Yellowing only in spa

May 7, 2010
242
Dallas, TX
I have a spa that overflows into the pool over a rock ledge My chemical levels are good, water in the pool looks amazing, but I keep getting a yellowing on the half circle that backs to the pool directly under the ledge. This yellowing is nowhere else in the pool. Could this be algae form inside the overflow ledge. There are lots of nooks and crannies in that ledge that I have green algae in the cracks. I scrape these the best I can but it bneer gets it all, and I can't scrape inside the cracks. Pool store guy suggested pouring shock directly into the spa after brushing the ledge and letting the water flow over, possible even turning on the blower to get even more movement. Any help would be great.
 
Good morning :wave: You do know telling us chemical levels are good does not mean much unless you post test results :lol:

Anyhow, if it is organic, you can try putting a 50/50 dilution of bleach and water in a spray bottle and spraying the affected area when the overflow is off. If it not organic, it could be calcium scalling or have you had the water tested for metals?
 
>> lots of nooks and crannies in that ledge that I have green algae in the cracks.

for this situation I use a simple pressurized 1-2 gallon plastic spray container, available at home depot and lowes and dilute a mix of 50/50 bleach/water.... pump the handle a few times and spray with the nozzle directly to areas under ledge. no need to rinse but release pressure inside the container and I usually pour remaining contents into pool and rinse the pressure container and wand.
 
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This wouldn't be my first guess, but it is probably an easy test to perform and would rule out one possibility. I would try holding a vitamin C tablet against one of the stained areas for 30 seconds and see if anything happens. If the stain disappears in that area then those are iron stains and can be removed with vitamin C tablets in a sock.
 

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Ok:

FC: 6 (accidentally put in extra bleach)
CC: 0
PH: 7.5
TA: 60
CA: 250
CYA: 30

Spa FC WAS 6 as well. I test this after I opened the main return valve to the spa a little. Usually it is shut off, and the only water flowing to the spa is through a bottom valve between the drains. Opening it some pushes water through the jets I think. Tomorrow I will pick up some vitamin C (thought I had some) and bleach the rock area.
 
Your numbers look great. I would increase CYA a little, but there is no rush on that. CYA at 30 is fine, but it tends to drift down through the season. By raising CYA to 50 now you will be good for the entire season.
 
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