How do I treat and prevent hot tub foaming?

What causes foam in a hot tub?

There are a number of things that can cause foam in your hot tub. The most likely culprits are ....

cosmetics - makeup; body oils and lotions and hair products, particularly hair gel.
suncream
washing detergent and, particularly, fabric conditioner left on swimwear
filter cleaner that hasn't been fully rinsed from the filter
pipe cleaner (biofilm remover) that hasn't been adequately flushed from the tub prior to re-filling
household cleaner - only ever use specialist hot tub cleaners om the shell of your hot tub or your cover, they are designed not to foam.

Foaming can also be aggravated and enhanced by a high pH level.

Also, over time and use the water will absorb and retain dissolved 'stuff' - referred to as Total Dissolved Solids or TDS - and sometimes the water just gets too old and can't absorb any more contanimants. At this point it will foam and there's nothing that you can do about it other than change the water.

How to treat foaming water

First of all consider if the water might just be too old. If your water has been in the tub for more that 3 months and it is foaming then you need to change it.

Assuming that elderly water isn't the cause of your problem then it might seem odd but your first action should be to use a hot tub shock. A shock will remove some of the water contaminants and might just solve the problem.

In combination with using a shock, and if you have the time and inclination, you can also try scoping out the foam as it develops.

If a shock doesn't work after a day or two then you can use a hot tub anti-foam product, following the instructions on the bottle. If you use an anti-foam it will solve the problem but, unfortunately, it will also make the water look quite dull and the water will definitely lose it's sparkle. The dissolved contaminants will also remain in the water adding to the Total Dissolved Solids and meaning that the water will need to be changed sooner. So anti-foam products are best avoided if at all possible.

It also goes without saying that you should think very carefully about what caused the foam in the first place and so avoid it happening again in the future!