Ascorbic acid treatment

If you can’t replace the metal laden water with fresh water, then you have to be really careful to keep the pH and TA low. You need to keep the TA closer to 50-60ppm and the pH below 7.4 as well as add the maintenance doses of sequestering agent. Unfortunately that means you’ll be using more acid than normal to keep the pH/TA in check and the money will start to rack up with all the sequestering agent you’ll use. So only you can determine if the extra cost is worth it with respects to what it would cost to get fresh water into the pool.

Diverting rain water into the pool can help as long as the collection process is clean (roof water tends to be pretty dirty). Any time you lower the pool water level an inch or two and let rain fill it back up will only help to minimize metal contamination.