Aluminium sulphate, also known as Alum, is a water-soluble chemical with multiple uses. Have you heard of it? It’s a coagulating agent that is used in waste-water treatment plants and some manufacturing processes.
We’re interested to know why it’s used in swimming pools.
Understanding Aluminium Sulphate
Aluminium sulphate possesses a strong positive charge which naturally attracts matter with negative charges in your pool. Pathogens, phosphates, pollens, and other undesirable bodies suspended in your swimming pool are drawn to the alum particles which binds them together.
These clumps are easier to see and remove. It’s that simple.
When do I Need Alum?
Many pool owners make use of alum during the pollen season when they look out over what should be a beautiful blue pool and notice a film of yellow or orange particles. Pollen can be notoriously difficult to get rid of!
Pools that have been left to their own devices and have a swamp-like appearance will also benefit from a dose of alum without having to be drained and refilled.
While it’s a quick job to scoop out leaves or dead frogs (it happens!) it can be tricky to remove small particles that would slip through the net or even through the sand filter.
This is when you’d use alum.
After skimming and brushing the pool, ensure that the chemicals are as balanced as possible, and then sprinkle the aluminium sulphate over the surface of the water. Check the instructions for dosage.
Run your filtration system for a couple of hours, and then turn it off and let this clever little chemical do its job. After a few hours – usually, 12 – 24 hours depending on the condition of the swimming pool, the alum and debris will have formed clumps that sink to the bottom of the pool.
Thereafter, set your pump on waste and vacuum up the debris and you should have a wonderfully clear pool minus all those little floating bits.
As with any pool chemical, exercise caution and make sure that you’re using the correct dosage for the size of your pool. If in doubt, then pop into your local Pool Spa outlet and chat with one of our friendly and knowledgeable team. We’d be glad to help.