Salt, heat, bad chemistry -- yikes!

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KenShu

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Jul 3, 2011
12
Pool is 16 years old. Was replastered and converted from traditional chlorine to SWG last summer--worked great for a year. With record heat this summer, water temp is 95deg. Several days ago we had a big rainstorm, and the pool started greening up. Took water sample to pool store, added conditioner, acid, stabilizer, yellow out, SuperZappit. Backwashed filter twice.

Things looked better, then green algae returned to the water line, and now there is a very persistent yellow algae in spots on the pool walls.

Latest test results from pool store: FC=0, CC=0, ph=8.2, TA=130, CH=200, CYA=45.

I'm buying way too much chemical from my friendly pool retailer, and this yellow stuff will not scrub off.

Looking forward to your advice!

Ken
 
Ordered TFT test kit. Until it arrives, I am monitoring salt level and using OBO test kit + PoolCalculator to manage FC & pH.
Salt = 3,600
FC = 4 early morning, goes to 0 by end of day (high heat, full sun)
OFCL = < 1
ph = 7.6
Clarity = excellent
Still some persistent yellow on walls & green in grout, but waiting on test kit to determine CYA. Then will shock and start working toward specs for CYA, CC, TA, CH.

What else should I be doing? I expect the test kit today or tomorrow.
 
What else should I be doing?
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You did a good job getting the chlorine in there. I would be almost sure you will need to shock the pool (after we see the test results).

Assuming that, it will not hurt one bit to dose the pool with a couple of large jugs of Clorox each evening until your kit arrives. That quick, almost instantaneous dose of clorox will kill a lot of algae and will make your chlorine demand reduced by a lot once you begin to shock.

Post up the test results as soon as you can and we'll help get you started down a path to a sparkling pool from here on out!! :lol:
 
Got the real deal test kit, here are the results: FC=1, CC=0, pH=8.2, TA=140, CH=370, CYA=90. I still have the pesky yellow on the walls and green in the grout, water clarity is excellent.

Calculator says add bleach to up the FC, add acid to lower the pH, drop pH to 7.2 and aerate to lower TA, replace water to lower CH, replace water to lower CYA.

My plan is to treat the FC and pH today, and take it up to shock level since the algae isn't moving. I'm out of town for a few days, then will work on CH & CYA later in the week.

Is it OK to add 36oz acid, repeat 30 minutes later, then 1 gal bleach every 30 minutes until full dose is added?

Welcome your feedback--is this an OK plan? Thanks in advance.
 
Ken,

I would suggest you focus on lowering your pH down to 7.2 - 7.4 or so. Once that's done and you test the results ( you can test roughly 30-60 minutes after adding acid), you're ready for the next step.

Next, because you are headed out of town, do not shock the pool (man, I NEVER thought I would find myself saying that). Read the article entitled "How to Shock your Pool" in Pool School and you will find it is not something you can dose once and ignore. Shocking is a process over a period of days and will require your attention.

Then, when you return, consider lowering your CYA to around 50-60ppm by draining 1/3 or so of your pool water. This will make EVERYTHING in your pool more manageable.

Having lowered CYA and pH, you are now ready to start the shock process. Read how to do that in pool school.
 
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