As a hot tub owner, you may have noticed there’s different products for hot tub chemicals and swimming pool chemicals. A quick look at the labels of these chemicals may seem to indicate that they’re actually the same. If that’s the case, and you own both a hot tub and a swimming pool, why buy two different sets of products? Are hot tub and pool chemicals the same? In this article, we’ll take a closer look at these chemicals and explain why they aren’t interchangeable.
As mentioned in the introduction of this article, at first glance, it appears that hot tub and swimming pool chemicals are the same. Chlorine sanitizers contain chlorine. pH increasers contain soda ash and pH decreasers contain muriatic acid. So how are hot tub chemicals and swimming pool chemicals any different from each other? If you read the labels of these products a bit closer, you’ll realize that the concentrations of the active ingredients in these additives are quite different. For reasons we’ll go into later in this article, the concentrations of swimming pool chemicals are much higher than those found in hot tub chemicals. Because of this, it’s not a good idea to mix the two up.
One of the main reasons that swimming pool chemicals are much more concentrated than hot tub chemicals is the amount of water found in a swimming pool compared with that in a hot tub. A hot tub may hold around 2000 litres whereas a swimming pool can hold as much as six times that amount. For this reason, swimming pool chemicals need to be much more strongly concentrated to be effective in changing the water chemistry. Adding highly concentrated swimming pool chemicals into the small volume of water found in a hot tub can irreversibly change the water chemistry meaning you’ll have to empty and refill the tub to regain control.
In higher temperatures, chemical reactions are much more vigorous and happen much more quickly than at lower temperatures. Of course, the temperature of the water in your hot tub is much higher than that found in the swimming pool. Most hot tubs run around 40 degrees Celsius, whereas swimming pools will typically max out at 30 degrees. Add the higher temperature of hot tub water with the higher concentrations of swimming pool chemicals and you’ll see wild fluctuations in the water chemistry levels that may become impossible to manage. On the other hand, if you add hot tub chemicals, with their lower concentrations, into relatively cool pool water, you may see no effect whatsoever.
Water circulation will also play a role in the rate of any chemical reactions. The faster the water circulates, the faster any reactions will take place and the more complete those reactions will become. Hot tub water jets are much more powerful than those normally found in swimming pools. Added to the fact that there’s a lot less water to move around, chemical reactions will naturally take place faster in a hot tub than in a swimming pool. By adding highly concentrated swimming pool chemicals into a hot tub, the reactions will become even more vigorous and may end up radically altering the water chemistry.
Water evaporation will naturally concentrate the amount of chemicals found in the remaining water. Because of the hot tub’s relatively high temperatures, strong water jets and lower volume of water, evaporation plays a larger role in concentrating the remaining chemicals in a hot tub compared with a swimming pool. When combined with highly concentrated swimming pool chemicals, this can lead to irrevocably imbalanced water chemistry.
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