Swimming Pool Water - Pump Or Purchase?

[up2you2]

Is there a formula for calculating how much it would cost to pump up a cubic meter of water, from a well to supply a swimming pool?

Various factors I can think of, the height of the well, the distance to supply the pool, and the minimum wattage of the pump required to fulfil these requirements.

The cost of maintaining and servicing the pump would also be a factor.

I have just paid 500 Baht for 5,000 cubic litres of water.

[monty]

Very difficult to say, as the submersible pumps are made in many different models to suit the well you use them in.

The absolute minimum you'll get will be around 5 GPM, but likely if the proper pump is chosen it'll be more like between 8 and 10 GPM.

This is using 1/2 - 1 1/2 HP pumps.

Examples of flows/depths/pressures for Franklin pumps (widely used/sold in Thailands) are here:

http://www.franklin-electric.com/media/documents/995189.pdf

So your average 3/4 HP uses around 1 KWh of electricity every 1.5 hours. It'll pump on average 7 GPM or very roughly 1500 liters/hour.

Works out to under 2 Baht/1000 liters in actual electricity costs.

So filling a 30,000 liter pool would cost you 60 Baht in electricity (and a fair few hours of patience!).

These pumps can pump a massive amount of water before maintenance is needed...Filling up a pool will not make much of a dent in their lifespan...

As a comparison, 1000 liters of city water will cost you around 15 Baht.

BTW, I'm not sure what 5000 cubic liter of water is

[SantiSuk]

I was amused by the prospect of there being square litres, too

City water is pretty expensive then. I replaced 10% of my pool water yesterday with Isaan village water (treated, but I wouldn't want to drink it). Approx 8,000 litres and 8 units on my meter = 32baht = 4 baht for 1,000 litres. I tested it and its even pool friendly - TA at 100, a trace of cyanauric and chlorine and a nice low pH of 6.8 to compenaste for my usually alkaline-tendency pool.

Normally the pool auto tops-up from our well and its nice to know that this is not a higher cost option, so thanks for the info, Monty: I was musing about it myself over yesterday. Our village water man doesn't like having his domestic supplies being used regularly for 'non-domestic' uses I'm told but of course every man and his dog makes some semi-agricultural use of it.

[AllanB]

First of all forget about the costs of servicing a pump to fill your pool, there are none. Next forget about the cost of electricity associated with this, unless your well is very, very deep, in which case your major cost will be buying the very expensive pump.

You need to select a suitable self-priming pump that will handle the head of water (depth of well) and then look at the graph of the pump to see the flow-rate, if you are interested, but if it can't lift the water it won't work at all and remember to add a % if you have a long horizontal run.

Next is the quality of the water, if there are any issues there, it is best to filter the water as it enters the pool, rather than when it is in. When you are looking at filtration, make sure the filter can handle the flow-rate of the pump, so that the time between cleaning isn't too short.

We use a large 1 micron bag filter, which takes out most contaminates, algae, bacteria and even parasites, but needs cleaning regularly, so would select a lower flow pump. We have a 40 m3 pool, a not too clean supply and empty the filter about 20 times, but end up with crystal clear water, they are not expensive so have two, one in use and one in the wash.

[Chaichara]

The max and minumum pH for pool water is 7.2 - 7.6. For chlorination to function correctly, these parameters should be strictly maintained. Use hydrochloric (muriatic) acid, or proprietary 'pH Minus' (dry acid) to lower the ph, and 'pH Plus' (soda ash) to raise it.