I have a large swimming pool and over the years I have learned from mistakes. I would like to share what I have learned. I don't use salt water and electrolysis to generate chlorine. This is a traditional unheated pool and I never swap the water because it is a liner pool.
Here some tricks on how to maintain fairly healthy a low chlorine pool environment.
Companies making pool chemicals do not have to declare what is inside. You will often find products that have detailed mixing instructions but it says nowhere on the
bottle what is inside. Don't buy any of these products. Don't put unknown chemicals into your pool water. Your body absorbs pool chemicals through the skin. If you care
what is in your food then you should care what is in your pool water.
Don't use clarifier. Clarifier is an Al3+ salt and it destroys the zeta-potential of water. It is toxic to all cellular life and causes small debris to clump together. It is used in small quantities in drinking water but in pool water it can quickly reach dangerous levels. Dissolved Al3+ salts stay over years in the water. Water is the basis of life as we know it and Al3+ disrupts this life and can make you slowly sick in very strange ways. The symptoms are tiredness, low energy and often sick. Al3+ ions causes strokes and micro-strokes if larger amounts make through the skin into your body.
Al3+ ions can absorbed into your body through your skin. You don't have to swallow pool water to be exposed. Many people know that aluminum is everywhere and therefore our body should be able to handle it. The aluminum in the environment is aluminum oxide. It's in the soil and in clay. It does not dissolve in water. Aluminum ions (Al3+) are something else and they dissolve easily in water.
The main priciple of my pool philosopy is: Keep algae in check with simple chemicals and just add a bit of chlorine.
What I use is:
A spoon full of copper sulfate and a few spoon full of borax for algae and PH control. Note that both of those salts stay in the water forever. For the next season you have
to add less if you still have mostly old water in the pool. I use a table spoon of copper sulfate per 100000 liter of water and a cup of borax powder per 100000 liter of water.
Naturally the pool water will tend to go acidic over time. This is mostly due to rain water, microorganisms and the decomposition of chlorine sanitizer under UV light. All shift the PH towards acidic. I add a bit of borax when the PH falls below 7.5. Borax is an anti fungal and highly alkaline but it is thought to be a non toxic mineral necessary for human life (in very small quantities).
If you need to make large PH adjustments then use baking soda instead of borax. In 15 years of pool maintenance I never had to adjust the PH towards sour. It always drifts
by itself from 7.5 to lower values.
I use sodium hypochlroide (bleach) or calcium hypochloride (chlorine powder) as a chlorine sanitizer. I avoid Trichloro-s-triazinetrione (chlorine pucks, aka trichloroisocyanuric acid). Calcium hypochloride makes in water hypochlorous acid and this decomposes then into hydrochloric acid (HCl) and oxygen under strong uv light or it chlorinates organic matter.
Safrax tablets (chlorine dioxide) is also a great sanitizer but chlorine dioxide breaks down easily in the presence of sun light. You need to apply it over night and some of it may disappear
when the sun shines on the pool the next day. Safrax is expensive for a large pool but you can use calcium hypochloride and safrax at the same time or alternate. I find that alternating is the best. Hypochlorous acid as generated by calcium hypochloride and chlorine dioxide as generated by safrax work in different way on microorganisms. Alternating once in a while does not bread resistant strains and this way you can keep the sanitizer levels low.
