What is The Difference Between Powder and Liquid Chlorine?

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Many new and veteran pool owners alike ask what the difference is between liquid chlorine and powder chlorine? They are not sure which is best to use and what is going to be more effective at keeping the pool clean and sanitized. There will also be a surprising amount of conflicting information on the internet depending on where you look.

The truth is, there are pros and cons to using either liquid or powder chlorine. What really should be the determining factor is what is going to be best for your pool, your budget and your equipment.


Chlorine : The Basics

Chlorine is the chemical that most pool owners isr as a way to sanitize their pool. Chlortine is widely used by pool owners to kill bacteria and algae in their pool making it clean and safe to swim in.

Chlorine is produced the electrolysis in saltwater pools so despite many website claiming saltwater pools are chlorine free; they aren’t!

Chlorine is an unstable chemical. It will degrade and breakdown over time, especially when exposed to the sun’s UV rays. This is why you are advised to test your water and administer chlorine regularly.

Lastly and importantly, chlorine is a hazardous chemical and great care should be used when hadling it. It is best advised to use protective gloves and goggles whenever handling chlorine, powder or liquid.


Liquid Chlorine

Liquid chlorine is made by bubbling the gas form of chlorine through caustic soda. Liquid chlorine has a pH of 13 and can be administered to a pool directly into the water. It is mostly used in commercial environments such as leisure centres as it can be administered in bulk from large drums.

Smaller, domestic pools, you will find that the cost outweighs it’s performance. Due to it’s high pH, you need to balance the pH back to a normal level (between 7.2-7.4). Liquid chlorine is highly corrosive and can lead to damage of your pool or equipment if great care isn’t taken.


Powder Chlorine

Powdered chlorine is the most typical form of chlorine used in a domestic pool environment. It is typically only slightly more expensive than liquid chlorine but it is much easier to use and has a lower pH, therefore has less impact on your pool’s balance when used.

There are three types of powder chlorine you can purchase:

Lithium Hypochlorite – Lithium has only 35% chlorine and it’s pH is high at around 11. This means that you will require more acid to balance your pool water. This is very rarely seen in the UK market however is good for use with liner pools as it dissolves very fast so it has less chance of bleaching the pattern in your lining.

Di-Chlor – This powder has a low pH of 7 so you won’t have to add much if any pH regulator when dosing. It dissolves quickly and gets to work straight away. It contains approximately 62% chlorine so can be used as a shock chlorine however there are cheaper alternatives if using in this application but handy to know in a pinch.

Calcium Hypochlorine – Calcium is by far the most popular powder chlorine in the UK as it is the most cost effective. It contains approximately 65% chlorine and has a pH of 12. Although this will require you to add acid to balance your pool, it is cheap to purchase over the alternatives. Proper care does need to be used when handling calcium hypochlorite as it is unstable and the fumes it can emit can be dangerous.


Making Your Choice

Your decision will likely be a based on a combination of your competency, budget and the equipment you have in your pool. Gram for gram liquid chlorine is the cheapest option however the associated costs of balancing and the potential cost of mistakes can be costly. Powdered chlorine in a domestic environment is by far the safest and cheapest option. If you are in a commercial environment, you are likely to have a chlorine dosing system which requires liquid chlorine and therefore this should be your choice.


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