Gritty sand stuck to plaster and iron staining

[philly_b]

Hi.

Just had the pool opened a week ago. The pool company shocked the pool and the water looks great. However, the are two problems. I’m not sure whether they’re independent, or not.

• Iron staining (confirmed with a vit C tablet)

I assume this is from our well water, combined with the high shock FC. We had a leak at the end of last season from one of the bottom drains, so after solving the leak we slowly filled from the well. I’ve ordered 5lbs of AA which will be employed once the FC level drops. I’ll also be using sequestrate for the future.​

• Gritty “sand” that’s tightly stuck to the plaster.

Not sure whether this is coming from the well water, or elsewhere. We’ve had some weird weather recently, including a nearby tornado. The well water does go through a filter before it gets to the hose. Perhaps I should use a higher-grade filter (might catch iron as well as more grit)? The only way I’ve been able to get rid of it is using brute force. Wire brush or a drywall filler knife. It seems similar to this old thread: Gritty plaster ​

Does anyone have experience with such a problem?​

Thanks in advance for your help

Water temp = 76
pH = 7.2
TA = 70
CYA = 40
FC = too high to treat with AA, but dropping.

 

[mknauss]

The thread you referenced sounded like it was scale buildup. Have you scraped off some of what you have and tested it with acid?

 

[YippeeSkippy]

See if you can chip off a piece and pour a smidgen of muriatic acid on it (like in the grass or someplace safe). If it fizzles that tells us its calcium. Which means you probably have scale build up.

Calcium Scaling

Calcium scale on your pool is something we all want to avoid. With some elbow grease and a pumice stone for pools we can help you remove this eyesore.

www.troublefreepool.com

Maddie

 

[philly_b]

Thanks.
I'll do that when I get home, but isn't calcium scale white?
This is distinct, sandy colored grains.

 

[mknauss]

Do you have iron in your water? Your calcium may be stained with iron.

 

[philly_b]

I believe you're completely correct.
A clear bubbling reaction to muriatic acid indicates calcium, and yes I have iron staining on the pool wall (and obviously in my calcium deposits).

FC is still too high for ascorbic acid.
I tested pH again. It's still indicating 7.2.
I do have a new batch of Taylor chemical en route, as my current stock might have aged?

I'm just off to read up on calcium scale removal (from Maddie's link).

 

[philly_b]

Hm. With the AA treatment for the iron staining, the CSI will approach -0.8, so my first approach will be elbow grease. If that doesn't work, then an acid wash and a few trucks of water might be the best solution (followed by better CSI maintenance).

 

[philly_b]

New chemicals arrived today.
FC = 8
pH=6.8
TA=50
CH=150
CYA=35
CSI=-0.6

I assume I wait for the FC to drop to near zero, then
Add AA to treat iron staining, then
Use the opportunity of the low CSI to try to remove the calcium scale, then
Bring the CSI back to near zero.

I'm thinking add bleach for FC, increase TA to 70, get CH to 250, then tweak pH.

Is this the appropriate order?