High CYA - Draining and Refilling at same time? Or Best way?

duraleigh

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Apr 1, 2007
32,853
Sebring, Florida
Re: iron stains........I would be cautious trying to do too many things at once.

Exchanging pool water is a careful job in and of itself and I see no real economic reason to do the AA treatment at the same time.

If it was my pool, I would exchange the water and get the pool rebalanced, tested and set up to swim. Then, I would address the AA treatment. The Pool Store actually gave good advice about AA treatment in these summer conditions. You have to drop your chlorine quite low and you run the risk of and algae bloom.........really complicating things. I would wait 'til the exchange is complete.
 

duraleigh

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53healy100,

Please start your own new thread if you have more questions. It is VERY confusing to have two questioners in the same thread.
 

Ejosh87

Well-known member
May 11, 2019
51
Florida
My pool water is 80-84. Not sure about the temp of fill water. Pool water does have CH of 575 or so and the fill water is 150.

Due to the high calcium do you think I should still fill from shallow end and pull drain water from deep end? Or should I do opposite since fill water will be colder than pool water? Not sure how much CH effects water density.
 

mknauss

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May 3, 2014
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Laughlin, NV
Unless your fill water temperature is much cooler than your pool, then I would pump from the deep end and add water to the shallow using the bucket method if you do not have a skimmer in the shallow end.

CH is a dissolved solid and adds weight to the water. Salinity also adds weight.
 
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Ejosh87

Well-known member
May 11, 2019
51
Florida
Thanks, I have started the process at 8 PM today. I have a 14K gallon pool and wanted to replace 75% (10,500 gallons) to fix CH & CYA. I calculated my fill/drain rates at approximately 5 GPM (slightly less), which would be 35 hours at exactly 5 GPM. I'm assuming since I am draining and filling at the same time I should run it longer (say 40 hours instead of 35 hours to make up for any inefficiency?) Aside from that since it wasn't exactly 5 GPM, I wonder if I should add 5 more hours, to make it 45 hours total. Do you think that makes sense or is that excessive?

My thinking is it's better to overdrain than underdrain but I also still don't want to go crazy.
 

Ejosh87

Well-known member
May 11, 2019
51
Florida
The draining/refilling finished at 11:30 AM (so went for 40 hours). I tested the levels around 12:00 PM (only 30 minutes after, so assuming it probably isn't all mixed yet). I turned the pump back on so should be mixing well now and will retest shortly:

Current levels:

FC: 13
CC: 0
TA: 110
CYA: 50
CH: 325
PH: 7.7 (hardest for me to tell since colorblind and meter is slightly different than TF100 results, is it better to err on side of being low or high?)

Won't add any chlorine until the FC 13 drops to 6 I'm thinking.

Any suggestions or just let everything be and retest in couple hours?
 

mknauss

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May 3, 2014
22,404
Laughlin, NV
Wait several hours and brush the pool or swim to fully mix the water. Then retest.

I would err pH on the low side. Much worse to have too low of pH versus too high a pH.
 

Ejosh87

Well-known member
May 11, 2019
51
Florida
Wait several hours and brush the pool or swim to fully mix the water. Then retest.

I would err pH on the low side. Much worse to have too low of pH versus too high a pH.
Would turning the spa blowers on be a good idea to help mix the water as well? Just wasn't sure if ok to leave on like that since so old.
 

Ejosh87

Well-known member
May 11, 2019
51
Florida
Ok did another test (5 hours since stopped drain/fill) and showing:

FC: 12
PH: 7.8
TA: 100
CH: 300
CYA: 50 (hard to tell exactly but 50-60)

So assuming at this point I'll just let FC come down to 4-8 range and then start with Liquid Chlorine daily to keep it in that range.

Thanks so much for everyone's help.
 
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Longboat58

Member
Jul 6, 2019
6
Austin, TX
Ok did another test (5 hours since stopped drain/fill) and showing:

FC: 12
PH: 7.8
TA: 100
CH: 300
CYA: 50 (hard to tell exactly but 50-60)

So assuming at this point I'll just let FC come down to 4-8 range and then start with Liquid Chlorine daily to keep it in that range.

Thanks so much for everyone's help.
Hi Ejosh87,
Where did you end up placing the pump?
Thanks