Damaged Sand Filter Laterals

[denniswiseman]

Hi

After replacing my laterals because of filter media coming back into the pool. I was wondering if anyone had an idea as to how they got damaged
The only solution I can come up with is that when backwashing the area below the lateral becomes a void and then allows the weight to push down

 

[duraleigh]

No reason for area underneath laterals to be voided. My bet would be a heavy dump of sand while the filter was empty of water (initial fill or refill)

 

[denniswiseman]

No reason for area underneath laterals to be voided. My bet would be a heavy dump of sand while the filter was empty of water (initial fill or refill)

That wasn't the case as I had water in and the media went in slowly

 

[JamesW]

How old is the filter. If it's really old, they might just be worn out. Not common, but possible.

If the multiport is switched while the pump is on, the laterals can experience "water hammer".

 

[denniswiseman]

How old is the filter. If it's really old, they might just be worn out. Not common, but possible.

If the multiport is switched while the pump is on, the laterals can experience "water hammer".

Probably about 5 years
I haven’t switched the MPV with the pump running
There were more broken and bent laterals
I was just concerned how the damage occurred

 

[JamesW]

So, it worked fine for 5 years and then suddenly it begins to pour sand into the pool?

 

[denniswiseman]

So, it worked fine for 5 years and then suddenly it begins to pour sand into the pool?

That’s about right

 

[JamesW]

Do you have a picture of the system?

What pump and filter do you have (make model)?

Is the multiport plumbed correctly?

Was the system run on backwash for a long time or while vacuuming to waste?

 

[denniswiseman]

Do you have a picture of the system?

What pump and filter do you have (make model)?

Is the multiport plumbed correctly?

Was the system run on backwash for a long time or while vacuuming to waste?

Most of the info is in my signature but the pump model is 81004 which is a 0.37kw which equates to about 0.5 hp
The MPV is piped correctly and hasn't been run for long periods on backwash and if it went to waste it would by pass the filter
When I run on recirculate or bypass there was no media returning to the pool
My pool is piped correctly and I was just seeing if anyone on the forum had an idea as to why there was a dramatic failure of these laterals

 

[Costas > DownUnder]

A bit hard to 100% conclude from the photo but I note some possible discolouration of the plastic material or were they like that from new?

Could it be that the plastic has been weakend over time (become brittle) thereby allowing the laterals to break?

This would explain the multiple failures.

 

[denniswiseman]

A bit hard to 100% conclude from the photo but I note some possible discolouration of the plastic material or were they like that from new?

Could it be that the plastic has been weakend over time (become brittle) thereby allowing the laterals to break?

This would explain the multiple failures.

You are correct about the discolouration of the plastic and they weren't like that from new but I can remove the discolouration with my fingernail
The failure is at the exact same spot on all of them, some have shown signs of being bent at the failure point but haven't failed yet
All the laterals are straight except for the failure where they meet the screwed portion
I was just hoping someone would have had the same experience. I shall put it down to experience and if someone else has the same problem they may have the answer

 

[JamesW]

There are multiple reasons why laterals break. That's why I asked the question.

Even if someone else has dealt with broken laterals, the reason for their damage might not be the same as the reason for yours.

If they are all bent down, the sand dump seems the most likely answer.

If they are not all pointing down, then I would suspect that the multiport got moved with the pump on.