Rust color smudge like stain suddenly on the bottom of my pool that doesn’t brush off

[asardam32]

Rust color smudge like stain suddenly on the bottom of my pool that doesn’t brush off.
I have a fiberglass pool.
CHLORINE 4
PH 7.5
ALKALINITY 150
STABILIZER 40
CALCIUM 700
The calcium has been high but the only solution I’ve seen is to drain in order to lower. For some reason my calcium is always high year after year. Any suggestions as to the stain or calcium?

 

[PoolStored]

For the stain, follow the stain guide:

Stains in Your Pool

The stained pool is beyond embarrassing. Our in-depth Guide to remove stains in your pool will help you to remove the stains and prevent them in the future.

www.troublefreepool.com

For the calcium, test your fill water, it is likely high. The only way to reduce calcium is to replace water. See "no drain water exchange" in the draining wiki link below.
You might consider using a water softener on your fill line to reduce the CH content of your fill water. Do you have an autofill?

Draining - Further Reading

www.troublefreepool.com