Posts Tagged ‘zero edge swimming pool’

Building a Zero Edge swimming Pool – Vanishing Edge Pool Infinity Edge Pool? Beware!!

Thursday, March 24th, 2011

Building a Zero Edge swimming Pool – Vanishing Edge Pool Infinity Edge Pool? Beware!!

The other day, I visited a woman who was interested in an outdoor kitchen. We looked at the space, and I shared some ideas with her. On the way back to the house, she asked, “You build swimming pools, right?” I said, “Of course.” She then told me she was having someone repair the tile on her zero edge pool, AKA  infinity edge pool or vanishing edge pool and asked if I would take a look at it. “Sure,” I replied, but in a few minutes, I was also sure she wished she never asked the question.

The tile was falling off, and the plaster was cracked throughout the collection pool at the bottom of the infinity edge wall. Noticing that there was probably a more serious issue with the pool, I asked her if I might come back the next day to remove the cover and see what was causing the problem.

The next day, we removed the cover and saw that the vanishing edge inground pool design was in need of much more than a simple tile repair. After four years, this $150,000 infinity pool was in horrible condition. Here’s what we found:

NJ vanishing edge swimming pool Zero edge pool infinity edge pool

NJ vanishing edge swimming pool Zero edge pool infinity edge pool

Gunite Rebound

The weir wall (i.e. the wall of the pool that showcases the infinity edge) was cracked in several places. Initial core samples show signs of “rebound” encapsulated in the wall. When the gunite is sprayed and applied to the pool, a certain amount bounces back. This “rebound” should be discarded before the gunite is shot over it once again. If not, useless gunite is trapped beneath the surface, creating pockets of nonstructural masses in the walls, in this case the weir wall. This threatens the structural integrity of the wall that withstands tremendous pressure from the pool water all on its own (i.e. without the support of surrounding soil). This can be dangerous when the rebound forms weak deposits of unusable gunite scattered within the wall.

Calcium Deposits

What was left of the tile on the weir wall had severe calcium deposits all across the surface, producing a white stain on all of the tiles due to a process called efflorescence. During this process, water enters the pores of the weir wall and slowly travels through to the other side, picking up salt and minerals from the concrete along the way. When it reaches the other side, which in this case, is covered in tile, the water evaporates and leaves the salt and minerals behind. The salt and minerals form calcium deposits on the tile and may lead to cracking. They appear in the form of white stains.

Plaster Cracking

Due to the structural failure of the weir wall, the Pebble-Tec pool plaster, a 20-year rated finish which probably cost the homeowner about $35,000, was cracked throughout the lower weir wall and needs to be replaced after just four years.

Poor Construction

To wrap things up, we checked the level of the weir wall, and it was 3/8 of an inch out of level, which is significant when you’re dealing with an infinity edge pool.  If the pool were 1/16 of an inch out of level, the infinity edge could run on a 1 hp pump to move the necessary 25 gallons per minute over the edge of the weir wall. The pool builder on this project used a 4 hp pump, which can move 400 gallons per minute over the infinity wall, to compensate for the lack of precision, taking “playing it safe” to a whole new level. Also, a 1 hp pump runs on 3.5 amps as opposed to the 20 amps of a 4 hp pump. In other words, by having a level infinity edge and using the appropriate pump, the homeowner could have cut energy usage for the water feature by 80%.


If a pool company is going to advertise a vanishing edge swimming pool on the internet or in a print ad and it interests you, make sure you ask to see that very pool as it stands today; furthermore, look at all the pools they are promoting that might interest you and try to see several examples of the pools they are advertising! When you go see the pool, be sure to get a perfectly good look at the infinity wall itself, not just the view it overlooks. If done right, infinity edge pools showcase every essential skill of a quality pool builder. If done wrong, these pools won’t be able to hide it. Here are a few things to look for when visiting that vanishing edge swimming pool:

1. The flow shows best. Take a look at the working infinity edge and make sure the water flows all the way across the vanishing edge. An even flow over the edge will show you that the swimming pool is level and did not settle in the ground due to poor soil conditions and bad engineering. Then, check the pump size and make sure the pump is not oversized to compensate for imprecision.

2. Have the contractor turn the water off and look at the top of the weir wall. Make sure there is no discoloration or cracks in the tile at the top of the weir wall. With the water off, you will be able to really focus and see any possible imperfections.

3. Check where the pool meets the patio on every side. There should be a consistent joint where the pool meets the patio. Be sure that there is no separation. If there is, the pool could be settling or rolling as a result of problems with soil, drainage, or slope.

3. Examine the backside of the weir wall. Are all the tiles intact? Are there tiles popping off? See that there are no cracks in the joints of the tiles as well. These problems could mean that the weir wall was poorly constructed or improperly sealed.

4. Do you see any discoloration in the tile on the weir wall? Calcium deposits will lead to big white spots on the tile. While this may occur in slight moderation, you certainly don’t want to see it throughout the weir wall. If you do, it is a good sign that there are voids or “shadowing” (i.e. empty spaces behind the rebar) in the gunite. Either way, water is travelling through the wall and leaving salt and minerals behind when it evaporates, which is not good.

5. In the trough or collection pond, closely examine the plaster. Make sure there are no cracks, spider cracks, or deformities. If the finish is cracked or deformed within its lifespan, it could be because there is water traveling through the weir wall and damaging the outer surface material. The collection pool should have just as smooth a finish as the inside of the pool.

Bonus: Visually take note of the length of the weir wall. If the wall is within 1/16 in. from level, the infinity edge will need 1 gallon per minute for every linear foot. Ask the pool builder what size pump he uses to run the infinity edge. Any weir wall 25 feet in length or less should be running on a 1 hp pump. If the pump is too big for the wall, the swimming pool contractor could be making up for imperfections and costing the homeowner unnecessary money on operating costs.

Remember, “you don’t know what you don’t know,” and that’s dangerous in the pool business! The swimming pool contractor who built this pool has been in business for over three decades and just followed standard pool building practices, which in this case contributed to the pool vessel failure. Do your due diligence! If you see a swimming pool contractor advertising pools that you like, demand to see them!

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