Questions regarding CH test and if Yel/MstrdStock SLAM is appropriate for my pool condition

[abfabsabs]

Hi all,

First question is CH test. In the Extended Test directions (Calcium Hardness - Trouble Free Pool) it says to add R-0012 one drop at a time "until the color changes to something more or less blue". Mine goes more or less clear at about 40 drops, and starts to take on the faintest hint of blue at about 50 drops. Am I dealing with fading endpoint, or should I take my reading at the point when it first turns clear?

Second question is about which shock level I should use. I'd been dealing with a lot of yellowish gritty silt-like substance along the walls and floor of my pool, and especially in the crevices where the wedding cake stairs meet the walls. Thanks to a comment by @mknauss on somebody else's topic, it finally occurred to me that I'd probably been keeping the chlorine levels at just the right PPM to keep algae only "sort of" at bay. I've been getting professional pool service once a week, but my pool condition kept getting worse, so I finally decided to get involved. Got a Taylor test kit, Pool Math app, and started SLAMming Thursday of last week. It's only been 5 days, and my pool already looks significantly better, so that tells me it was probably algae that I intercepted before it became a major problem. But there are still trouble areas around the stairs and in the skimmer openings. I've been using the 16 PPM liquid chlorine SLAM level recommended for my CYA 41 PPM, but then followed a thread and came across this chart: Chlorine/CYA Chart which suggests if you're dealing with yellow or mustard algae, that you should use a chlorine shock level of 24 PPM for my 41 PPM CYA. Based on the photos I've provided, is the 24 PPM Yel/MstrdShock value appropriate for my pool's condition, or is that only meant for more extreme cases of algae?

Thanks for your insights!

 

[mknauss]

At that level of CH, time to drain and refill.

 

[abfabsabs]

I also wanted to add that, before I got hands-on involved in my pool chemistry, my pool service guy added a copper algaecide and my partner also added PoolRx, which I understand is also a copper-based algaecide. In addition to that, in late April, our well tank sprang a leak from corrosion inside. We promptly got it replaced with a galvanized tank, but those are three likely sources of metals (iron & copper) in our pool water. Any suggestions on how to remove metals (& stains) that would be appreciated as well. Thanks!

 

[abfabsabs]

At that level of CH, time to drain and refill.

Thanks for this suggestion. I've read on this site that fresh plaster sometimes can cause high CH readings, and high FC levels may also affect the reading, so I will mention that my plaster is only 6 months old and I've been keeping my FC at 24 PPM for the last 36 hours to combat an algae onset that became evident in late April when I started heating the pool to 82 F.

If it's common for fresh plaster to result in high CH readings while it cures, is it expected that it eventually rights itself, or do all owners of newly-plastered pools eventually end up draining and refilling once the plaster's cured to get back to ideal CH levels? We are currently in the midst of another drought in CA, so I want to be mindful of my water consumption.

That said, our water that we initially filled the pool with after replastering in Nov 2020 is extremely hard, but we did just have a whole home water softening system installed earlier this month. Would it suffice to continue topping off our pool from a hose sourced with softened water and reduce the CH gradually, or do you think it's critical enough to get the CH down immediately by draining and replacing some water?

 

[mknauss]

Fresh plaster will not raise CH much, if at all. If chemistry is well managed. The calcium comes from your fill water (used due to evaporation) or solid chlorine products with calcium (calcium hypochlorite). CH testing is not effected by SLAM level FC.

Getting the CH down is an aesthetic issue. Scale will begin to form first at the water line and then on general pool surfaces at the level of CH you are reporting.

 

[abfabsabs]

Fresh plaster will not raise CH much, if at all. If chemistry is well managed. The calcium comes from your fill water (used due to evaporation) or solid chlorine products with calcium (calcium hypochlorite). CH testing is not effected by SLAM level FC.

Getting the CH down is an aesthetic issue. Scale will begin to form first at the water line and then on general pool surfaces at the level of CH you are reporting.

Thank you. My pool guy HAD been using trichlor tablets in a floater along with liquid chlorine, but I've asked him to stop. I'm exclusively using liquid chlorine, granulated CYA kept at 40 PPM, and muriatic acid now. If we're only topping off the pool with softened water and have no more sources of calcium in solid chlorine products, do you expect that my CH figures should gradually reduce on their own, or do you still recommend a water replacement to accelerate a return to ideal levels? I see no scaling yet, but I've also been adjusting the pH down to 7.2 every day in an attempt to reduce my TA. My saturation index is about 1.

 

[mknauss]

Only water loss you will have to lower your CH using softened water is splashout and backwash of your sand filter. So if you wish to manage your chemistry (you must get your CSI to 0.3 at the highest) ) without doing a partial drain and refill with soft water, you can chance it.