Drain the Pool

Problems relating to pH and total alkalinity.
Increase ph, increase TA. Reduce pH, reduce TA.
pH chemistry advice and techniques for the pool.
Pool Newbie
Pool Newbie
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Joined: Mon 14 Jun, 2010 10:43
Location: Texas

Drain the Pool

Postby gmebane » Mon 14 Jun, 2010 10:56

Just wanted to get some advise on draining the pool. Our service tech has recommended that we drain our pool as the acidity of the water has gone off the charts. It has been about 10 years since the pool was drained. I have noticed some green algae build up just below the water line around the pool, and the techs answer was that the condition of the water is not allowing the chlorine to eliminate the algae. My question is this: Under what conditions should it be necessary to drain the pool water?

Swimming Pool Pro
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Joined: Sat 05 Dec, 2009 17:25
My Pool: Geometric 16K gal shotcrete w/exposed aggregate; Pentair EasyTouch w/wireless, 2 Intellibrites, VS-3050 pump, C&C 200 Filter, IC-40 SWG; Heliocol solar. Rocky's reel
Location: Space Coast, Florida

Drain the Pool

Postby lbridges » Mon 14 Jun, 2010 14:49

Up front: It isn't a question of water's age.

My guess is you have very high levels of Cyanuric Acid (CYA), caused by the use of TriChlor pucks, which in turn requires higher and higher levels of chlorine to get rid of algae.

This is NOT the same as high acid levels as in pH such as you would get from too much muratic acid.

Bu that's just a guess, you would need to post test result numbers to know for sure.

In some places (notably CA and AZ) there are companies that will run a reverse osmosis system to lower these chemical levels - at a price generally exceeding water costs - but perhaps practical given water rationing and/or disposal of a pool full of water.
Swimming Pool Superstar
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My Pool: 16 x 32 gunite21000 gal., Diamond Brite Blue, Swimquip XL pump, DE36
Location: Texas

Drain the Pool

Postby czechmate » Mon 14 Jun, 2010 19:28

Assuming it is too high CYA, I would drain at least to the level keeping 3 -3 1/2 ft on the bottom.
If you pool is in the sand, rock or a high ground you can safely go to all the way to the bottom while washing the algae with a pressure washer on low pressure.( If you in the Texas gumbo soil, wait for a dry spell to do it and go all the way down).
That way all that junk goes straight to the drain. Start refilling immediately with 2 hoses!
After 4-4 1/2 ft of new fill you past the danger of floating up the pool.
You can calculate the level rise and switch to 1 hose overnight. As log as you have even small stream adding, you will avoid dirt ring on the plaster.
First chemical you want to add is probably the Pool stain remover (sequestrant).
Chlorine after you have the PH corrected.
I can recommend 55 lb bag of boric acid. You will love the water change.

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