Removing excess water from salt water pool

[PeteC]

I made a discovery that may be useful to some. Where I am we've had torrential rains over the past two weeks and normally this would mean I had to pump excess water out of our salt water pool. I didn't do it and at least 6" of water overflowed. When checking the degree of salt in the pool I found it was no different after the rains than it was before the rains. Salt water is heavier than fresh water so the rain water simply sat on top during the storms, and subsequently went onto the lawn and garden. No harm done, nothing has died and in fact looks great.

So, why pump out your salt water and money from the bottom drains which would indeed deplete your salt content given salt water is heavier and is down where the drains are. Just let the newly introduced fresh rain water overflow.

I'm going to stick with this theory/practice until I see something wrong with the logic and results. Pete

[SunandFun]

The only reason I can think of is that the salt water pool you have, does not use overflow filtering but uses a skimmer filter. If you have an "infinite pool" then it is the overflow type. With this I would assume that you can just let the water flow over. But with a "skimmer system" the water level is normally below the top line of the pool and is about half way up the skimmer opening hole. There is a basket inside the hole. If the water level goes to the top of the pool, I find the water does not move and the filtration becomes defeated.

[Dannie Boy]

I would also have thought that if you have the pump on circulation for about 6 hours a day, the rain water is going to get fairly mixed up with the salt water?

[Nereus]

I think that both posters need to read that which Pete has posted. He is simoly saying that there is a good reason to allow a pool to overflow when rain fills it over full. It is immaterial what type of pool it is, the point being that it is fresh water flowing into the garden, not treated water, regardless of it being a "salt" pool or any other form of sanitation,"infinite pool" or "skimmer system".

[PeteC]

I only run filters from 0600-0900 and 1500-1800 which has proven enough. Great majority of rain has been coming outside of those hours. It's an overflow pool. Pete

[SunandFun]

I only run filters from 0600-0900 and 1500-1800 which has proven enough. Great majority of rain has been coming outside of those hours. It's an overflow pool. Pete

Thanks Pete. That is what I thought. With overflow the filtration continues. With a fixed level pool where you have 6-10 inches below the top edge of the pool for the water level, it does not work, therefore you have to pump it out to allow it to filter properly. But I think the excess water that you pump out comes from the skimmer which is located at the top of the water line. So as you said, you would be removing the lighter, unsalted water from the pool. Thanks for clarifying.

[PeteC]

^ I need to clarify some things. There is no skimmer on an overflow pool. There is a trench around the pool which I have 1/2 filled with river stones sitting on top of a plastic grating. The 1/2 beneath that is open water flowing space. So, you could say the water is filtered by going through the stones, but not really, but it does catch leaves and other surface debris like a skimmer basket does.

The water then goes into a 6,000 gallon below ground holding tank at the far end of the pool, and that's where it sits until you turn the filter on. If the rain is such that the holding tank fills up as well as the pool, the tank overflows up through the vent hole in the cover covering the access hole (about 1/2 x 1/2 meter square)...large enough for a man to get down into the tank. Nothing moves or is filtered from the pool or the tank if the filter is off.

My system has two locations from which water is drawn into the filter. 1) The holding tank 2) The two floor drains. I can pick, choose and mix as I need to.

To finish the picture, the water is returned to the pool through five floor locations, again you can choose which and how many you open. Given there is no skimmer, vacuum intake ports are 6" below the surface directly in the wall on either side of the pool. Pete

[Nereus]

Thank you Pete, you just saved me a frustrating time trying to explain what you have just posted! It must be a big pool to have such a large buffer tank. Some people seem to think that because it is an infinity pool that the filtration system is different from a skimmer type.

[PeteC]

Not super big. One half 10 x 7 meter and the other half 10 x 9 meter. Kind of like a backwards "P" shape, the top of the "P" being either a kids pool or a water jet pool for aching old bones! This section flows over a ledge into the main pool. No heater needed as in the sun and only 1/3 of a meter deep. Deep end 1.8 I think...never measured it. Again, I was told by the company about the capacity of the tank. It's 7 meters wide x about 1 1/2 meter and 1.8 deep as I've been down in the bloody thing. It's like being in the cold pit of doom.....watch out for sea creatures! The suck pipe into the filter has a guard on it to stop any debris and from time to time I need to clean out the grooves, dead chingchokes, damn pigeon feathers and the occasional floating mouse! Pete

[Nereus]

Ok, thanks. The rule of thumb for buffer tanks is around 10% of the pool capacity. Some of them are fitted with either a float switch for a pump, or a float valve if a good water supply, to ensure that the filter pump does not run out of water.

I believe it is good practice to have the main drain valve "cracked open" just a bit to also ensure no water starvation. I used to run mine like that until some "know it better" Thai changed the piping in my absence, so now it is not possible to pump any water out of the main drain even if I needed too.

[PeteC]

Indeed on the main drain. I have one closed and the other 1/2 open. Good enough if any emergency with the tank flow into the filter.

EDIT: How are your going to completely drain the pool when time comes to re-grout or other? I guess you'll have to use an electric or motorized pump.

[Nereus]

Yes, I guess a portable pump. I tried to get another contractor to put it back how it should be. He gave me a price and then when he went to do it came up with all sorts of reasons why it did not need doing!
The main problem is that the idiot that changed it cut the standpipe to the manifold that close that it is now impossible to reconnect a pipe too it. It would need to half rebuild the manifold to be able to re-connect it how it should be.

The house is now let out on a long term rental, so I have not bothered doing any more about it.

[Bluesky]

If you need to remove water from the pool normally you can achieve this by closing off the skimmer box draw pipe so that water is drawn from the hydrostatic valve/waste drain located in the bottom of the pool. set the Spyder valve to 'Waste' and switch on the pump. water should then flow through the waste pipe and reduce the level of water in the pool. If this is not available there are available in thailand electrically powered submersible pumps at a reasonable price. They generally come in a two pin configuration with an earth clip.(strongly suggest using the earth clip at all times by connecting it to an earth stake) they are available in a number of head pressures and flow rates ( depending on how fast you want drain the pool) the only addition would be a suitable length of layflat hose attached to the outlet with a jubilee clip that ran reach the area where you wish to dispose of the salt water. (Don't run the pump dry or it will damage the seal) Suggestion: If the salt levels are too high it will damage fittings, chlorinator and the finish on the pool surface. The manufacturer of your salt cell will have have the specification for this. If you need further info let me know. ( Please note knowledge is based on pool construction and maintenance in Aust)

[Bluesky]

apologies! missed the earlier posts on this as I could only view the last two items posted!

[williamcooper]

Thank you for sharing the information.