Since getting the house, I have had a large stain in the bottom of my gunite pool. It is large and kind of cloud shaped and dark brown. The stain has not changed size or color over the years except where I have attempted to treat said stain. Previous owners did not do a good job of maintaining the pool and seemed to never manage the PH levels. I found old chemicals in the shed when we moved in including algeacide and PHOSfree like they used them frequently.
I did pool school as soon as we got the house, and I follow it closely. The pictures you see are from my pool as it is coming down from a SLAM. I live in Texas and the power outage browk some plumbing (and my heater) so the pool was down for about a month. When I took the cover off, it was a mess with leaves and algae. I have cleared all of that up but the stains still persist. I am hopeful the community can help me solve this one as it is a head scratcher.
Pool details:
15K pool and hot tub (with Pentair heater)
Water source is city water
SWG Normal operations is 3400
Normal operating levels:
FC: 2.5 to 3.5
CC: 0
CYA: 50
PH: rises daily in normal operations. Starts the week at 7.4 and by the end of the week it is close to an 8 depending on weather and I knock it back down with acid
Current:
Salt: 2100 (not adding salt until I figure out the stain stuff)
FC: 11 (coming down as the SLAM is over)
CC: 0
CYA: 20 before I started slam (plan to add more once stain stuff is over)
PH: Haven't measured since starting the SLAM, was 7.2 before beginning (added acid before starting SLAM)
Ok so what about this stain? Here is what I have tried:
First time I SLAMMED the pool (slight streaks showed up in the stain like it was doing something, but could not expand/grow it)
Asorbic acid tab rubbed on stain: no change
Asorbic acid tab crushed and applied to stain: slight color lightening but clearly did not remove stain
Chlorine tab rubbed on stain: no change
Chlorine tab left sit on stain for 12-14 hours: obvious reduction in stain (round circle of clean)
crushed chlorine tab left sit on stain for 24 hours: Stain reduction
Wire brush: no change
Wire brush with 30PPM of FC: no change
Acid applied via submersable applicator with a cup of acid on it: works if left on spot for 20+ minutes less than that no change
calcium hypochlorite powder in a sock over night on stain: no change
Pouring calcium hypochlorite powder over the stained area: disolves before reaching bottom, no change in stain
You can see in the photos where my testing has improved the stain, but now it almost looks worse than if I wouldn't have done anything. You can see the circles where I have had sucess with the tabs and the acid in a dispenser. You can see the streaks where the initial SLAM and application of crushed chlorine tabs worked. Also, I have done this testing over last season and even after the rough start to this season, the stain removals have held. So whatever it is, is not growing or changing.
Anyone have any ideas of what to try next? Here are the things I am thinking of trying:
Jack's Magic stain remover (the Blue Stuff) (Perhaps the stain is manganese?)
Acid wash without draining (never done this before)
Crazy chlorine levels (Highest I have ever gone is in the 30's, so higher than that)
Any help would be super appreciated as this is frustrating me to no end. Thanks.
I did pool school as soon as we got the house, and I follow it closely. The pictures you see are from my pool as it is coming down from a SLAM. I live in Texas and the power outage browk some plumbing (and my heater) so the pool was down for about a month. When I took the cover off, it was a mess with leaves and algae. I have cleared all of that up but the stains still persist. I am hopeful the community can help me solve this one as it is a head scratcher.
Pool details:
15K pool and hot tub (with Pentair heater)
Water source is city water
SWG Normal operations is 3400
Normal operating levels:
FC: 2.5 to 3.5
CC: 0
CYA: 50
PH: rises daily in normal operations. Starts the week at 7.4 and by the end of the week it is close to an 8 depending on weather and I knock it back down with acid
Current:
Salt: 2100 (not adding salt until I figure out the stain stuff)
FC: 11 (coming down as the SLAM is over)
CC: 0
CYA: 20 before I started slam (plan to add more once stain stuff is over)
PH: Haven't measured since starting the SLAM, was 7.2 before beginning (added acid before starting SLAM)
Ok so what about this stain? Here is what I have tried:
First time I SLAMMED the pool (slight streaks showed up in the stain like it was doing something, but could not expand/grow it)
Asorbic acid tab rubbed on stain: no change
Asorbic acid tab crushed and applied to stain: slight color lightening but clearly did not remove stain
Chlorine tab rubbed on stain: no change
Chlorine tab left sit on stain for 12-14 hours: obvious reduction in stain (round circle of clean)
crushed chlorine tab left sit on stain for 24 hours: Stain reduction
Wire brush: no change
Wire brush with 30PPM of FC: no change
Acid applied via submersable applicator with a cup of acid on it: works if left on spot for 20+ minutes less than that no change
calcium hypochlorite powder in a sock over night on stain: no change
Pouring calcium hypochlorite powder over the stained area: disolves before reaching bottom, no change in stain
You can see in the photos where my testing has improved the stain, but now it almost looks worse than if I wouldn't have done anything. You can see the circles where I have had sucess with the tabs and the acid in a dispenser. You can see the streaks where the initial SLAM and application of crushed chlorine tabs worked. Also, I have done this testing over last season and even after the rough start to this season, the stain removals have held. So whatever it is, is not growing or changing.
Anyone have any ideas of what to try next? Here are the things I am thinking of trying:
Jack's Magic stain remover (the Blue Stuff) (Perhaps the stain is manganese?)
Acid wash without draining (never done this before)
Crazy chlorine levels (Highest I have ever gone is in the 30's, so higher than that)
Any help would be super appreciated as this is frustrating me to no end. Thanks.
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