Is it bad to leave pool dry?

[ChomDo]

So my sand filter is due for a change and I emptied my pool. I remember reading somewhere that it's not a good idea to leave a tiled pool dry for too long. Does this make sense or is it a false claim? I would expect that it has to be dry for some weeks at least or maybe longer. The sand filter is simply not doing it's job anymore so the water is impossible to keep clean – so was a must to empty it. 

[LarrySR]

If there is groundwater, it possibly could float the pool out of the ground like a boat, no?

[sometimewoodworker]

As mentioned, Yes it is bad to have a concrete boat as boats float even concrete ones.

[ChomDo]

Thanks for the replies but I'm really not getting the point. It's a 3x3m jacuzzi type of "pool" built in into the ground (concrete base and tiled) in my tiny back yard in BKK. I understood that the strong sun might crack the grout lines or something but not idea about this "concrete boat theory" you mentioned.

 

I would change the sand filter now if I could but the place where it's located is nearly impossible to access so I'll have to find some pool company to do it. I've noticed they are not easily willing to do small jobs like this. I also could't keep the water in there anymore since it was just getting totally rotten (green bubbly stuff) on the surface even with plenty of chlorine. 

[Saanim]

Cracks in an empty pool by pressure of ground water can occur at any pool, whether tiles or foiled. 

However, when no such ground water is present and in a dry season, there is no problem to leave the tiled pool empty.  Similarly as nothing happens  with tiled bathrooms and other large rooms, they are also not filled in with water. are they?

Besides, when such a tiled pool is constructed, it takes sometimes months until it is filled in with water, especially large pools. 

[Bagwain]

25 minutes ago, ChomDo said:

Thanks for the replies but I'm really not getting the point. It's a 3x3m jacuzzi type of "pool" built in into the ground (concrete base and tiled) in my tiny back yard in BKK. I understood that the strong sun might crack the grout lines or something but not idea about this "concrete boat theory" you mentioned.

 

I would change the sand filter now if I could but the place where it's located is nearly impossible to access so I'll have to find some pool company to do it. I've noticed they are not easily willing to do small jobs like this. I also could't keep the water in there anymore since it was just getting totally rotten (green bubbly stuff) on the surface even with plenty of chlorine. 

Ground water is nearly always an issue with BKK & surrounds. By all means empty it, however to be on the safe side I would quickly clean it and then refill asap! Changing a filter is not a large task. Fresh water will stay OK for a week at least with some chlorine added!

[ChomDo]

7 hours ago, Saanim said:

Cracks in an empty pool by pressure of ground water can occur at any pool, whether tiles or foiled. 

However, when no such ground water is present and in a dry season, there is no problem to leave the tiled pool empty.  Similarly as nothing happens  with tiled bathrooms and other large rooms, they are also not filled in with water. are they?

Besides, when such a tiled pool is constructed, it takes sometimes months until it is filled in with water, especially large pools. 

Thanks, this makes sense to me. I hope not to have it empty too long but it has been empty for some weeks before.

[ChomDo]

6 hours ago, Bagwain said:

Ground water is nearly always an issue with BKK & surrounds. By all means empty it, however to be on the safe side I would quickly clean it and then refill asap! Changing a filter is not a large task. Fresh water will stay OK for a week at least with some chlorine added!

Yea I emptied it and cleaned it yesterday. Hoping it can be done within a few weeks but I can't use the pump as it is now so feel like I shouldn't fill it up. Changing the filter is impossible for most people under the circumstances. Unfortunately only a very small person can get to this sand filter. It was built in a minimal space so some things had to be compromised making changing parts complicated.

[Saanim]

1 hour ago, ChomDo said:

Yea I emptied it and cleaned it yesterday. Hoping it can be done within a few weeks but I can't use the pump as it is now so feel like I shouldn't fill it up. Changing the filter is impossible for most people under the circumstances. Unfortunately only a very small person can get to this sand filter. It was built in a minimal space so some things had to be compromised making changing parts complicated.

Why cannot you fill up the pool? The filter connections IN/OUT are surely isolated by valves, so the pool can be full of water. If they are not, you have now a chance to install the valves. 

 

And what is the problem with the filter? If it is really not well accessible, you have got now a chance to change it. The filter should be easily accessible not only for the installation but for the regular maintenance, easy access to the 6-way valve when vacuum sucking, backwashing, draining.  

 

Also the pump should be easily accessible, after each vacuum sucking and backwashing the inlet basket should be cleaned up. And also the bottom under the basket is often full of a fine sand that is good to drain off by the bolt at the bottom of the pump (picture).

 

And you can buy a cheap filter at Global House fro 7,500 Baht. Such model (and the price) is however not salonfaehig for some who offer pools for 1 - 2 M,.  For me it works over 15 years OK.

 

 

[Saanim]

Just now, Saanim said:

And also the bottom under the basket is often full of a fine sand that is good to drain off by the bolt at the bottom of the pump (picture).

 

[SiSePuede419]

If the groundwater table is so high that it floats your pool, you got much bigger problems.

 

Probably should move your house up on stilts, because you in a FLOOD ZONE 

[LarrySR]

21 hours ago, ChomDo said:

Thanks for the replies but I'm really not getting the point. It's a 3x3m jacuzzi type of "pool" built in into the ground (concrete base and tiled) in my tiny back yard in BKK. I understood that the strong sun might crack the grout lines or something but not idea about this "concrete boat theory" you mentioned.

 

Not all boats are made of wood. 
 

[rwill]

If you are worried about sun damage why not cover the pool?

[bluejets]

22 hours ago, ChomDo said:

Thanks for the replies but I'm really not getting the point. It's a 3x3m jacuzzi type of "pool" built in into the ground (concrete base and tiled) in my tiny back yard in BKK. I understood that the strong sun might crack the grout lines or something but not idea about this "concrete boat theory" you mentioned.

 

I would change the sand filter now if I could but the place where it's located is nearly impossible to access so I'll have to find some pool company to do it. I've noticed they are not easily willing to do small jobs like this. I also could't keep the water in there anymore since it was just getting totally rotten (green bubbly stuff) on the surface even with plenty of chlorine. 

Basic physics really.........

https://mikethepoolman.com/why-you-dont-drain-your-pool/

[Bagwain]

16 hours ago, ChomDo said:

Yea I emptied it and cleaned it yesterday. Hoping it can be done within a few weeks but I can't use the pump as it is now so feel like I shouldn't fill it up. Changing the filter is impossible for most people under the circumstances. Unfortunately only a very small person can get to this sand filter. It was built in a minimal space so some things had to be compromised making changing parts complicated.

Maybe consider changing to a small cartridge filter!

[MrJ2U]

Ground water can actually push the pool up.

 

If you need to do it well into the dry season when groundwater levels are lower.

 

I've done it twice in the dry season for re-tiling and it's been fine.

 

They have valves to relieve water pressure.  While the pools empty install 1 or 2.

 

 

 

 

[ifmu]

On 12/9/2021 at 9:48 AM, ChomDo said:

Thanks for the replies but I'm really not getting the point. It's a 3x3m jacuzzi type of "pool" built in into the ground (concrete base and tiled) in my tiny back yard in BKK. I understood that the strong sun might crack the grout lines or something but not idea about this "concrete boat theory" you mentioned.

 

I would change the sand filter now if I could but the place where it's located is nearly impossible to access so I'll have to find some pool company to do it. I've noticed they are not easily willing to do small jobs like this. I also could't keep the water in there anymore since it was just getting totally rotten (green bubbly stuff) on the surface even with plenty of chlorine. 

yes its also my understanding that if the ground water is high then the pool will dislodge and  float up 

[MadMuhammad]

Just make sure you cover it if it looks like rain, don’t want it getting wet 

[sometimewoodworker]

On 12/9/2021 at 9:48 AM, ChomDo said:

I understood that the strong sun might crack the grout lines or something but not idea about this "concrete boat theory" you mentioned.

It is no theory. It is fact.

a boat is a watertight hollow structure and for it to float the weight is less than the volume of liquid or semiliquid it displaces.

When full of water your pool is equal or a bit greater in mass than the hole it is in so it stays in place, take the water out and you have a boat, with the correct conditions (bad for you) the lift available is  a lot greater than the mass of the concrete, QED you have a concrete boat, for the theory Archimedes principle applies 

 

 

 

You do not have to have a high water table, heavy rain can be enough. All you need for your pool to rise is semiliquid soil.

 

can you be absolutely sure that your soil will allow water to drain away fast enough that this is not going to happen to you?

as to current in use concrete boats 

and decommissioned barges

 

 

[RJRS1301]

On 12/8/2021 at 10:42 PM, sometimewoodworker said:

As mentioned, Yes it is bad to have a concrete boat as boats float even concrete ones.

Post surpurfluous to need, deleted

 

[ChomDo]

On 12/9/2021 at 7:21 PM, Saanim said:

Why cannot you fill up the pool? The filter connections IN/OUT are surely isolated by valves, so the pool can be full of water. If they are not, you have now a chance to install the valves. 

 

And what is the problem with the filter? If it is really not well accessible, you have got now a chance to change it. The filter should be easily accessible not only for the installation but for the regular maintenance, easy access to the 6-way valve when vacuum sucking, backwashing, draining.  

 

Also the pump should be easily accessible, after each vacuum sucking and backwashing the inlet basket should be cleaned up. And also the bottom under the basket is often full of a fine sand that is good to drain off by the bolt at the bottom of the pump (picture).

 

And you can buy a cheap filter at Global House fro 7,500 Baht. Such model (and the price) is however not salonfaehig for some who offer pools for 1 - 2 M,.  For me it works over 15 years OK.

 

 

Thanks for all the replies. I'll just reply to this one first.

 

Of course I can fill up the pool. Mine takes only 6 cubic meters of water so no issue, but it won't take long for the water to get all toxic again since the pump would just push out a dark cloud of dirt – so obviously I can't have the pumps running. Just seems like a waste of water and time at this point, but if this floating theory makes sense at my house, then it's worth it yes.

 

And all the normal maintenance stuff you mentioned there I do regularly of course. I'm only talking about the difficulty of getting the sand changed. You need a lot of space to do that work.

 

Believe me it's impossible for a normal sized person to get into the box there the pump is. I can do all the general maintenance myself of course but to change the whole sand filter, someone needs to actually go in there fully and have space to work. Also pool companies are not fond of doing small and "tricky" jobs like this. If someone has a person/company to suggest in BKK that would be great. 

 

Might have to take down the structure around the pool system and pipework. I'll just add a few pictures here so you get it what I'm talking about. 

[Saanim]

2 hours ago, ChomDo said:

Believe me it's impossible for a normal sized person to get into the box there the pump is.

Perhaps you could dismantle the wooden box, at least partly, to remove the front side. Afterwards, thinking when put it back how to fix it for any future similar job to have it Knock Down - something like K/D furniture.

     

[Saanim]

^ Seeing your piping, my idea: cut off the pipes to the filter to be able to lift up the filter.  Then, when putting it back, use a removable Union connection for the re-connecting.     

[Bagwain]

1 hour ago, Saanim said:

^ Seeing your piping, my idea: cut off the pipes to the filter to be able to lift up the filter.  Then, when putting it back, use a removable Union connection for the re-connecting.     

Waste of money considering the filter already has these! Again you are wasting your breath with your massive 1 backyard pool experience! Plus adding these only offers more places to fail & leak!

 

A Thai person would easily get in and remove the connections. However not needed.

Best just to change media! We have done it many times!

It would be best to use a "wet vac" to suck out the old media and recharge with new!!

i recomend "Eco Clear" Recycled plate glass as apposed to sand. Eco last up to 15 yrs.

No sense in knocking anything down! 

 

 

 

 

Eco Clear.pdf

[BostonRob2]

Yes, I always have a beverage handy when playing pool. 

[ThailandRyan]

Just fill it in and make a yard

[Saanim]

22 hours ago, Bagwain said:

i recomend "Eco Clear" Recycled plate glass as apposed to sand. Eco last up to 15 yrs.

No sense in knocking anything down! 

With my backyard pool experience (sorry to correct it, there have been 2) I would not recommend any fancy glass filling. A quartz sand that is in the river for millions years is the best cleaning medium, just to backwash it, can serve for zig years without any change.. 

 

The only disadvantage: is so cheap, even can get it free...

     

[Bagwain]

20 minutes ago, Saanim said:

With my backyard pool experience (sorry to correct it, there have been 2) I would not recommend any fancy glass filling. A quartz sand that is in the river for millions years is the best cleaning medium, just to backwash it, can serve for zig years without any change.. 

 

The only disadvantage: is so cheap, even can get it free...

     

Ridiculous. Maybe you are trying but still ridiculous!! You have absolutly NO idea what you are talking about! 

The scary thing is, someone may take your advice & end up costing them a lot of money!

No point in giving you details about silicate, river sand or other media for filters as you are the expert from another planet!???????? 

 

[Saanim]

1 hour ago, Bagwain said:

The scary thing is, someone may take your advice & end up costing them a lot of money!

Should  I offer to make for them a pool for 1.4 - 2 M?

[James William]

External damage can be caused by sustained pressure on an in-ground pool without water, which is why it is not advisable to leave a pool empty for extended periods. A drained above-ground pool can cause structural damage from the elements.