"Sand" stain not coming up even with stainless steel brush and Yellow Mustard shock levels.

[Mike Hawk]

Calcified dirt or algae?
I haven't run a puck or citric acid on it yet. I'm a wuss and the water has been 69 degrees lately or I'd dive in and get to rubbing.

From what I've read even stubborn algae should brush off right? Water is crystal clear since the chlorine has been thru the roof lately, so at least that's a positive

May 31st
FC 1
pH 8.4+
TA 420 (WTF?)
CH 450
CYA 40
Salt 3400
Borate Didn't titrate test, probably 30-40?
Temp 71f

After that round I dosed CYA to get me to a target of 75. And dumped 2 gallons of MA to get my PH down to 7.0 and started running my tanning ledge bubbler to aerate to combat the TA. All I had was a couple gallons of bleach so I dumped them in to start.

June 1st
FC 17
pH 8.4
TA 230
CH didn't test
CYA didn't test
Salt didn't test
Borate didn't test
Temp 69f

June 1st after testing I then dosed chlorine to get to target FC mustard levels of 46.
June 2nd I was down to 43 FC over night so I got it back up to 46 in the morning.
June 3rd FC level of 27

Got a pool party coming up this weekend on June 6th so I'm just gonna let FC drift down. I've been brushing every day.

It might be mental but I think the stain has lessened. I should have taken better before pics. Guess I'll just have to wait and see and try out the acid/puck rub from here. Really baffled that a stainless steel brush is doing nothing to it. This is my first time in 7 years of pool ownership I've had a stain like this.

 

[zea3]

Drop your pH down to 7.0 once your FC is in its normal range and see if that helps.

 

[Mike Hawk]

Will do. Whatcha thinking lower pH will be combating/accomplishing? (-edit, ahhh... "High PH can lead to calcium scaling")

FWIW I've always been fighting high PH and TA. It would probably help if I start check my chemicals weekly/biweekly instead of monthly though

 

[zea3]

You have borderline high CH. CH will start to form scale when the pH is high. By dropping pH to 7.0 you can dissolve any CH that has dropped out of solution and started to form scale.

 

[Mike Hawk]

Interesting, according to the Pool Math, a CH of 450 is right in the middle of ideal for my plaster/swcg setup

What Are My Ideal Pool Levels?

Use our tool to find ideal chemical levels for any swimming pool. Check TFP recommended levels on pH, free chlorine, cyanuric acid, and more.

www.troublefreepool.com

 

[zea3]

I think the higher values on the scale are there, because you can manage a pool with CH levels that high, IF you follow the CSI index to keep the total CSI in range. We treat the CSI index as an advanced pool care technique that most members don't need to worry about. It can be important to pool owners with high CH levels. I'll ask someone with more hard water experience to comment.
@mknauss

 

[mknauss]

Do you use PoolMath?
CSI is calculated by Poolmath. You must turn on CSI in the Settings. Share the Poolmath logs and that lets us see your information.

With very high TA and pH, almost any CH can cause scale.

Right now, if you could scrape some of this off (it will be rough and raised above the pool lining if scale) and put a drop of acid on it that will tell you if it is scale or not.

 

[Mike Hawk]

I'm old school and still use the web based PoolMath plus a spreadsheet for logging.

Guess I might come into the 21st century and start using the app

 

[mknauss]

The web based Poolmath shows your CSI. Enter your current test data and look at the CSI. If above 0, you need to get it to between -0.3 and 0. If you find what you showed above is scale, then lower the CSI to -0.6 to get it to release. It will take weeks for it to occur. Other option is to get a pumice stone and scrub most of it off.

 

[Mike Hawk]

Probably a CSI ~ -0.23 or so.

I'll wait for the FC to drift down to 5ish so I can get accurate readings of pH and then start working on the MA/Aerate dance to get my TA in shape. Definitely gonna be monitoring daily/every other day or so for a bit till this has settled down.

I'd like to go the least invasive route as this is fresh QuartzScape. I was really hesitant to even use the stainless brush. Gonna try the Vitamin C tab rub trick here in a bit too.

Thanks for all the replies.

 

[Mike Hawk]

I went all rub a dub with a chlorine puck and vitamin C. No help.

It's rougher like sand paper in certain areas so I'm assuming that's the calcium precipitating out of the water and latching onto the floor/walls?

For what it's worth the stains do seem to be less now that I'm monitoring my levels now.

Off to run another full test of chemicals.