Hi all, just wanted to relate my experience with some metal stains.
I ahve a ~16K IG plaster with french gray plaster (diamondbrite). I built my pool about 3 years ago, and my fill water has some copper and iron in it. I was recently disappointed to notice some pretty heavy stains, that I diagnosed using test from the forum as metal staining.
I bought some bulk ascorbic acid off amazon, a couple of bottles of jacks magic purple, and a couple of the large CULator packs.
so one saturday I started off (actually thrusday night I technically started by turning off my SWG and dropping my PH to 7.2 using my intellichem) and dropped a couple of pounds of AA in, it was powder so I spread it around the pool.
It was amazing to see the heavier stains start to just fade away. I added more after a few hours (probably too much at this point) and let it circulate overnight.
The next morning I was thrilled to see the plaster looked like new. wow.
So after another day I started to carefully bring the CL back up, slowly using my bleach and test kit, watching the PH as I did so. at this point we got a serious thunderstorm that overflowed the pool (about 4" of rain in as many hours).
Afterwards I drained the pool back down to normal levels, and checked the salt, and it was low so I added a bag. I also added the sequestrant and put the culator egg in the pump basket.
uh oh... as soon as I added the salt, something happenned. The pool turned a swampy green-brown and got very cloudy. I ran some tests and the cl was back down to zero. I had somewhat overdosed on the sequestrant i think 2 bottles in a ~16K pool and the ph was around 7.4. hmmm. well not wanting to raise the ph any more for fear of the metal coming out of solution, I held off on any more chlorine and added acid. Then after a few hours tested and dosed cl up to normal (not shock) levels. my normal reaction to any cloudiness is to SLAM the pool, but I couldnt do that for fear of precipitating the metals back onto the plaster... so I decided to just shoot for maintaining the CL at normal levels and watch/dose the PH closely to keep it around 7.2.
this approach took FOREVER. for the next two weeks I just opened can after can of POP (pool owner patience) and stuck with the plan. I was testing and getting results indicating plenty of CC, but just kept at it with small doses of bleach whenever it was indicated. (I had established through testing over the past couple of years a corellation between indicated ORP level on my intellichem and the FC level of the water, so I didnt have to use up all my chemicals... ) Then we had a week long trip to mexico and I put things on hold and kicked on the swg and let my intellichem maintain things while I was gone.
I got back after our trip and the pool was pretty much the same as I left it. I checked the culator packet and it was a dark brown. I swapped it for another new one.
Then I just kept on dosing with bleach up to normal levels as often as I could (avoiding shock or SLAM levels). After 18 gals of bleach and another weeks worth of POP, the pool has slowly come back to crystal clear. YAY!~
The only thing I did not expect was my poolskim (made of white PVC) had stained up brown something fierce, as well as my skimmer baskets and skimmer interiors. For these I made up a bucket of water and AA and washed them clean, blocked the skimmers and drained them using a shopvac and washed them down with a sponge and some of the AA loaded water from the bucket. everything returned to a nice bright white, and I rinsed and shop vacced the skimmers again before restoring normal circulation to them.
All in all the aftermath of the AA treatment was well worth it, but took MUCH longer than I thought it would (a month in total). The CUlator seemed to work as advertised too. I am thinking of keeping one in the pump basket at all times now to keep the metals in check.
I had a talk with an industrial chemist who said we could build a larger version of the culator packet and install it in the plumbing with appropriate bypasses and all, and am considering doing that. He says they do that sort of thing all the time, and he could point me to industrial suppliers for the polymer they use to remove metals from water streams. He did some back-of-the-napkin calculations and a volume of a gallon or so of the polymer would do me for a year or so and not cost very much at all (about the same as a culator packet ~65). the device to build might cost a hundred or two.