“I'd rather regret the things that I have done than the things that I have not.”
― Lucille Ball

Monday, March 26, 2012

Swimming Pool - Water Treatment

Right is our swimming pool as it was before and left after the water treatment system was installed and configured.

In a previous post I described and showed you the construction of our swimming pool. In this post I will focus on water treatment.

The chemical balance is now as it should be. The water is crystal clear. after many weeks of installing new water treatment equipment, learning how to operate it, trying chemicals, removing algae, testing the chemical and physical balance of the water and deciding what to do after each step.

The main problem with swimming pools is, especially in the tropics, that algae (microscopic plants) easily come into the pool (wind, birds, etc.) and start to multiply into millions coloring your pool green or yellow or black. Because of the high temperature (usually 30+ degrees Celsius), the algae really explode. Today the pool may be cristal clear, the next day its greenish and one day later you can't see the bottom anymore.

So you really need to treat the water. There are many solutions to it, usually with chemicals like chloride, algaecide to remove the algae, acids, carbonate, salt, metals. I am going to describe the solution I selected and why, the way I did it, the problems I had and the final results, together with some measurements in graphical form.

Another annoying problem is aquatic insects, swimming in your pool. In my case it is probably the "back swimmer" as it swims upside down. If you don't do anything they reproduce explosively like the algae do. I do not have this fully under control yet. Every day I remove them with a net, next day they are there again, probably from the eggs of their parents. I expect that when all residual dead algae on the bottom has gone (vacuum, filtering) the insects will disappear as that might be the food for the insects.

If you want to see the details of how and what I did to install the water treatment system, please see my Picasa web album. Click on the button Slideshow top left and change in the viewer the display time from 3 to 6 seconds, so you can read the comments.

Next part of this post is a more detailed and a bit technical description, for interested readers.

First of all I made a Pool Maintenance Log or PML. I will share this PML, so click on it and you can have a look at it. There are a couple of tabs like Profile (definitions), Actions, Maintenance and three tabs for different graphs, based on the records in the Maintenance tab.

Sanitizing is needed to eliminate or reduce things like urine, viruses and bacteria. Usually this is done by adding chlorine to the water or by adding salt and splitting the molecule in Natrium and Chloride by an electric current.

Of course you can treat the water manually measuring the chemical water balance and adding the right volume of chemicals to the pool on a daily or weekly basis. However I wanted a (semi) automatic system, that can easily be operated by a Filipino after some training in case I can't do it anymore.

By doing some research on the Internet, I found the system I believe is best for our pool. The system is based on technology and research from NASA as used in the Apollo space station, the ones that flew to the moon last century. The basic principle is adding copper ions to the water, this will protect the water against algae and kill bacteria.

The system is developed, manufactured and marketed by EcoSmarte. There are basically two systems. The Standard Turbo system works with one chamber and two sets of plates and a simple control box. A set of copper plates, when an electric field is applied, generates copper ions in the water, killing algae and bacteria. The other set are titanium plates, when an electric field is applied they oxidize the water and as a result all kinds of residual materials e.g. urine will be removed.

The Fully Automated system comes with a programmable control unit and has an additional CO2 (Carbon Dioxide) chamber, where CO2 gas is injected in the water, similar as in a beer pump. CO2 is an acid, so it is used to reduce the pH of the water if it has the tendency to go up by itself. By trial and error I have to find out how many minutes per day the system should inject CO2 and fine tune it.

After dealing with the company EcoSmarte I got a good price for the Fully Automated system and ordered it from the USA, as they don't have a dealer here in the Philippines. It took only one week by UPS, but customs in the Philippines delayed the transport with more than a week and I had to pay quite a lot of import tax. 

When the whole set - including a water management test kit - was received I started to change my pool plumbing, moved the filter to the right of the pump to create a place for the CO2 cylinder and inserted a long 2 inch pipe as to be able to integrate the two chambers in the piping. For more details have a look at the pictures in my Picasa web album

Just a funny intermezzo.
One of the Integrated Circuit (IC) chips in the controller is made by Philips semiconductors, which was sold out in 2006 and since then is called NXP. I used to work for Philips long time ago and NXP until recently. As the brand name Philips is on the IC (P89C54UBAA), it must be as old as 6 years or more. Actually it is an 8 bit microcomputer and on board flash EEPROM, so the heart of the system.

I also changed the way to fill the pool. Previously I did it with a flexible 3/4" hose, but the hose has a lot of algae developed inside from the sun. So I connected the deep well pump directly to the PVC return pipe coming from the filter, with some ball and check valves and unions. 

The system and pump were operated for 7/24 hours the first week, as instructed in the manual, ionizing copper and filtering the water continuously. And frequent water samples were taken, see my PML.

Algae plants need alkaline water, that means water with a pH greater than 7.0, which is the figure indicating that the water is balanced, not acid and not alkaline. If lower than 7.0 it is acid. The pH scale is logarithmic and goes from 0 to 14. So it is important that the pH value is close to 7.0.

Our well water, which I used for filling the pool, has a very high alkalinity level, I guess it is 8 or 9+, but it might also be that this high figure became even much higher as a result of alkaline components from the cement, sahara or grout used to build the pool, is dissolved in the water. Sahara is a powder that, when mixed with the cement, makes the concrete water resistant. By the way here is the pool filling graph (scatter diagram) I made, based on the maintenance records in the PML.

So initially I had to add a lot of acid to get the pH down. Finally I added more then 10 gallons of Muriatic acid (26%) in a pool of 93 cubic meters.Because I had to add so much acid, I really was doubting whether I did it right or missed something. The following diagram shows the acid addition over time.

Muriatic Acid adding over time in gallons

Apart from acid I also added chlorine (Trichloroisocyanuric Acid) which has a very low pH of 3, so very acid as well. EcoSmarte advised me to add chlorine, as the chlorine level should not be zero when you start the operation of the water treatment system system. I guess this helped very much to lower the pH. See the graphs below.

Trichloroisocyanuric Acid adding over time

As a result of adding Muriatic acid and Trichloro acid the following pH diagram resulted. The oscillating graph in the middle is caused by the inaccuracy of the test set. Only on March 22 the pH started to drop.

pH over time

When the pH came down the copper concentration could be measured more precisely, as with a high pH you can't measure the copper. The copper concentration should be above 0.4 ppm. The copper concentration is shown in below diagram.

Copper concentration over time in ppm
This shows that the system is now working well. On a weekly basis I have to measure pH and copper and fine tune the system, determining the ionizing, oxidizing and CO2 times.

Another important factor is mechanical filtering, using a pump and filter. These were installed already from the beginning when the pool was built. It will remove dead insects, leaves, hair and other debris, from the water coming from the skimmers, but not (all) the algae. And of course the pump is necessary for the EcoSmarte system to work.


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