Wall height difference...

[CliffTex]

We just got through filling up our 16x26x52 pool and was concerned about the depth differences against the walls. During the filling process we were monitoring the water level and found one side seemed to either be dropping or the other side raising. After the pool was full, there was about a 2 inch difference in depth on one straight wall vs the other. There are no buckles in the wall nor bulges in the sides. During the ground preparation our difference was only about 1/2"-3/4" at worst. Our pool has the external buttresses and again it looks very stable but it is just high on one side. Our base material was decomposed granite on a mostly rocky terrain. We only have about 2" of topsoil which was removed and replaced with the granite.

Should we be worried?

[hrsdennis]

Hi, I would say not to worry. If it stays the way it is, and it should, you should be fine. Just watch it, if it is settling, it could continue to do so. 2" is not that bad.

Best of luck, Dennis

[matt4x4]

Ok, I have to question something here.
About 1.5 to 2 years ago - (pre Dennis), it seemed to be standard practice on this forum that a 1" height difference on a 24 foot round or larger AG pool is acceptable, and that seemed relatively sensible to me. We had many members who were very knowledgeable when it came to building an above ground pool, that number seems to have dropped off a bit, but we have also gained a few very knowlegeable people such as Dennis.
A year later, this number seems to have risen by 100% (over way less of a distance - 16 feet), which works out to 2.66" over 24 feet, and 4" over 32 feet - now this number is HUGE, now I'm not here to argue this number, I'm only questioning it. I'd like to see some continuity here, and sure hope that the acceptable difference does not jump to 6 or 8 inches in a few more years, before we know it people are just going to throw an AG pool up on a hillside :) , I know Dennis builds a LOT of AG pools and likely knows what is and isn't acceptable/safe, however, if a professional built my pool with that much difference, I'd have to really question it and likely make them fix it.
When I started asking these questions before building my pool, I was told to try and keep it within 1/2" (over 30 feet), now that's relatively hard to achieve on clay soil, however, I used screenings (crusher run) as my wall base and when it was all said and done, 1/2" was all that my pool was out. First winter's frost however, changed that number to about 1", where it seems to have held steady for the past 2.5 years. I sure would not want ot see my pool on a 4" slope over 30 feet - the darn thing would look like the Titanic moments before the big whoosh!

[hrsdennis]

I guess I need to explain a little more on my theory of the correct level tolerance for an above ground pool.

Most instruction manuals allow a 1” tolerance for warranty purposes. This is a good rule of thumb for anyone. Pools just look a lot better when they are level.

It was over twenty years ago the last time I had a customer question the level of a pool I had built. When I went to look at the pool one side had settled a little and the overall difference was 1 ¼”. I ask that we drain the pool so I could make it perfect. If a pro can’t build a pool at least within a ½” every time they should find a new occupation.

I change liners in and service a lot of homeowner installed pools. Those are the ones I am talking about. When someone puts hours and hours of hard work into building a pool it’s tough for me to say that the pool is over an inch out of level and is therefore not safe.

There are so many factors involved there is no right number for every case. In the above example I based my opinion on several factors. This pool was installed on a solid granite foundation. This pool also has an external buttress system. I also know this pool has a foam base with a preformed pool cove. All of these things point to a good solid construction that will accept a little more variance level wise. If this pool were a buttress free design, on a sand base, with a sand cove I would want more info before I would suggest they might be ok 2” out of level.

A big factor with regards to safety is what’s going on around the pool. A pool 2’ in the ground can be 6” out of level and be perfectly safe. They don’t look so pretty but they are safe. A pool set in the ground a little or one with a good birm built around it tends to be little more tolerant level wise.

I use a laser level and set all of my pools as close to perfect as possible. I recommend for everyone to do it that way. I also recommend patio blocks, mostly because they are such a good leveling aid. If you have twenty or more patio block all set at exactly the same number it is hard to build an out of level pool.

Sometimes a lot of hard work goes into something that is just not perfect. Those are the ones that have to be looked at case by case, pool by pool.

Matt brought up some good points and I hope I have convinced everyone I am not a fan of out of level pools. To dump all of that water, run the risk of the liner shrinking, and putting many more hours of labor and money into the pools is something that does need some thought. And as for 2" in 16' = 4" in 32'. I see it just the opposite. The larger the pool the more level it should be. The smaller the pool the more tolerant. Oval buttress pools even more so, they are so well supported on the sides.

Later, Dennis

[CliffTex]

Thanks again for all the input Dennis and Matt. I will continue to monitor the pools level and keep you guys updated if anything else changes. We have just gotten a ton of rain and I am hoping the high side will fall and the low side will not. All in all, I keep reminding myself of the money I saved in this whole project after buying a used pool and installing it myself with a new liner including a small deck for $1600. Heck, the kids don't care if its level and they are what its all about...:)

[matt4x4]

Thanks for getting back on this Dennis, I see your point about the solid base, as Cliftex said - if the kids don't care.....
I just wanted to be sure, the numbers just didn't jiive with what i was told by all 3 years ago.
I'd have to shoot myself if my pool was 4" out, only because i really wouldn't want to do THAT again and shooting myself would get me off the hook!

[hrsdennis]

You are very welcome CliffTex, hope those kids enjoy the pool. I know mine always have.

We really are on the same page Matt. We both agree the ground prep is the most important part of the job. Build the pool on firm solid ground and whatever method of leveling you choose, do it good. The rest will go fairly easy.

As for the one inch rule. When building your pool forget it. Set everything perfect. Take the time to make it perfect by whatever means you have available. The one inch rule applies after the pool is full.

It is not uncommon for the ground to settle due to many factors. When you measure from the top rail to the water level all the way around the pool it should be within an inch.

If it is not, that's when the questions arise. Is it safe? Should I drain it ASAP and redo? That's when I say let's take a look at your particular situation and see what would be best. No hard fast rules here, just some good pool sense.

Have a good one, Dennis

[NWMNMom]

Ours was so perfectly level (I made my DH crazy with the transit several times a day during install) when we prepped and installed in our usually wet yard and then we had the "big drought" this summer (biggest in the northern plains since 89) and even a lot of the normal subsoil moisture dried up. So, long story short, our "plump" ground shrunk and shifted slightly back there and I do notice a slight difference of maybe 1-1.5" or so - not side to side but from one end to the other. I'm hoping that we do not have an unusually wet fall or spring.....