Dirt Scale

[JConant]

Hello -
Live in AZ, had a new pool put in 11 months ago. Last week after a bad storm I noticed a lot of dirt on the bottom and some on the walls, which is no surprise. What was a surprise is that I couldn’t scrub it off. After some research I learned this could be Dirt Scale which is dirt that has been trapped under a layer of calcium.
I read that dropping the PH and raising chlorine and lots of scrubbing will remove it and it has helped, but very slowly. Am I on the right track? Any other thought or ideas. Thank you

 

[BenB]

Hi! Welcome to the forum.

May we ask how you are currently testing your water? And you are using liquid chlorine if your signature is right?

What was it that led you to the "dirt scale" conclusion as opposed to some black algae or other type of growth?

Do you have any photos?

 

[JConant]

I use AquaCheck 7 strips to test the water
I use liquid chlorine and pucks as needed
In checking some other forums, “dirt scale” is something that came up and made sense. This literally happened overnight

 

[mknauss]

Any copper algaecides or other copper containing products used in this pool?

 

[BenB]

If it happened overnight I would likely think it's a more straightforward algae bloom - they grow invisibly until they reach a critical mass and then BOOM visible algae.

Anything related to scaling or calcium in a pool is very gradual and takes place over an extended period of time. That's why I am skeptical of the notion that it could be any kind of dirt physically protected by a layer of calcium.

Others will say it in greater detail, but around here we are highly skeptical of 'guess strips' which are shown to be very inaccurate. They also suggest chlorine levels that are lower than what is likely needed, so you may have been dosing to what it suggests and been given a false sense of security. It is quite likely that you have been running your chlorine levels too low such that stuff was able to grow and given the mid-summer heat, this could have happened very quickly.

I would strongly recommend getting a good test kit for your water testing. I've put a link below to a comparison of the 2 that are most recommended here. I use the TF-100 and it has paid for itself 10 times over at this point - I've never bought a single product from a pool store except for acid because following the TFP recommendations mean I never got myself into a spiral of adding contradictory and unnecessary chemicals by relying on others to do my testing for me.
Test Kits Compared

 

[JConant]

Any copper algaecides or other copper containing products used in this pool?

No algaecides at all, no other copper containing products used either

 

[BenB]

Previous comment stands re: getting a good test kit. Just for giggles though, can you share your current guess as to what these are based on what you have right now?

FC/TC:
CC:
pH:
TA:
CH:
CYA:

 

[JConant]

Previous comment stands re: getting a good test kit. Just for giggles though, can you share your current guess as to what these are based on what you have right now?

FC/TC: 3/5
CC: 3
pH: 7
TA: 120
CH: 5
CYA: 125

 

[BenB]

FC/TC: 3/5
CC: 3
pH: 7
TA: 120
CH: 5
CYA: 125

Oh yeah, my money is firmly on algae

*All this is based on an assumption that the numbers are accurate. But they absolutely aren't. So this all could turn out to be wrong. Only a good test kit can confirm your numbers*

CC of 3 means lots of nasties in the water.

CH of 5 is impossible unless you filled your entire pool with water from a water softener and even then a precision of 5ppm is kinda funny.

Your CYA is about triple what it should be. Consequently, your chlorine is abouta third of what it should be. Fire CYA 120 you're looking at needing 12-15 FC, but really that's not sustainable.

Plan to drain and refill or exchange 75%+ of your water. Then you'll need to SLAM.

Recommended Levels
SLAM Process
FC/CYA Levels

 

[JConant]

Oh yeah, my money is firmly on algae

*All this is based on an assumption that the numbers are accurate. But they absolutely aren't. So this all could turn out to be wrong. Only a good test kit can confirm your numbers*

CC of 3 means lots of nasties in the water.

CH of 5 is impossible unless you filled your entire pool with water from a water softener and even then a precision of 5ppm is kinda funny.

Your CYA is about triple what it should be. Consequently, your chlorine is abouta third of what it should be. Fire CYA 120 you're looking at needing 12-15 FC, but really that's not sustainable.

Plan to drain and refill or exchange 75%+ of your water. Then you'll need to SLAM.

Recommended Levels
SLAM Process
FC/CYA Levels

Thanks, had a pool company come out and told me it’s yellow algae. Levels were “spot on” so I must’ve made a mistake in my last response. Apparently this algae growth can happen after a dust storm in which the wind carries large amounts of pollen that causes the algae growth, regardless of chemical levels. Cleaning it up with a wire brush, Algaecide, 4lbs of shock and some phosphate reducer as that was also a bit high. Should be back to crystal clear in about 36hrs. Appreciate the feedback.

 

[BenB]

Cleaning it up with a wire brush, Algaecide, 4lbs of shock and some phosphate reducer as that was also a bit high. Should be back to crystal clear in about 36hrs. Appreciate the feedback.

I really wish you hadn't bought all that. The algaecide is at best, expensive chlorine substitute and at worst will put metals in your water that will cause stains and turn blonde hair blue, the phosphate remover is expensive and entirely unnecessary, and just chucking in some shock and hoping for the best is not guaranteeing that the problem won't come back.

How did the pool company test your water? Did they share their results with you? If you have algae your levels are NOT spot on.

I really fear you're not doing yourself any favors here.

It's your pool, you're free to do whatever you want with it, but thousands of users of this site, which is not selling anything, will confirm that most pool companies don't know what they're talking about, use outdated methods, and are happy to keep you in a spiral because they can continue to sell you chemicals week after week.

Good luck. Please consider reviewing the materials on the site, getting a real test kit that will give accurate and consistent results, and you'll be guaranteed the results that you're hoping for with this quick fix.

 

[mknauss]

Let's hope that the algaecide was not sodium bromide. Do you have the container?