Tunnels Under My Pool Liner

by Mark Despain

I have some tunnels that seem to be getting worse under my pool? We are getting ready to replace the liner. What measures should I take to prevent this from happening again?


Hi Mark

Tunnels under the pool liner can be caused by any number of things. Getting the old liner out and examining the pool base would be the first step.

If the tunneling is caused by insects, bugs or ants the method of treatment might just be a good dose of bug killer inside the pool and out. Green Day makes excellent products that when used around the outside of a pool on a regular basis will keep all the little crawling things out from under the pool liner.

If the tunneling is caused by animals like moles the problem is a little more serious. You may find that several layers of black plastic under your sand will take care of the problem. I have known people with recurring mole damage to pour a concrete slab to put the pool on.

You may find something totally different. You may also decide all that needs to be done is the sand base smoothed out again and the new liner installed.

Comments for Tunnels Under My Pool Liner

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Oct 01, 2018
gopher tunnel rut
by: Phil

I've commented on here before as I'd bought a used Secard liner pool back in 2009. Now I have a gopher rut/tunnel underneath the vinyl liner. So it's safe to try to drain the pool to about an inch of water? Can I actually get underneath the liner with that amount of water still in the pool?


The pool will need to be nearly empty depending on how far back you need to pull the liner. Be sure to drain, repair and refill all in the same day if possible.

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Tunnels Under Vinyl Liner Caused by Frogs

by Dan
(West Point, CA)

Our pool is only two years old and the liner is in great shape.

The tunnels started showing up almost immediately and have been getting progressively worse. I figured out that we have tons of frogs and the big ones can do some serious tunneling!

I don't think the liner will tear, but some of the drop offs are almost six inches! Besides being a trip hazard it is really hard to vacuum or brush those canyons!

QUESTION: Any ideas of products to help clean the tunnels? Are there any other options short of removing the liner and redoing the bottom?

I have captured and removed almost 30 frogs, most of them were as big as a softball, and would fill up a baseball cap. I found some exit tunnels and tried a number of things, but nothing seems to work.

Maybe I just have to live with it.

Thank you for any advice you may have, Dan

Hi Dan

I have heard, and seen, of a lot of things that can cause damage under an above ground pool liner, but this is the first I have heard about frogs.

I was called back to a job once to find out why the sand had caved in. It was an area about 3' x 3'. The customer drained the pool, down to about an inch, and we undid the top stuff and pulled the liner back. Underneath the liner was a large group of big fat ants having a field day with their new home. We used some strong ant killer under the liner and around the pool. We redid the sand base, hooked the liner back up and refilled the pool. We never heard from the customer again so that must have worked.

pool drained for repair

The key to working with a liner you plan to reuse is to keep a little water in the bottom. If the liner can be pulled back, and repairs to the base made, and the pool refilled ASAP, it might work. Liners shrink real fast, like as soon as they are dry, so unless you plan to replace the liner do not drain it all the way.

When the time comes that you are OK with changing the liner you may consider these options. To cure gopher problems in Arizona a concrete slab is about the only answer. It is a little expensive but very effective.

The 4 x 8 sheets of Styrofoam work great also. They make a perfect pool base and I do not think frog tunneling would affect them any in the long run.

You have many different options for a new base, when the time comes. For now you may consider this handy device.

Battery Powered Vacuum

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