Filter decreased outflow

[Mayfly]

Hi All my first post here so hope it's in the right forum.

I would appreciate your thoughts please...

My pond is 10 years old and has had the same filter system that is gravity fed back to the pond. All was well until 2 years ago when an unknown Golden Lab decided to go for a swim and punctured the liner. The pond was emptied and repaired and everything has thrived since, in fact better than before.

However the problem I have had since the repair, and I cannot see for the life of me how it can be related, but every so often now the gravity outflow is not sufficient flow wise and if I'm not careful the filter tank will over flow. In other words the inflow/outflow has become unbalanced.

To make sure this has nothing to do with the filter medium requiring cleaning, I have tried with just an empty tank but it still fills up beyond the required depth.

I fitted a ball valve to restrict the inflow which is a good back up, but would like to get to the bottom of the problem - I stress this system worked well for 8 years. I thought maybe it was debris in the outflow pipes but I have back flushed them on a number of occasions and although it does clear sediment out it hasn't sorted the problem.

Before I enlist my husbands help in taking the whole lot apart and cleaning and re-plumbing lot I thought I would ask if anyone has any thoughts on why this is happening or even a possible solution.

TIA
Pam

 

[addy1]

What are the sizes of the pipes you are using, the in going pipe and the out going pipe. Did you change pumps recently?

Usually you need a larger outflow pipe than the inflow pipe

Maybe with the repair you got the pump working better, got rid of clogging somewhere, so now the pipes need to be balanced.

 

[koiguy1969]

going to a bigger output pipe would probably be a good idea if your filter isnt clogging...you might try snaking the return plumbing maybe it has a clogging issue..if buried it may have cracked and is getting clogged with clay, tree root. etc....

 

[DrCase]

A pic of how it exits the filter may be useful

 

[mikeinpgh]

going to a bigger output pipe would probably be a good idea if your filter isnt clogging...you might try snaking the return plumbing maybe it has a clogging issue..if buried it may have cracked and is getting clogged with clay, tree root. etc....

I like the snake idea like Koiguy said. Or even shove a garden hose up the discharge end.
Do you let your filter run all winter? If not something may have climed up there when it was turned off (Possibly). It wouldn't take much to throw it off balance if the in and out pipes are the same size.
And a picture always helps as stated above.
Good luck,
Mike

 

[taherrmann4]

I agree with koiguy. I have a small 1/2" pipe that is fed off my system to a small creek and every 3-4 weeks I have to take a coat hanger and clean out the algae that cuts down the flow. Even if I turn the ball valve on high it will not clear it out. So I shut it off and clean it out and that fixes it for 3-4 weeks.

 

[Mayfly]

Thanks all - I'm in the process of drawing a schematic diagram - I can only think it can be something that's restricting the pipe slightly, some of it is under ground so maybe crushed as I'm not losing water.

The system [as well as the Koi] were inherited and also worked well for 5 years before I took possession. The filter inlet is one and half inches and the out let is 2 x one and half inch pipes so in theory twice the capacity. The pump also runs all year.

 

[addy1]

With the difference in size that points to some sort of obstruction. Can you get to the end and stick something up it like a electric wire fish? See if there is algae or something stuck.