Which one is correct?
If I write in a general sense...

Bad things that can happen in A swimming pool, how bad is this? Do you really need to worry about dangerous chemicals when you take that next dive?

Bad things that can happen in THE swimming pool, how bad is this? Do you really need to worry about dangerous chemicals when you take that next dive?

Question

Which one is correct?
If I write in  a general sense...

Bad things that can happen  in A swimming pool, how bad is this? Do you really need to worry about dangerous  chemicals when you take that next dive?

Bad things that can happen  in THE swimming pool, how bad is this? Do you really need to worry about dangerous  chemicals when you take that next dive?

Answer

Gamarjoba tbilisidan!

"...... a swimming pool" means any swimming pool.

"..... the swimming pool" means we both know which swimming pool. It doesn't mean ANY swimming pool.

Answer

You could use either A or THE. There is little difference between them, however you are more likely referring to a specific swimming pool when you use THE.