Can you still swim in a pool with high alkalinity?

Yes, It will just make your skin itch

Answer:

Lower Your Pool Alkalinity

You want to run your pool water alkalinity level between 80-100ppm, not up to 150 as some may suggest. Most pools guys get their info. on how to balance pools from your local water company. Yes, this is correct. It's called the Langelier Index, which was originally designed for public water systems. This index was never intended for pools.

In the 1950's, when pools started to come into the mainstream, this was the only index available, so it was used to balance pools and hot tubs.

The Hamilton Index, which I use, is much more pool-friendly and is specifically designed for pools. It takes into consideration acid rain, drag-off, heat, the sun, organic and inorganic matter in the pool, etc...

While I don't completely agree with the Hamilton Index, it is much closer to how a pool should be balanced and will save you much time and money in the long run.

Higher alkalinity levels (120ppm or above) can be reduced using pool acid. There are mainly two types of acid:

liquid hydrochloric acid (muriatic acid)

dry acid (sodium bisulphate)

Take care when using acid because it may affect your pH.

While your filtration system is off and the water is motionless, stand in the deep end and slowly add (don't dump the product or go too fast), the pool acid,

or alkalinity minus if you wish, into the pool. Please remember to use goggles and heavy rubber gloves. If you spill any acid on your skin, it will probably eat through 3 layers of skin before you can wash it off. Remember, safety first.

Allow the water to sit for 2-3 hours, then fully circulate, usually 4-6 hours, then re-test your pool's alkalinity balance.

Using the proper chemicals and proper techniques will allow for better results.

You can go to the link below for a full chart on lowering your alkalinity.