SLAM Day 7 - getting anxious of stains and order of chemicals to fix

[Tass]

I started the SLAM of my pool and it's been working great so far: the pool is improving in clarity day by day and it's been holding the FC fairly well and even overnight somewhat but it still is not clear through so I'm still doing it.

I have noticed over the last week though stains forming on the side of my fiberglass pool, which I believe I have determined them to be due to metals/low calcium hardness. The latest log is from this morning which was only 75 ppm (all my logs are shared in PoolMath). I know I have seen that CH may not matter as much for fiberglass, especially newer ones, but mine is fairly old (even the owner wasn't certain, maybe 30 yrs), so I assume that those stains are due to that.

I am attaching some pictures to get a second opinion on whether these stains are due to metals/low calcium and the steps to get them figured out.

My thought process is:
a) even though SLAM is ongoing and I'm keeping FC in SLAM level along with vacuuming/brushing etc, I should still add chemicals to deal with the stains. Is that advisable?
b) I have found Calcium Chloride anti-ice (proven to be 94% that) and a HTH sequestrant which I was going to try. Should I try to increase hardness first or use the sequestrant first and wait and see?

Any advice is appreciated.

Thank you in advance!

 

[Texas Splash]

That is an older model for sure. The discoloration could either be from iron in the local water or perhaps organic staining over time. First thing I would do is take a Vitamin C tablet and rub it directly on a stained area. If the Vitamin C removes the stain, it's iron. If that doesn't work, you can try rubbing a stained area with a chlorine tablet to see if it's organic. Let us know how it goes.

 

[Tass]

That is an older model for sure. The discoloration could either be from iron in the local water or perhaps organic staining over time. First thing I would do is take a Vitamin C tablet and rub it directly on a stained area. If the Vitamin C removes the stain, it's iron. If that doesn't work, you can try rubbing a stained area with a chlorine tablet to see if it's organic. Let us know how it goes.

Thank you, I will go buy some Vitamin C to test it out with the stain. In the picture there are some "black" spots as well which I believe--from what I've seen--are indications of cobalt leeching or something like that. That's why I was thinking I need a metal remover on top of that.

 

[Bperry]

Thank you, I will go buy some Vitamin C to test it out with the stain. In the picture there are some "black" spots as well which I believe--from what I've seen--are indications of cobalt leeching or something like that. That's why I was thinking I need a metal remover on top of that.

You should confirm metals in the water before doing anything to treat it.