Environmentally Friendly Swimming Pool

Let me get one thing clear up front.  A normal backyard swimming pool is not very environmentally friendly.  Full stop.

Ah, now I have that off my chest, the rest of this post is about how we try and minimise our environmental impact when maintaining our pool.  Our pool contains about 60,000 litres of water.  That is a lot of H2O.  As any body of water is subject to evaporation, how do we either prevent this from happening or when required, top it up?

To prevent evaporation, we have a pool blanket, which is made from a thick plastic material that has little bubbles all throughout it so that it floats.  Think of it as very thick bubble wrap.

We roll this out as the weather warms up and it serves two purposes.  Firstly, evaporation loss as mentioned, and secondly, it helps heat up the pool quicker as it acts like a greenhouse and insulation.  When we use the blanket the first 50cm to a metre is about 38C (100F), and the water below is still about 17C (60F).  So we jump right in and stir it all up bringing the temperature down to about 21-25C.

As we do still get a little evaporation loss, this is what I use to top it up.

Our main rainwater tank gets dumped into the pool when we know there is a storm coming and that it will be filled back up again.  Also, if the tank does get full over a period of days, I connect the garden hose to the first flush diverter (the pipe to the right of the tank with the black hose on the end) and run it into the pool.  These two methods keep it topped up over the summer.  I have bought a second tank that will be installed when my Dad comes to visit in November, so I will have more water do divert into the pool, and to keep my veggie patch alive during those very hot days (45C) we get here sometimes.

Pools are notorious energy guzzlers, and when I bought the house in the year 2000, mine was no exception.  It had a thumping big 3kW pump motor, which fortunately died after about 2 years, and I replaced it with a more efficient 1.1kW pump.  This pump is still not as efficient as I would like, so when this one pops its clogs, I will be looking for an alternative.  Either a DC brush-less pump powered by solar panel, or a more energy efficient AC pump motor.  It shouldn’t be too long as I can hear the bearings going in this pump already.

When the pump is running, the device called a “Creepy Crawly” makes its way around the pool and cleans/sucks all of the silt off of the bottom.  This water then gets filtered by a media filter then returned back into the pool all nice and clean.  However, we had another device in the middle of all this.  We have a salt water chlorinator that has a cell that splits the two molecules within the salt (Sodium & Choride).  The sodium sticks to the cell plates, and the chloride, now chlorine is returned to the pool to keep the bacteria levels down, without the addition of copious amounts of dry or liquid chlorine.   This is a great environmental feature, as all we have to add to the pool is salt in big 20kg bags each year.

So we have covered water and chemicals.  What about the media filter?  Well the sand filter we had up until about a month ago needed to be backwashed, (which is just a fancy term for cleaning and dumping about a thousand litres of water in 5 minutes down the drain) about twice a week.  This used to piss me off to no end at the thought of having to dump that water down the drain just to clean the silt out of the filter.

Like I mentioned before, we replaced the old sand filter with a much more efficient device.  Enter the new media filter the EcoPure F25.  I am not sure which part of it is ‘eco’ but I do know that it does not need hardly any backwashing every month.

It does not contain sand, but is filled with a medium called Zelbrite, which is basically crushed zeolitic volcanic rock in a granular form.  It collects more silt because is attracted to the Zelbrite and therefore requires less backwashes and less water wastage.  In the one and a half months I have had this new filter, I have backwashed it once, and it took 30 seconds to clear instead of the normal weekly clean and 5 minute flush!  I am so pleased, and it all cost only $100 more than a normal filter and filter medium.

As for running the system, one pool guy told me that I needed to run it for at least 8 hours in summer and 4 hours in winter to make the chlorine and filter the water.  If I took his advice then I would use at least 9 kWh of electricity in the summer just on the pool.  Well, not one to follow the pack, we filter for 2 hours a day in summer, and I clean the pool manually on a Saturday morning during warm weather which only takes another hour.  So from a recommended 63 kWh a week to just 15 kWh using my method.  The chlorinator makes less chlorine due to less pumping time, so I combated this by using a simple floating chlorinator that I put a few large chlorine tablets in once a week, to keep the levels up in summer.  In winter, I don’t add it all.

All in all, I believe that the methods that I use save water, electricity and chemical additives, which can only be a good thing for the planet, and all those who swim in the cement pond!


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