I was able to determine the stains in my pool are indeed metal...the local pool store gave me a small bag of Ascorbic Acid which I put in a sock and held it against a stain. It worked well - so well that I ended up dumping 2kg of it per the instructions found on TFP. (Sourced it from Amazon) Prior to the treatment, I let FC drop to 1-2 and lowered PH to 7.5. My CYA is quite low (~20) from the winter rains - I'll rebalance pool chemistry once this treatment is complete.
There was a noticeable improvement in the staining, but at least another course will be necessary.
(We purchased the home ~2.5 yrs ago. I have extensive staining in the pool from years of neglect. I believe the source of the stain is from rusting/deteriating galvanized piping in the home (water source) as well as a failed pool heater. The CYA level was in excess of a 1000 but is now under control - I don't think this pool had its water drained for decades.
Here is the question:
My intention was to use a Jack's...but the local store doesn't carry it. Unbeknownst to me, they dropped Jack's line and now use Natures Metalfree product. I needed something quickly (already dumped in the Asorbic Acid), so I picked up a 1L bottle. Per the instructions, I need to add some each week - this stuff is expensive.
I know that I need a sequestrant/chleating solution, but adding some each week seems excessive.
1. Should I try to source Jack's prior to treating the stains adding another 2kG of Ascorbic Acid?
2. Will I need to add Jack's every week? Seems expensive.
3. Should I look for a better HEDP? Which Jacks would be best?
4. Will the filter ever remove the chelated metals? (If the stains come back, does that mean my filter cartridge is bad?)