How To Fix A Floating Pool Liner
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A floating pool liner can be very unsettling to pool owners who have not witnessed this problem before. There are a few different reason why this problem can happen but the repair process is the same regardless of how it came to be - to fix a floating pool liner you simply need to get the water out from behind the liner...somehow. Before you can get the water out from behind the liner you first need to understand what went wrong that would allow this problem in the first place.
Water behind the liner can really only be from one of two sources which are water leaking out of the pool, or ground water from the water table of the ground surrounding the pool. This sounds easy enough to determine but unfortunately it is not always that easy. Ground water can be the source of a floating pool liner even if you have owned your pool for many years and this has never happened before. Ground water tables can change over time as land around your property gets developed. You can also experience events with elevated ground water tables due to heavy rains, snow melt and even extended periods of drought followed by moderate rains as this changes the speed and ability for the earth to absorb water. The problem does not even necessarily need to be in your immediate area as there can be a cumulative trickle down effect if conditions are just right (wrong).
So how would you know what the source of the water under your liner is? Well, the first thing that we need to note is what is the water level in the pool currently. This one factor will very likely be the key to figuring out where the water under your liner is coming from...but not always. Also, I suppose you could check the water behind your liner for chlorine with a test strip if you have the ability to test that water specifically. Obviously if you have a puddle in your yard that happens to have 3 parts per million of free chlorine we can be fairly certain that it came from your pool. Failing this level of simplicity then you need to look closer at the symptoms of a leaking pool.
Symptoms Of Leaking Pools
If you have a floating pool liner the first symptom that I want to know about is the height of the water level in your pool. However even before this we need to qualify the status of your pool leading up to this event. Have you just opened up your pool for the season or has your pool been running along normally right up until you find your liner floating? Most commonly, by far, vinyl pool owners open their pool in the spring to discover this problem.
Just opened for the spring - The water level in your pool can be affected by the cover system that you are using. Starting with a tarp and waterbag cover, assuming that the cover does not have any holes in it, the water level in your pool will be displaced by the water that was on top of the cover. When you pump off the cover this is effectively lowering the water level in your pool so it is normal to have a low water level when you open a tarp and waterbag pool. A safety cover pool which allows water into the pool will almost always be full to the top if not overflowing by the time you remove it in the spring. If you open a safety cover pool and find that the water level is low then I would consider this a red flag for a problem with leaks in the liner somewhere. If you are here reading about how to fix a floating pool liner and you have just removed a mesh safety cover to find a low water level then these symptoms very strongly point towards a leak in the liner somewhere allowing water to escape the pool. The exact height of the water level in your pool is your next biggest clue as to where you should be inspecting for leaks in the liner.
Pool has been running fine until now - If your pool was running fine until now but you have suddenly discovered that your liner is floating then you need to mark the current height of your water level on the face of the skimmer faceplate with a pencil. It is possible that your pool has been leaking but you have just not noticed yet. Now is the time to start paying close attention. If you have an automatic water filler be sure to turn it off so you can get an accurate reading on how fast your water level is dropping in the pool. The bucket test would be the ideal way to determine if the rate of water loss in your pool matches what the rate of evaporation is or not. If your pool is actively leaking and your liner is floating then you need to find where the water is escaping the liner. You can start this process of elimination with this pool leak detection tutorial.
It is possible that your pool has been leaking and you have not yet noticed so now that you see your liner floating you need to pay especially close attention to your water levels. One method that is often used to help isolate the pool interior surface when a leak is suspected is to plug all returns and skimmer ports with your winterizing plugs for 24 hours. Note your rate of water evaporation in the pool and then refill to the same level again and remove the plugs for 24 hours while recording the rate of water loss. As a final option refill the pool again to the same starting point and run the pump system for 24 hours. The results of these three conditions, and the associated total water loss over a 24 hour period in each state, will almost certainly be able to tell you whether the liner is leaking somewhere in your pool or not.
Your pool should lose the same amount of water over 24 hours in each of these states. The circulation of the water during the 24 hours where the pump is running could conceivably cause an incremental increase in evaporation due to the movement of the water. You should be looking for a difference in water loss of 1/4" or greater. 1/4" of water loss is significant over the surface area of your pool and I consider this to be the smallest unit of measurement you can accurately mark and measure on a moving body of water. If you are out at your pool with a set of vernier calipers then you are looking too hard at the water level...and you are also probably a lot of fun at parties.
Testing the structure of your pool interior surface if you have a main drain on the floor of the deep end will prove difficult. A main drain is hard to plug, for obvious reasons, and there are multiple ways in which a main drain could potentially be leaking. Even though vinyl liner pools do not need a hydrostatic relief valve, many vinyl pools were built including these in the main drain. These mechanical check valves can rust and fail over time, or can become stuck open allowing water to escape your pool. With a vinyl pool the main drain can also have a problem with the screws, flange or gasket which could be leaking - all of which would be exceedingly difficult to determine while the pool is full. Since you can not fully drain a vinyl pool (draining a vinyl pool below 6" of water in the shallow end should never be done) then you simply have no way to isolate the main drain, the hydrostatic relief valve, the flange and gasket, nor the equalizer line or suction line coming off the side of the main drain. For this reason, unless you can swim down and deal with at least plugging the ports on the main drain, you will need to use a process of elimination with the three test states to conclude whether you believe the pool structure to be leaking or not.
High Ground Water Tables Around Pools
When a swimming pool is built there needs to be a great deal of consideration to the ground water table around the pool, and more importantly, how you will usher ground water away from the pool area. Ground water pressure is immensely strong and is the source for all kinds of disastrous pool problems such as concrete or fiberglass pools floating up out of the ground. Vinyl pools are not built in the same way as concrete or fiberglass pools and one of the things that is most significant is the difference in how pools handle ground water.
Concrete pools and fiberglass pools are built to displace ground water completely. For this reason they need to be hydrostatically balanced in the ground. What this means is that there is risk for the pool shell to float and so ground water around the pool is controlled in multiple ways. One method to control the ground water is to install a well point or sump pit with which you can pump water and usher it away from the pool area. If there is any concerns for ground water around your pool then a well point is a very smart move. The other way that concrete and fiberglass pools are protected from pressure from ground water is via a hydrostatic relief valve which is installed in the main drain in the floor of the pool.
A vinyl liner pool is different than fiberglass or concrete pools. Vinyl liner pools use a thin waterproof interior surface which is only attached to the pool "shell" at the flange and gasket connections. A vinyl pool is built using a kit which is essentially wall segments - galvanized steel, resin or fiberglass. The floor is either sand, grout (mortar) or vermiculite concrete over concrete base. No matter how your vinyl pool was built they all have the same feature which is that the shell (walls and floor) are specifically not waterproof.
The way a fiberglass or concrete pool deals with water around it is to use the weight of the water in the pool, combined with a fail-safe hydrostatic relief valve, to oppose the pressure from water pushing upwards on the pool. With a vinyl pool the water surrounding the pool is actually supposed to find its way through the walls and floor specifically so there is no hydrostatic pressure on those features. As a matter of regular operation water actively moves under the liner, and the liner shifts ever so slightly in place from this. Normally this would not result in anything that you would notice in day to day use with the pool. The weight of the water on top of the liner is enough to force any water under the liner out and away from the pool. Only in extremely high water table cases will your liner float enough to notice on the floor of the deep end. If your liner has floated all the way up to the floor of the shallow end then this represents a very high water level and a fairly serious concern for your liner (and your pool).
Drainage Around Swimming Pools
There are a few different ways in which vinyl pools can be built. Some builders install french drains underground to usher ground water away from the pool area. Some builders installing a weeping tile system similar to what you have around the foundation of your home. Some builders use gravity based drainage systems while others use well point or sump pit installations to manually pump away the water as required. Unfortunately many vinyl pool builders give little or no consideration to water tables and the potential long term concerns for water behind your liner.
When a pool is backfilled the choice of material used will determine how much standing water you have around your pool. When 3/4" clear stone is used this will allow a lot of space for which water can occupy. 3/4" clear stone would be suitable for a system where you want water to track and flow easily through the ground such as around a well point or perimeter drainage system. Sand is another common option for backfilling pools, which does allow less physical space for water to occupy (or travel), but can also tend to hold water where other stone aggregate options do not.
There is no short cut to fixing drainage problems around finished swimming pools. In fact, major drainage issues with a finished swimming pool are one of the biggest concerns for a poorly installed pool. Installation of a well point that extends (at minimum) to a foot below the floor of the shallow end is one of the only potential recourses for this type of ground water problem. Even this however may not solve your problem if your pool is installed in clay, hard pan or backfilled with sand or any other aggregate that limits the horizontal movement of water.
If your pool was not built with a well point or sump pit or perimeter drainage or gravity drain system of some kind then you are simply counting on not having a problem with a floating liner. So what happens if your pool does not have any of those features and now you have a problem with a floating liner? If the water is coming from the pool then that will obviously be the first step to fixing this problem. If you have fixed the leak already, or believe the water surrounding your pool to not be water from inside your pool, then you can try to manually pump the water from behind your liner.
For some pools the only thing that is preventing your liner from floating all the time is the weight of the water inside the pool. For this reason if you drain the pool for any reason such as fresh water dilution, or for some kind of service or repair, this is when you can develop a problem with a floating liner. If the water level in your pool has been lowered and this resulted in a floating liner then you should almost certainly fill the pool to operational levels again. This can often resolve the problem on its own. Also worth noting is how you drained the pool. For example, if you drained the pool onto the grass right next to the pool...well...I think we found the problem that caused your floating liner. Any time you drain your pool be sure to drain the water well away from the pool area and preferably to the street drain curbside in front of your house. Lowering the water level in your pool while flooding the area directly adjacent to your pool is a recipe for floating your liner for sure.
Pumping Water From Behind A Pool Liner
If you have a sump pit or well point you should be running that non stop if you have a floating liner. If you have a perimeter drain around the pool that is tied into your pool filtration system (this is rare) then you can use this to draw water from around the pool area and pump it to waste away from the pool area. Failing these convenient features then the only other recourse is to pump water directly from behind the liner. This is an extremely common service call that all pool service companies do especially during the spring when pool water levels are low and ground water tables are high from heavy spring rains and snow melt.
As your liner ages it loses elasticity and taking it out of the coping track becomes harder and harder to do. In order to pump water from behind the liner manually you will need to be able to get a section of liner both out of the track, as well as back in after you are finished pumping the water behind the liner. Boiling water poured onto the track and liner around the area you intend to work is the standard trade secret for helping to manipulate your liner in and out of the track. The lower the water level in your pool the easier it will be since this will give you more vinyl exposed above the water level which means more physical area to stretch the liner.
You will need about 6" to 18" of liner out of the track in order to sleeve a pump suction pipe behind the liner. Some liners can tend to "run" and once you pull them from the coping track the liner can tend to pull out in both direction from where you are working. To limit the amount of running the liner bead does you can use either liner lock or simply a tapered wood clothes peg (with spring removed) to help wedge the liner in the track on either side of the area you are working with. Once you have the liner out of the track you can sleeve a suction pipe from a service pump (or even your own pool pump if you are handy and want to fix this yourself) and then pump the water either into the pool or to a location far removed from your pool area.
Does this process fix the problem of a floating liner? Actually, sometimes, yes it does. Many pools seem to develop this problem over the winter when the water level in the pool has been lowered for winterizing. This results in a service call to pump behind the liner in the spring and reseat the liner, after which the pool operates for the year without any floating. While not ideal, if the pool was built with no other method to control the ground water surrounding the pool then this will be your only option. Assuming the pool itself is not leaking, by removing the water from behind the liner while increasing the water level (and weight) inside the liner, you can often get a liner to sit back against the floor. Even though when you pump behind a pool liner you will be limited to going as low as the base of the wall, this is often enough to "fix" the floating liner or help it along enough in the right direction that the weight of the water in your pool will do the rest.
Problems Associated With Floating Pool Liners
When your liner floats there are a number of concerns. The biggest and most important thing is that the flange and gasket systems on your pool skimmer, returns, main drains, lights and stairs are affixed directly to the pool wall structure and will not move even when the liner floats. This puts strain on these connection points and can result in leaks developing, or existing leaks being made worse. The area of greatest concern is usually the bottom flange on in-wall steps as there is not much vertical height of vinyl in between the shallow end floor and the bottom flange. This means that this area of your pool has the least stretch available and the most likely place for a leak or tear in the vinyl to develop. When you drain a vinyl pool (improperly) below the height of the shallow end floor the connection point here at the bottom of the step flange will take the brunt of the damage.
Assuming that you do not have a severe liner floating problem and it appears that your flanges are not in danger, the next biggest concern is how (where) the liner will seat itself as you evacuate the water from behind the liner. When a liner is installed, it is done so on a warm and sunny day and under these conditions, along with the liner being new, it will easily move, sit or stretch as you need in order to place it precisely in the correct spot. Once your liner has floated then you have lost the original positioning of the liner. While the bead remains stationary in the track, and so no lateral movement of the liner will happen at the top of the wall, the coves, corners and slopes of the floor will most likely all shift.
Since your liner is underwater, unlike when it was first installed, you many never be able to put your liner back where it was intended to go. What you are hoping is that the liner did not shift much, but just floated and will sit back where it was before. This is seldom the case. For the most part the liner will end up where it was before however the sharp contours of the slopes will likely not align perfectly as they once did, and you may likely have more cove at the foot of the walls in the shallow end then previously. While unsightly and not ideal, there is little you can do other than manually attempt to place the liner as the water recedes. This is easier said than done since the water recedes slowly as the pump behind the liner runs.
As opposed to standing in place like a heavy pylon you could pick up a couple bags of pool salt and use these as weighted bags to attempt to keep the liner where you want it. The most important area is the shallow end break point, or the point at which your shallow end floor begins to slope down towards the deep end. You will want to, at minimum, attempt to make the liner seat correctly on both sides of the break point (where the shallow end break meets the pool walls). You may also find it helpful to put two or four bags of salt by the pool steps (if you have in-wall steps) again to help seat the liner with minimal stretch and cove in this area.
All good intentions aside it is very common for vinyl pools with a floating liner to end up with wrinkles on the floor and stretch marks under the flanges - especially around the return ports. These are the telltale signs of a pool liner that has floated. Wrinkles in a liner are ugly, they trap debris, they develop a memory and the color will most often wear off on the raised area...but most likely you do not need to immediately replace the liner. Some times you can even minimize wrinkles by manually working them with a plunger underwater. If you can work a wrinkle to the edge of your pool you may be able to lose it in the cove if there is any cove at all in that location. This is a lot tougher than it sounds since the weight of water is immense and you have almost no purchase with which to grab and manipulate the liner...still it is worth a shot.
Wrinkles left on the walls can be dealt with in a similar way but you also have the option of purposefully floating your liner to help reseat them. Certainly you do not want to flood your pool area again such that your whole liner floats, but running a garden hose for a minute behind the wall may help to hydrostatically balance the vinyl momentarily just long enough to seat it in a more desirable, and hopefully wrinkle free, location.
Long Term Risks Of Water Behind Your Liner
If you ended up with a floating liner in your pool due to a one time event like a leak in the pool which has now been repaired then there will likely be little concern for long term damage. Did your liner reseat everywhere without wrinkles, or with very minimal signs of shifting and wrinkles? If so then you are probably in the clear assuming this does not keep happening again and again.
What happens if you are not so lucky and you have constant or recurring problems with water behind your liner? The long term concerns for this problem is that water does extensive damage to swimming pools when it gets where it should not be. For example you can read this article about damage to pools for long term leaks which talks about how specifically water erodes concrete, washes away fill and undermines structural walls and pool decks. All of these things are a concern if you have repeated problems with water behind your liner. If you have a concrete deck around the pool I would imagine it is showing signs of sinking and cracking already, and if you have stone or interlock it probably looks like a funhouse floor - or will within a few years most likely.
In addition to weakening concrete at an advanced rate and washing away the backfill around your pool incrementally over time, there is concern for rusting of your pool walls if you have galvanized steel walls on your pool. Galvanized steel walls are incredibly durable for inground vinyl pools and seldom have I ever encountered structural failures due to rust where entire wall panel sections need to be replaced, though this can happen if the damage from corrosion is bad enough. Chlorinated water is a much greater concern than simply ground water, however ground water can have adverse pH levels or mineral levels that can contribute to advanced rates of corrosion. Steel walls for inground vinyl pools are meant for direct burial however they are not meant for underwater use and if you have standing water behind your pool walls that extend up to the shallow end of your pool or higher, then that is exactly what you have.
If you are reading all of this information to attempt to solve a standing ground water issue behind your vinyl liner pool I would strongly encourage you to seek the advice of a local professional who can inspect your pool installation for deficiencies. I completely understand the need to limit expensive swimming pool service bills however ground water behind your liner is a complex problem with very little you can do that does not involve major work or hardscaping of the property. There is a point to be frugal and a point where you should willingly pay to call an expert to help diagnose the problem and propose potential solutions. I would say that standing water under your liner, especially if this is something that happens regularly, should be inspected by an expert for a second opinion.
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