Our pool is green and pool store says to replace sand

Jun 9, 2015
58
Greenville south carolina
Pool Size
21000
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
CircuPool Edge-40
We had a lot of rain last week and our pool turned green. So two days later (Saturday) I added 5lbs of shock. It didn’t change color but I also didn’t do a lot of brushing that day. Monday I took a sample to the pool store. The test results were:
FC: 0.08
TC: 0.13
CC: 0.05
Ph: 7.5
Hardness: 363
Alkalinity: 46
Cya: 38
Copper 0.2
Iron 0.2
Phosphate: 0
Total dissolved solids: 500

they recommended 20lbs alkalinity
3lbs shock and 8oz algaezone

I backwashed the pool and then put all those in the same day. The pool water didn’t change color. But the filter is continuously running. The next day is still green. So I call them back and they said if the color isn’t changing them I just need to replace the sand. I decide to do a deep clean first instead. So we did that. Backwashed and rinsed again. Set it to filter. I vacuumed the pool and decided to add a gallon bleach.

today it’s still green and all I have are these Clorox pool testing strips. It says

total hardness: 800
Chlorine: 5
Free chlorine : 3
Ph: 6.8
Alkalinity: 120
Stabilizer: 100

these results confuse me and I don’t know what to do now. I ordered a tftestkit yesterday.
 
Welcome to the forum!
I ordered a tftestkit yesterday.
Great! While you are waiting on your test kit, add 5 ppm FC worth of liquid chlorine / plain bleach to your pool each evening with the pump running. This will replenish the FC lost each day to the sun and also inhibit any algae in the water from growing further.
I suggest you read ABC's of Pool Water Chemistry.
 
Do you think I should replace the sand?
Sand rarely needs to be replaced. If you have pumped Floc through it or use clarifier on a consistent basis, then the sand could be compromised.
We recommend a deep clean of the sand once a year. See Deep Cleaning a Sand Filter
 
Clairifer is the stuff you slowly feed through the return? Then yes I believe we used that this year on advice from the pool store.
Clarifier is not as destructive as floc. And I see you said you deep cleaned the sand already so if the sand was not clumped up or sticky, you should be good. And as Donldson mentioned - a filter does nothing to kill algae. Chlorine does that.
 
Okay got the tf100test today. I’m really not sure how to read this stuff.

this is what I got for results

7drops x0.5=3.5ppm chlorine
CH 22drops x25=550
Alkalinity: I put up to 100 drops and it just stayed pink
Cya: 40

Can someone explain to me like a kindergartner what I need please?
 

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Alkalinity: I put up to 100 drops and it just stayed pink
If the sample turned pink when the R0008 was added, your TA is zero or below. The pH will be 4.5 or lower. You have vinegar as pool water. This needs to be resolved NOW. It is destroying your liner.
Get baking soda. At least 15-20 lbs. Start adding enough baking soda to raise your TA by 60 ppm. Let each batch circulate for 30 minutes and test TA again. Once you test a TA above 50 ppm, test your pH. Adjust with borax if necessary.
 
You need to address the 0 TA issue.
How did you get those numbers? Did you attempt to test pH?
 
No way the pH was 8.2 if your TA sample was pink after adding R0008.

Time to do the tests again. Something is not right.
 

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