Confused...plaster dust? Calcium? Something Else?

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holdup1time

holdup1time

Well-known member
Jun 15, 2019
77
Houston Texas
Was swimming with my daughter on Monday and she said, "Dad, the plaster feels so smooth...kind of slippery"

This immediately got my attention...she likes to help me inspect our plaster while swimming.

She was referring to the plaster on one of the pool walls. I went over and felt it and it was very smooth/slippery feeling.

I immediately thought of slippery algae on concrete. Got my brush out and starting brushing that spot and immediately after brushing, could see white colored dusty cloud stuff in the water.

Went around the whole pool brushing and feeling for that slick feeling on the plaster. When I got done, the pool water was noticeably cloudy.

Grabbed a gallon of 12.5% liq chl and put the whole bottle in...around 5pm.

Left the pump running and decided I should perform the OCLT.

At 9pm, FC was 12ppm. Pump was off all night and no chlorine of any kind was added...got up at 530am and turned pump on ...at 6am tested and FC was 11pm...so passed the OCLT.

Also, my CC was 0 and my water was clear.

I have been very good about brushing my water line tile but have not been brushing my plaster like I should've...it's been many months.

Just curious if anyone has any idea why the plaster felt so smooth and what that was that I brushed off?

My plaster is traditional white plaster with the blue flakes mixed in.

Could it have been calcium? Baking soda i put in for raising TA? Dare I say algae?

I've always kept my FC in the target range on the FC/CYA chart.

Two days after this excursion samples are below: (Later in the day after passing the OCLT my samples were very similar to these...not much change)
FC: 10
CC: 0
pH: 7.6
TA: 60
CYA: 60
CH:325

I have to add 10 lbs of Baking Soda probably every month due to how much MA I have to add because my pH is always going high very fast...but made sure it was just the regular plain baking soda.

Oh, I did start the pool season off using Trichlor tabs...my CYA was 30...now it's between 50 and 60...so rounded up to 60. Going to try a hybrid approach using liq chl and pucks...of course monitoring my CYA and adjusting accordingly.

Any ideas/thoughts on what I brushed off would be appreciated.

At work and will be away for a few hours but will check back later...thanks!
 
I would focus on the roller coaster of acid and baking soda. You need to get off that. Look for why your pH is rising. Water features, etc.
What pH do you drop to when you add acid? How low does your TA get?
 
How often do you brush your pool?

Algae grows on pool walls. Chlorine does what it is supposed to do and kill algae. The dead algae may stay on the wall until you brush it. The CCs are long gone.

Most folks do not brush their pool surfaces enough.
 
mknauss said:
I would focus on the roller coaster of acid and baking soda. You need to get off that. Look for why your pH is rising. Water features, etc.
What pH do you drop to when you add acid? How low does your TA get?
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Hello MK...I do not know why my ph is always rising so fast....If I'm trying to keep it under 8ph all the time, I'd have to add acid every 3 to 4 days. I've been adding baking soda to raise my TA back up every time it hits 50 to 60. I have fountains and bubblers but never run them due to learning here that aeration of the water will increase pH. My pH will drop to about 7.2 when my TA is 60 like it is now. But if my TA is 100, it will barely make it to around 7.5-7.6. I wish I knew why my Ph increases so much so fast...it's been that way since my pool was built/opened last June. I've heard some people say that it's a natural thing that happens with new plaster...I do not know if there is any fact behind that or not. The only thing I can think of is that my backyard is open and gets a very nice wind....I've been wondering if the high winds ripping across the water's surface is the cause of the increasing pH.
I don't know what else to do though...my pH is going higher, I have to add acid to drop it...and adding M.A. lowers my TA....then eventually, at TA of 50, I have to add baking soda to raise my TA...unitl I found a real reason on why my pH increases so much, what else can I do?
 
ajw22 said:
How often do you brush your pool?

Algae grows on pool walls. Chlorine does what it is supposed to do and kill algae. The dead algae may stay on the wall until you brush it. The CCs are long gone.

Most folks do not brush their pool surfaces enough.
Click to expand...
Hi ajw22

Yep, as I admitted in my post, I've really been slacking on my plaster brushing...would the dead algae be white in color as I brush my plaster? There was no color of yellow or green anywhere on my plaster or in the water after brushing. Water was just whitish cloudy....Luckily, I've not had algae in my pool yet so not sure what color the water would be...I've read/heard yellow to greenish tint.
 
Will the pH stay at 7.8 or 8 once your TA is below 80? I know some areas of Houston have high TA fill water, but mostly you should be using rain as fill water.
 
TA of 50 is ok. Don't add baking soda when you get a TA of 50. Leave it as is.

Once you get to TA 50-60 just lower your pH from 8 to 7.6-7.8. Don't drop it to 7.2.
 
holdup1time said:
I've read/heard yellow to greenish tint.
Click to expand...

If it is live algae. Algae can be in clear water. not really visible on surfaces. You always have some algae trying to take hold in pools and chlorine does its job and kills it before it gets out of control.
 
mknauss said:
Will the pH stay at 7.8 or 8 once your TA is below 80? I know some areas of Houston have high TA fill water, but mostly you should be using rain as fill water.
Click to expand...
Its hard to say...I use the Taylor 2006 test kit...the device I test the pH has the highest reading at 8.2 i think...but 8 to 8.2 color is so close it's hard to tell which one it is ....to me it looks like its the highest reading on the scale...that's if I don't add acid. I actually tested my fill water last month ....CH was 175, pH was 7.6, and TA was 70...and you're right, I've only had to use the fill line a few times...mostly get help from the rain
 

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holdup1time said:
Ok if I leave my TA at 50, and add acid to lower from 8 to 7.6, will my TA keep dropping? How low can it go?
Click to expand...

TA does not drop when you make small reductions in pH, like 8 to 7.8.

If your TA drops to 40 then you should bump it up to 60. But give it a try. Many pools are happy running TA 50-60 and pH of 7.6-8.

What is the pH and TA of your fill water?
 
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I get that sometimes. I think it's just accumulated dust from slacking off I can turn a crystalline pool murky in a few minutes. But it clears up. When I know I need to have it looking really good, like for guests, I brush every day for three or four days before. Then it stays clear no matter who is rubbing on the walls.
 
You have an autofill?

With fill water of TA 70 and Houston level evaporation I think there is little risk of your TA going below 50 unless you are too aggressive with the MA. Your fill water will be driving your TA up from 50-60.
 
Richard320 said:
I get that sometimes. I think it's just accumulated dust from slacking off I can turn a crystalline pool murky in a few minutes. But it clears up. When I know I need to have it looking really good, like for guests, I brush every day for three or four days before. Then it stays clear no matter who is rubbing on the walls.
Click to expand...
Thanks for the reply Richard....definitely going to do better with brushing...can't make any excuses...just got lazy with it!
 
ajw22 said:
You have an autofill?

With fill water of TA 70 and Houston level evaporation I think there is little risk of your TA going below 50 unless you are too aggressive with the MA. Your fill water will be driving your TA up from 50-60.
Click to expand...
I do not have autofill...just a manual water valve to open an water fills through a pvc pipe into one of my skimmers. I am the level control mechanism :)
 
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