Can you solve the mystery!?

[Hisbestcatch]

Hi everyone!
Hoping you can solve this powder mystery. Pool has been filled since 10/2020 and the past 2 months we’ve noticed this fine white powder accumulate around the steps/sun shelf and bottom. It comes out of the filter as well (cartridge filter) when we clean it.
It feels very soft, powdery, super fine and sand like.
Pool store can’t figure it out, our Jandy rep didn’t know and I’ve googled my fingers raw! We vacuum it up and it just comes back. I’ve attached some photos. I’d appreciate any feedback!!
FC 5
CC 0
PH 7.6
TA 80
CH 425
CYA 60
Salt 3000
Temp 89
CSI -.020
CL industries Pebble

 

[JJ_Tex]

How close to the beach are you? Are you sure it is not sand?

 

[Hisbestcatch]

How close to the beach are you? Are you sure it is not sand?

We considered sand but we haven’t been to the beach since the pool was finished this past October. We are about 5 miles away. After we vacuum, it comes back. We also have a screen, I forgot to add that.

 

[JJ_Tex]

Hmm, any chance it could blow in or is your yard also sandy soil and people could track it in from there?

If it is not sand, I would next check for calcium. Can you collect some and pour a tiny bit of muriatic acid on it and see if it fizzles? If it does then it could be calcium.

 

[Hisbestcatch]

Hmm, any chance it could blow in or is your yard also sandy soil and people could track it in from there?

If it is not sand, I would next check for calcium. Can you collect some and pour a tiny bit of muriatic acid on it and see if it fizzles? If it does then it could be calcium.

We are surrounded by thick grass so it wouldn’t be from the yard. We enter the pool from the inside the house as well since it’s screened. We just collected some and did the Muriatic acid test and it did fizzle but when we tried some dirt as a comparison, it also fizzled. I got excited for a second! Hmm our calcium is also right where it needs to be and we’ve never had to add any additional. Tell me more about calcium doing that since you could be onto something! The amount that accumulates on the bottom and comes out of the filter it just so crazy! After vacuuming it up, takes a few days and it’s back.

 

[JJ_Tex]

With those numbers I would not think calcium either, but calcium does fizzle and would not do that if it was plaster or something else. Hoping some others will chime in with ideas. In the meantime, here is a similar thread I found if that offers any clues:

White deposits in pool

I am teying to know down the alkalinity with acid. In a week time its onli going down 10 ppm with acid. I add acid every other day to lower it. Thanks.

www.troublefreepool.com

 

[Hisbestcatch]

With those numbers I would not think calcium either, but calcium does fizzle and would not do that if it was plaster or something else. Hoping some others will chime in with ideas. In the meantime, here is a similar thread I found if that offers any clues:

White deposits in pool

I am teying to know down the alkalinity with acid. In a week time its onli going down 10 ppm with acid. I add acid every other day to lower it. Thanks.

www.troublefreepool.com

Thank you JJ_Tex! I also stumbled across that thread earlier and noticed that pool owner had a sand filter. It sounded so similar I had to double check that ours was indeed a cartridge.

 

[duraleigh]

It can be hardly anything else but calcium precipitation. What is the CH of your fill water?

 

[Hisbestcatch]

It can be hardly anything else but calcium precipitation. What is the CH of your fill water?

I’m going to check this first thing in the morning and post back to you!.....

 

[Hisbestcatch]

It can be hardly anything else but calcium precipitation. What is the CH of your fill water?

Just tested our hose bib that we use to add water. It tested at 75 CH

 

[JJ_Tex]

I still think the most likely culprits are calcium or sand. Since sand seems more unlikely of the two, I would aim to keep your CSI a bit more negative at around -0.3 or maybe even -0.6 for a month or so and see if that clears it up. The easiest way to do this would be through keeping your pH lower.

If that does not work, some other possibilities:
- Sand, its unlikely but could you have sand from your dirt being sucked in from a small suction side leak? Do any neighbors have similar issues where it could be blowing in?
- Someone adding something incorrect to the pool/filter. Any chance someone added DE or sand to the filter or any other mystery pool store potions that might offer some clues?

 

[Hisbestcatch]

I still think the most likely culprits are calcium or sand. Since sand seems more unlikely of the two, I would aim to keep your CSI a bit more negative at around -0.3 or maybe even -0.6 for a month or so and see if that clears it up. The easiest way to do this would be through keeping your pH lower.

If that does not work, some other possibilities:
- Sand, its unlikely but could you have sand from your dirt being sucked in from a small suction side leak? Do any neighbors have similar issues where it could be blowing in?
- Someone adding something incorrect to the pool/filter. Any chance someone added DE or sand to the filter or any other mystery pool store potions that might offer some clues?

Thank you! We will try lowering the PH a bit and see if that helps. It’s very unlikely to be any kind of sand and we checked the pools on each side of us and the problem doesn’t exist in theirs. It is also so powdery and fine. My husband the only one who has ever maintained our pool and we have never added any of the pool store potions etc they try and sell. We only follow the TFP recommendations and purchase all testing supplies through here. Our filter is “cartridge” so no sand ever added to that either. We just brushed, vacuumed ans cleaned the filter this morning so we will keep the PH lower and hopefully see some results! Thank you! To be continued...

 

[duraleigh]

What do you think caused your CH to be at 425 when the refill water you use is 75 CH? The only thing that comes to mind is a newish pool can shed calcium as the plaster cures. However, as long as your pH is within normal parameters the calcium would show up in solution but not in precipitate as yours has.

Has the pH ever been over 7.8 for extended periods of time?

 

[Hisbestcatch]

What do you think caused your CH to be at 425 when the refill water you use is 75 CH? The only thing that comes to mind is a newish pool can shed calcium as the plaster cures. However, as long as your pH is within normal parameters the calcium would show up in solution but not in precipitate as yours has.

Has the pH ever been over 7.8 for extended periods of time?

Hi Duraleigh,
Our PH has never gone over 8.0 and that was in the very beginning when we were adding acid daily for the start up so even with that, it never lasted more then a few hours since we test every day. We have had water for only 5 months now.

 

[duraleigh]

Well, the only educated guess I can make is that somehow calcium has precipitated from your pool walls (pretty common) and remained in solid form in your pool, hence your CH of 425.

So is it some rampant outer space chemical that is gonna' make you grow extra appendages? No. It seems to me it can only be calcium. The solution is to just let the new plaster continue to cure and it will go away.

Keep your pH in the mid 7's and test your CH every couple of weeks and it should trend downwards as the fill water dilutes the pool water. I don't think you have a real issue but I cannot explain why it is presenting like it is.

 

[Hisbestcatch]

Well, the only educated guess I can make is that somehow calcium has precipitated from your pool walls (pretty common) and remained in solid form in your pool, hence your CH of 425.

So is it some rampant outer space chemical that is gonna' make you grow extra appendages? No. It seems to me it can only be calcium. The solution is to just let the new plaster continue to cure and it will go away.

Keep your pH in the mid 7's and test your CH every couple of weeks and it should trend downwards as the fill water dilutes the pool water. I don't think you have a real issue but I cannot explain why it is presenting like it is.

Thank you! I will keep the thread updated as we go!