is increase the water level in the tank and thus more water pouring to the tank. Or you could replace the tubing that run to the sump with a bigger diameter … which would not be productive if have already drilled holes in the tank and hardware all in the place.
Hope this helps.
I am till curious about the new idea.
Rohn.
PS Who said old dog cannot learn new tricks. I am all ready to learn from anyone.
Very informative! *celebrate
Probably the best tutorial about returning water from sumps I have read thus far. I’m planning on building one next month so I will be back here for sure.
I do have one question…
What type of overflow box are you guys talking about? Does this same problem happen with Weir standpipe overflow designs as well?
Probably the best tutorial about returning water from sumps I have read thus far. I’m planning on building one next month so I will be back here for sure.
I do have one question…
What type of overflow box are you guys talking about? Does this same problem happen with Weir standpipe overflow designs as well?
