Does lowering (or raising) Ph have any effect on organic stain removal?

Dan8899

Bronze Supporter
Nov 4, 2017
37
Apache Junction, AZ
Pool Size
15000
Surface
Plaster
Chlorine
Liquid Chlorine
Hi all,
I've been sentenced to weeks of hard labor for my negligence/ignorance - Brush till I drop Organic stain removal

For the experts who may not want to muddle through my narrative, the main question is assuming I follow instructions in PSchool stain removal maintain 60-100% shock value and brush brush brush, will lowering the Ph say to near 7.0 increase brushing effectiveness?
Does a calcium buildup on plaster start shrinking (be reabsorbed into the water) when the water CH level is lowered?

I think this is a good story and lesson for any new pool owners like me, following and then Not following the simple, quick, economical methods promoted on TFP, and the price you will pay if you let it get away from you.
Backstory- So I found, learned, and was following the TFP way since becoming first time pool owner back in 2017. The method worked too well in my case, and with test results always being within the acceptable range for over 1-1/2 years, I got comfortable and started testing less often..... I 'knew' what FC was being lost daily in summer, in winter,....so I 'knew' just how much CL to add each day. What started as faithfully testing turned into FC & PH every couple weeks then months and TA, CH, & CYA almost never because the values never moved. In my overconfident mind clear water, no algae, no problems...and quickly forgot the big picture. CH was always the same and my CYA levels that started at 50 in 2017 had actually been lower closer to the 40 line. This fact should have been a red flag since I probably read 100 posts on here and stared right at it on the Poolmath calculator 100 times that CYA and CH can only be lowered by Replacing pool water. It just never clicked in my brain. I mean even people that don't own pools that I tell about my 'problem' seem to know that every several years you need to drain/refill your pool, especially here in AZ. Tap water CH test today was 250ppm. (Water softener on to-do list.)

The reason my CH & CYA levels were staying the same/lower is blatantly obvious to me now. I have been replacing the water in my pool since 2017, but just never realized I was doing it. When I bought the house the water bill came, same next month, etc....assume that's the normal usage...who wouldn't? Bigger things to worry about than avg $30 water bill.... July 2020 my water bill showed 10,000 more gallons used than the month before. No wet spots in my AZ yard anywhere near pool, guessing due to gopher tunnels, but eventually I found it -a broken 1-1/2" return pipe about 30" deep.

Now this year I get to pay for my sins. Family crisis this past spring led to adding no CL to pool for 2 weeks which quickly turned green. I cleaned it, and within a month lost it again due to my mind being elsewhere, except this time it was several weeks until I got motivated to clean it. And this time it wouldn't brush off the floor of the pool. The fluffy green top came off but a dark brown stain remains everywhere. About 80% of the pool floor is now covered in brown stains. I don't have a pic but it looks exactly like the staining in 2 pics in the post 'plaster stain removal over winter' 9/4/2019, except much worse.

What I 'Think' I know after much research on TFP, ordering fresh reagents for TF100, and faithful testing since 8/6:
- I need to start replacing water to get CH down and intend to time fill hose g/min into bucket and use my 3/4" sump pump pumping as much as my AZ postage stamp sized yard can drain per day without exposing plaster at theses temps, following posts about water temp & fill-drain positions to maximize replacement volume.
- I know I still have a pool leak somewhere based on CH levels Dropping and CYA levels holding even with pucks in the floater - possibly partially due to several visible small cracks in the plaster floor that showed no signs of algae growth or current staining like a blue plaster island surrounded by brown stains, assuming this is due to water flow at those locations, or another ug pipe is partially separated(water bill up again past 2 mo)
- I know the staining is organic based on 1- after spreading an old 1lb 'shock' packet inherited with the house, I can clearly see white track marks where the granules rolled across pool floor completely removed the staining and, 2- a triclor puck placed on pool floor for 5 min also dramatically decrease stain darkness partially removing it
- I believe the reason the staining took hold is partly due to the CH being high causing unnoticed calcium scaling that the algae then attached to, as I can feel areas where the brush seems to slightly raise up as if going over a buildup at some spots

8/6/21 - FC 7, CC 0.25, PH >8.2 max gauge on K-1000, CH 800, CYA 45, TA 130
add MA targeting 7.2 to lower TA add CL 77oz 12.5% attempting to add 5CL to get benchmark usage
nylon brushing negligible effect - minor brown cloud immediately becoming invisible- water remains crystal clear

8/7/21 11am - FC 6.5, CC 0.25, PH 7.6, CH 775, CYA 45, TA 110
add MA targeting 7.2 add CL 64oz 12.5%

8/7/21 7pm - FC 7, CC 0.25, PH 7.2, CH 775, CYA 45, TA 100
add CL 128oz 12.5% And sprinkle that 'shock' packet, brushing has no/minimal effect
frustrated, order steel bristle pool brush, continue adding 1/2gal CL 12.5% /day to maintain until brush arrives

8/11/21 am - FC 11, CC 0, PH 7.4, CH 750, CYA 60(increase no doubt from 'shock' packet and 3 pucks thrown in floater), TA 100
steel bristle arrives but brushing has almost no effect
frustrated, continue adding CL & MA daily to maintain elevated CL & lower PH/TA while I do more research....

8/21/21 today - FC 10, CC 0, PH 7.6, CH 700, CYA 60, TA 90
ordered 2 t-stats to monitor water replacement in/out locations and aquachek salt test strips to verify salt level since now aware of CSI value parameters and >0.6 issues

Intend to maintain shock level FC (currently [email protected]) and ph 7.2 while continuing to brush brush brush until the stains are gone

Same Q's as above:
-Does Ph value have any effect on brushing stain removal effectiveness?

-Does a calcium buildup on plaster start shrinking(be reabsorbed into the water) when the water CH level is lowered?

-Maybe stupid question, but since I will be replacing all my water anyway over the next month or so, and assuming no one is going swimming any time soon, is there any downside to scattering say 10 of those 'shock' packs in all at once, brushing it around, considering how very effective 1 pack was at eating away the stains? the added CYA will be removed anyway right?

thanks for any advice
Dan
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
29,125
Northern NJ
Pool Size
35000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
First of all, pH drop tests are invalid with your FC over 10. So don't go adjusting pH during the SLAM Process. Follow the process and adjust your pH to 7.2 - 7.4 before you raise FC level then leave your pH alone while maintaining your SLAM FC level.

It is not clear from your story what type of stains you have. Or if you have a mix of organic stains and calcium scale.

The SLAM Process may deal with organic stains.

You need to treat different types of stains in different ways and do them one at a time.

Spreading shock on your pool floor may clear the stains but it may also create their own stains on the plaster surface. I would watch the pool floor and brush the shock around as soon as you see the stains lift and not let the shock sit on the plaster.
 

Dan8899

Bronze Supporter
Nov 4, 2017
37
Apache Junction, AZ
Pool Size
15000
Surface
Plaster
Chlorine
Liquid Chlorine
thanks, I forgot PH invalid at high FC. Here are some pics. When I mentioned feeling the brush rise up as if going over a raised area that only happened at a couple places. Mostly it feels flat as I brush.
 

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ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
29,125
Northern NJ
Pool Size
35000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
That is ugly.

Calcium scale feels like sandpaper. You need to feel the surfaces with your hand and see if they feel like sandpaper or smooth. The bumps could be just uneven plaster.

Those deep stains may take elevated chlorine levels for many months to clear. It took months to get that bad and may take as long to clear. Unless your "shock" treatment works.

With your CYA at 50 your SLAM FC is 20. I would run the pool at a FC level of 15-18 until the stains are gone. It is safe to swim at that FC level just regularly check your CYA. Over time you should see the stain lighten and get bleached out from the chlorine.

You will need to let your FC drop below 10 once in a while to check your pH, lower it back to 7.2, and the raise your FC to 18 using liquid chlorine.

I don't think the SLAM Process will clear those stains in any reasonable time.
 
Last edited:

Dan8899

Bronze Supporter
Nov 4, 2017
37
Apache Junction, AZ
Pool Size
15000
Surface
Plaster
Chlorine
Liquid Chlorine
Very ugly indeed. Thanks Allen. I will try the 'shock' brushing in a test area on one of the darker stained spots. Using caution to avoid further damage as you suggest. If I gain any ground I'll take a pic. This debacle is another lesson learned the hard way.
 
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