This is a very rare occurence.
Thorough research indicates they are caused by only two reasons:

1. Hydraulic Flotation (Water getting in behind the liner)
2. Extremes of pH (too high OR too low) can cause wrinkles

(a.) There may be a small hole in the liner. The water will leak through and float the liner. The pool will not leak, but the liner will become 'puffy'

(b.) Water outside the swimming pool walls may rise higher than the water in the pool.

Cascade pools include hydrostatic drainage around the outside wall perimeter to avoid this problem, so check the drain outlet is free flowing and clear of obstacles.

Another thing: In the severe rains we are experiencing, tt may have been overloaded by a sudden downpour (or surface flooding) so call your local Cascade Agent for advice.

The remedy could simply be to lower the pool water and re-tension the liner. It may be necessary to remove some of the pool copings, but often the fix can be affected without doing this.

2. WRINKLES - Also known as "Smileys"

Failure to monitor pH and maintail correct levels is the answer.

Extensive testing by vinyl manufacturers has shown that both very low pH levels or very high levels of chlorine or bromine will initiate excessive water absorption into the vinyl pool liner and lead to liner wrinkles.

Wrinkles that develop in swimming pool liners are caused by the vinyl material absorbing water on the molecular level and thereby changing dimensions (growing).

Low pH and cyanuric acid stabilizer are also factors in wrinkle formation because the activity level of the chlorine is affected by pH and stabilizer level.

Experiments have shown that the use of trichloroisocyanuric acid sanitizer (Trichlor) and low pH levels may cause wrinkling of your vinyl pool liner. Alkaline sanitizers (Hydochlorite) and non-chlorine sanitizer systems have been found to be safer to use with vinyl pool liners.

The growing use of SALT POOLS (electrolysing salts to create sodium hypochlorite) is another problem area, as the chlorine produced has a pH of 11 to 13.

If you are considering using a "Salty" - or already have one, you must regularly monitor the pH or preferrably use a salt unit that checks the pH and adds hydrochloric Acid to correct the pH levels.

NOTE: In New Zealand main cities, due to intense traffic buildup there is the possibility of 'acid rain' and also 'alkaline rain' from the effects of bush fires in Australia poluting the stratosphere coming down in rain, lowering or raising the pH of your pool. You must monitor the pH whenever heavy rainfall has occurred, and make whatever adjustments to the pH are required.

Liner "Growth" will occur on a molecular level when the pool water pH is allowed to either drop to "acidic" levels (ie lower than 3.0) or rise to "alkaline" levels (above pH 12.0) and the normally 'waterproof' vinyl will absorb water - giving the effect of the liner "growing" and "smile shaped" wrinkles forming on the slope of the floor where feet have pushed down on it.

Extreme cases may exhibit such "smileys" all over the floor and walls of the pool.

IMPORTANT NOTE about pH levels
pH is measured on a scale similar to Richter Scale (as in earthquakes) from '0' (ACID) to '14' (ALKALINE). The mid-point or neutral point is too low (acidic) for residential swimming pools, which is recommended to be maintained at 7.6.

Remember that every .1 is TEN TIMES the previous value. 

7.6 is ten times more alkaline than 7.5

"MY pH HAS BEEN ALWAYS BEEN OK - I GET IT CHECKED BY A POOL SHOP"

If you have "Smileys" the pH has been well out of whack. There is NO OTHER reason.

Balance the pool water to avoid pH swings.

Increase Total Alkalinity to 120 by adding Sodium Bicarbonate
Increase the calcium hardness to 200 by adding Calcium Chloride

(Pool shops may have proprietary brands for these products)

If it's a CHLORINE POOL, you may need to check it more often and regularly. An up-to-date Dip Strip (they get past-dated) is the easy answer (although the Chemistry Set we gave you is more reliable). OZONE pools are less likely to suffer from pH swings

- but after heavy rainfall it would be wise to check your pool pH.

Pool water pH can swing rapidy if the pool is not correctly balanced, and the local Pool Shop may not check for the required levels (see above).

Also, if you are using a sterilisation system that creates low pH (i.e. Trichlor Pills, Aquagenie Tablets) or high pH (Salt Chlorinator, liquid chlorine) you may not be aware of the rapid pH "swings" and your test sample may be quite OK at the time you take it in for testing, so Balancing your pool should be a common swimming season" occurrence if you are using these systems.

Pools that use OZONE for sterilisation should never exhibit these issues.

REQUIRED LEVELS  - TO STOP THE pH FROM "SWINGING"

The pH in a "Balanced" pool is buffered (i.e. stopped from rapid change) by the presence of 200 ppm calcium hardness and 120 ppm alkalinity (calcium chloride and sodium bicarbonate). This is called a "Balanced" pool.

HOW TO REMEDY THE "SMILEY" ISSUE

1. Getting a serviceman in with a suction cup device may shift the liner on each side of the 'smiley' and flatten it somewhat, but remember that the vinly has 'grown' due to a chemical imbalance, so this will only be effective if the correct pH levels are monitored!

2. Lowering the pool water to uncover the crease and letting it dry out will usually remove it to recover, however as it means almost completely emptying the pool this needs to be done by a Cascade professional, as Liner re-tensioning will be required.

In a worst case scenario, the liner will have to be replaced ... so AVOID THIS scenario as this is NOT a Warranty issue, and your Insurance will probably NOT cover the replacement either as it is not normally a "sudden occurance" due to a mistake on your part!

Maintain your pool at the suggested 1-2-3-4 regime as noted in your Pool Owner's Manual. For those of you who are unaware of this regime, it is repeated below:

NOTE:
The above phenomenon has occurred with some .50mm Vynide liners manufactured by Aquatech Industries in Auckland.

Since the summer of 2003 all genuine Cascade pools have been supplied with .77mm ABGAL liners from Australia. There have been no reported cases of wrinles appearing in ABGAL liners, but they are not immune to this issue if the pH is not maintained in accordance with the recommended level.

If you pool has been fitted with a replacement liner from a non-genuine Cascade source, it is likely that a Vynide liner has been fitted.

 
The 1-2-3-4 Regime

2. In chlorine pools, maintain active Chlorine Residual at 1.0 ppm (2.0 max)

If your pool has Ozone installed the chlorine level will be much lower or absent  ( .5ppm is fine) Low levels like this may not register on your home Test Kit, and furthermore a Pool Shop may automtically suggest ADDING CHLORINE.

This is NOT CORRECT for an OZONE pool!

REMEMBER TO WINTERISE YOUR POOL IN AUTUMN:

1. Reduce filter hours to 2 - 4 hours (this reduces the Aquagenie chlorinator output)

2. Remove the Pool Cover and store it for winter.

....Leaving it on will increase Algae growth and concentrate what chlorine is in the pool
causing damage and a LOW pH

3. Add 1.0 litre HOTZONE (or similar) Algaecide per 45,000 liters. Repeat this dose mid-winter

In SPRING check the pool club page for the startup regime