Pool overflow

[guinessnc]

Hi everyone I wanted to get peoples opinion on how deal wit this problem. We have a overflow port on the side of our vinyl pool. We have centipede grass and I’m not really sure if it is the salt content in the water or just the amount of water the centipede is seeing. Centipede does not require a lot of irrigation at all. I hardpiped my backwash line out to the grass as well (nowhere near this overflow output) and the grass does not look like this. FYI, the brown grass is not the issue, centipede goes dormant. I need a solution to the erosion. Any ideas? I was thinking about a cistern or dig out the dirt some lay down weed fabric and put drainage ditch rocks on top to slow the flow. TIA

 

[ajw22]

Can you post some pics around the problem area so we can see your situation?

 

[Auburn02]

Good timing. I just had some drain work done last week and tied my backwash line from the filter to a buried gravel pit, and they Y’d the overflow line into that same line.

Then today I backwashed my filter for the first time and learned that the new path of least resistance during a backwash/rinse is now right back up the overflow pipe into the pool!

So in a nutshell, I need to at the very least have the overflow dissected from the Y, undecided if I will run it on its own line to the same gravel pit or just elsewhere into the yard. Curious to hear where others direct their overflow pipes. I’m on septic so routing to sewer is not an option, and to route to a street gutter would be about impossible due to distance and elevation. I imagine I do not just want to terminate it in the soil a foot underground as the PB intended, but maybe that’s more common than I realize.

 

[guinessnc]

Hi everyone I wanted to get peoples opinion on how deal wit this problem. We have a overflow port on the side of our vinyl pool. We have centipede grass and I’m not really sure if it is the salt content in the water or just the amount of water the centipede is seeing. Centipede does not require a lot of irrigation at all. I hardpiped my backwash line out to the grass as well (nowhere near this overflow output) and the grass does not look like this. FYI, the brown grass is not the issue, centipede goes dormant. I need a solution to the erosion. Any ideas? I was thinking about a cistern or dig out the dirt some lay down weed fabric and put drainage ditch rocks on top to slow the flow. TIA

 

[guinessnc]

Good timing. I just had some drain work done last week and tied my backwash line from the filter to a buried gravel pit, and they Y’d the overflow line into that same line.

Then today I backwashed my filter for the first time and learned that the new path of least resistance during a backwash/rinse is now right back up the overflow pipe into the pool!

So in a nutshell, I need to at the very least have the overflow dissected from the Y, undecided if I will run it on its own line to the same gravel pit or just elsewhere into the yard. Curious to hear where others direct their overflow pipes. I’m on septic so routing to sewer is not an option, and to route to a street gutter would be about impossible due to distance and elevation. I imagine I do not just want to terminate it in the soil a foot underground as the PB intended, but maybe that’s more common than I realize.

yikes! I would freak out if I saw all that dirty water coming back into the pool, especially since we are coming into pollen season. Definitely get the overflow off that backwash line, but if possible have both going to the gravel pit. At the very least keep the backwash on the gravel pit as the force with which that comes out will erode.

Sounds like we live in a similar setup. I am in the country and on septic as well. I am nowhere near the street however we don't have storm drains/sewers/ gutters anyway.

The ONLY possible reason I can think why I am getting erosion on the overflow and not the backwash is that the backwash goes farther out into the yard where the soil was not compacted from pool construction. Majority of our yard is very loamy. The soil around the pool is very hard and compacted.

Can you attach a pic of your gravel pit?

 

[Auburn02]

Can you attach a pic of your gravel pit?

Wish I had one, I had to leave town mid-way through them digging for it and didn't get a chance to take any before I left. It was written up I believe as 60 cubic feet (roughtly 4wx2dx8l), and buried with the top a few inches below grade. They lined the bottom and walls with fabric, filled with the gravel, then wrapped the fabric back over the top before covering with soil. Supposed to be a 4" pipe from the pump/backwash line, then goes up to a 6" pipe where the others (pool overflow and a channel drain on the pool deck) join it before going to the pit. I have no idea if that 6" line just dumps out on top of the gravel or into the middle of it or what, but will ask today when the contractor comes by for me to explain the dilemma.

It will be super easy for them to just dig up the overflow and split it from the main trunk, but then I need to verify that backwashing doesn't then force water back up to the deck drain.

As for your situation now seeing the pic, I wonder if the pool water killed the grass in the first place, then because there is no roots there it's allowing the erosion to happen easily. Is your backwash discharging onto grass also?

I would think compacted soil would lead to less erosion, not more.

 

[guinessnc]

Is your backwash discharging onto grass also?

yes, no erosion, no dead grass. I think I get flow coming out of overflow more often than total water from backwash.

 

[Auburn02]

Interesting. I would just assume that during a normal/moderate rain that the pressure from the overflow would be pretty minimal and thus not likely to cause such erosion but maybe not?

 

[Auburn02]

FWIW, my contractor came by Wednesday - he was shocked just how much the pump put out while backwashing such that the backpressure as it hits and drains into the gravel was pushing water back up the overflow line (and into my deck drain line we determined). So they'll be back maybe today or Monday to split the filter backwash line onto a dedicated run to the gravel pit, leaving the drain and overflow in their existing lines.

Still curious about the OP's issue here.

 

[guinessnc]

FWIW, my contractor came by Wednesday - he was shocked just how much the pump put out while backwashing such that the backpressure as it hits and drains into the gravel was pushing water back up the overflow line (and into my deck drain line we determined). So they'll be back maybe today or Monday to split the filter backwash line onto a dedicated run to the gravel pit, leaving the drain and overflow in their existing lines.

Still curious about the OP's issue here.

Yes backwashing will put a lot of water out. See if you can get a few pics of the gravel pit when they dig it up. Thanks

 

[Auburn02]

Yes backwashing will put a lot of water out. See if you can get a few pics of the gravel pit when they dig it up. Thanks

Well they made the adjustments yesterday, but never really uncovered much so I didn't take any pics, sorry about that. I think this video almost covers it, except they didn't use a section of perforated pipe ahead of the pit (though we might need to change that, more below).

Yesterday after they put the filter waste line on a dedicated PVC all the way to the pit, they only had a 45 degree elbow onto the top of the gravel bed just angled down towards the gravel. Well, I set the filter to backwash and fired up the pump and within about 30-45 seconds we had a nice mudhole forming at the surface. Dumping all that water right at the top at full speed/pressure just wasn't going to cut it. They added about a 4" extension to the 45 degree elbow down into the gravel, I fired it up again, and this time it took about 2.5-3 minutes to start seeing wetness at the surface. They added a longer extension, should be 6-8" down into the gravel now and that should be enough I hope. Typically I never backwash more than a minute anyway so even the 4" was likely enough. But if we run into problems where it's still ponding at the surface, we'll dig up about 8-12' upline from the pit and change that PVC to a perforated pipe in a gravel lined trench to help it relieve some of that pressure before it hits the gravel bed. They may end up just doing that anyway, not sure.