New to me pool

[Dealwitme]

I've just purchased a new house with a pool. Far as maintaining the pool, I'm relying on info my local pool store telling me. I've found this forum and been browsing threads to help me out. The pool is a 25k gallon inground salt water pool.

[Watermom]

Welcome to the Pool Forum! Did you have any questions you needed help with?

[Dealwitme]

We'll I did but I believe I have everything handled now. I had a problem with algae blooming and low level of chlorine. However, after changing my sand, shocking back it back and defender, all is stable in my pool. The water is crystal clear.

[Watermom]

Glad it is working out for you. I will tell you that it really isn't necessary to change out your sand. Many of us use the same sand for years and years and years as it doesn't really 'wear out.' Sometimes you do need to top it off but seldom change it unless you have been using Baquacil or something like that.

I have no idea what 'defender' is. What are the ingredients?