This is a pool water blog written by the engineering team at NanoSWIM in Bergen — practical water treatment guides rather than product announcements. If a question comes up often enough during a site visit, it usually ends up here.
Free chlorine is the disinfectant that is still working; combined chlorine is what is left after it reacts. Here is how to tell the two apart, and how to raise free chlorine without just adding more product.
A strong chlorine smell means too little free chlorine, not too much — it is chloramines building up, not chlorine itself. Here is why that happens and how to fix it.
Green pool water is algae, and algae only takes hold once free chlorine, circulation or pH has already given way. Here is what causes it and the order to fix it in.
Chlorine itself rarely irritates skin or eyes — chloramines and the drying effect of chlorinated water usually do. Here is what actually causes it, what the different symptoms mean, and what reduces it in practice.
No — a pool needs disinfection, not chlorine specifically. Here is what actually replaces it, and why a Norwegian public pool still cannot go to zero.
Nanobubbles are gas bubbles under roughly 200 nm that stay suspended for days. What that does in a pool loop, and what it does not.
A pool's running cost sits in six lines. Heat and ventilation usually dominate chemicals. Which lines you control, and where water treatment fits.
Most of a pool's energy goes to heating water and air, then pumps. Where the savings are, in the order worth trying, and what water treatment can and cannot do.
Backwash when the pressure gauge says so, not when the calendar does. How to clean sand, cartridge and DE filters, how to tell when it is time, and what no water treatment can replace.
Discover how nanobubbles — microscopic gas-filled spheres — are revolutionising water treatment without chemicals.
Chlorine has been the standard for pool disinfection for decades — but the tide is turning towards healthier, chemical-free alternatives.
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The articles above are grouped into six categories, and you can filter by any of them using the selector at the top of the list.
Two articles account for most of the traffic here, and they are the right place to start if you are new to this. Nanobubble Technology Explained covers how ultrafine bubbles transfer gas and drive oxidation. Why Chlorine-Free Pools Are the Future makes the case for moving away from chlorine, and is best read alongside our more sceptical comparison of the alternatives.
For short answers rather than long reads, the FAQ is faster. For evidence rather than argument, start with our reference: 85% less chlorine at a resort pool.
We do not run a mailing list, so there is nothing to sign up for and nothing to unsubscribe from later. New articles simply appear on this page. Bookmark it, or check back when you are working on a specification and want the current thinking.
If there is a topic you want covered — a pool water tips piece, a regulatory question, a comparison we have not written — tell us and we will put it on the list. Questions from operators are where most of these articles start.
Send it over. If it is a good question we will write it up properly, and either way you will get an answer from someone who works on these systems.