Bottom drains loose suction over time? (Gravity fed system)

[MD56]

Hi all,

We recently bought a house with a largish (2k gallon pond). The pond has no fish currently so I'm taking the opportunity to learn / experiment with the setup so I can become familiar.

The pond has 3 x 2.5" bottom drains which feed into the first of 4 filtration cells which are in the ground beneath our deck.

From what I can tell, the drains are totally gravity based. As water leaves the first cell it is refilled through the bottom drains

So here is the issues i'm having, the drains seem to have veeerrry little suction. So little that I can float a leaf over them and nothing really happens. The leaf will eventually fall into the drain but not with any kind of real pull.

Is this normal?

Just for grins once I plugged the drains, emptied the water out of the first cell and then pulled the plugs that were covering the drains. Water came pouring in from the bottom drains and filled the cell verry quickly. After that, I noticed the drains seem to have some noticeable suction (even after the cell was filled). Again though, over time though the suction diminished again.

 

[Dave 54]

I think this will happen the bottom drain doesnt really come into itself until you switch the pump on , , I find it strange though the builder chose that bore of pipe all the bottom drains I've ever come across in the UK are 4"

Dave

 

[MD56]

Hi Dave,

The pump is always running, but all the pump is doing is returning water from the last filtration cell back to the pond. Gravity is what feeds the water from the pond into the filtration system.

 

[HARO]

Just out of curiosity, is the pond full? When you say you can float a leaf over the drain, I get the impression your water level is very low. This would greatly reduce the effectiveness of a bottom drain. The drain HAS no 'suction', it is the weight of the water column that pushes water (and waste) down the drains.
John

 

[MD56]

Hi, yes the pond is very much full (aprox 4ft deep). What I should have said is that I can take a rake stir up some of the leaves other debris on the bottom... it will float right past the drain without being vicariously sucked in.

I guess I just assumed the drain would have more a vacuum effect.

 

[HARO]

If it was me, I'd get a (new) plumber's snake and run it through those pipes.
John

 

[DoDad]

those BD's are to small. The minimum should be 3"

 

[Mucky_Waters]

How about posting some pictures of your pond and filter system???