Pool ring

Rick T

Well-known member
Apr 28, 2019
109
Houston, TX
I wasn't sure which section to post this in. I have been doing the TFP method for over a month now. My pool has never been more clear. I have a flagstone around the waterline of the pool. It has a dark ring that has been there for a long time. Today I took a 3" chlorine tab and rubbed it over the line. I let it sit for about 5 minutes then scrubbed with a pumice stone. Very little to no change. It's right on the waterline. Any ideas on how to get rid of it? Thanks.


ring 2.jpgring 1.jpg
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Looks like maybe a scum line? I get it in some areas once or twice a year, but on my FG pool I can use a Magic Eraser. Have you tried some diluted muriatic acid/water? Spray some (maybe 50/50), give it a few seconds, then rinse or brush a little. As always though, do a small test area first.
 

Rick T

Well-known member
Apr 28, 2019
109
Houston, TX
yesterday I put 50/50 muriatic and water in a spray bottle and went around the pool. Not sure why but a few places foamed up. I then let it sit for a few minutes the scrubbed with a bristle brush. Scrubbing had little effect. I then sprayed another coat and let it sit for 10 minutes then rinsed it off with pool water. The acid turned the ring from a dark gray to a medium brown color. My ph went from a 7.8 to a 7.5 with the acid used. Today I filled the spray bottle with straight 10% bleach. I sprayed again, waited a minute then scrubbed with a bristle brush attachment on my drill. Again scrubbing had little effect. I went around the pool a second time with bleach and did not rinse it off. After about 20 minutes I took the after picture. I would say about 80% of the ring came off.

ring 1.jpgring 3.jpg
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
The fizzing was probably the reaction to calcium/scale on the plaster. But the signifincant changing from the prolonged exposure to bleach was related to organic staining. So it would appear the organic material was there long enough to reeally embed into the plaster or possibly be covered by a little scale. Either way, the good thing is it can be removed. The down-side is it will take some time, elbow-grease, and consistancy to remove. Possibly maintaining a slightly higher FC level for a few days might help as well.

On a side note ... those aren't rain drops are they? We haven't seen rain in what seems like over a month. Starting to miss it. My water bill is going to stink next month.
 

Rick T

Well-known member
Apr 28, 2019
109
Houston, TX
Had a little sprinkle here in Houston yesterday. Just enough to raise the humidity yet another 10%. I plan to spray the flagstone coping again today and just leave it on there to soak in.
 

duraleigh

Admin
Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
34,437
Sebring, Florida
Yeah, you had a combination of calcium scale forming and then the algae found a place to hide inside the scale. Acid will get the scale and chlorine will get the algae after it is exposed. Nice work.
 

Rick T

Well-known member
Apr 28, 2019
109
Houston, TX
Update on the ring around my pool. The dark ring is gone. I've been trying to tackle the white ring above it. I've tried multiple applications of muriatic acid (some at almost full strength), bleach, scrub brush, and pumice stone. The white ring won't seem to go away. Any ideas? Thanks.

ring 4.jpg
 

Rick T

Well-known member
Apr 28, 2019
109
Houston, TX
I watched a youtube video on bead blasting. It said it was blasting with a glass product. I assume that is safe to be around the pool barefoot after the job was through. Is this a machine you can rent at Home Depot? I have an air compressor. Any other precautions needed to be taken?