Draining and replacing vinyl liner swimming pool water

[CarlD]

We try! It takes a whole bunch of us to keep it awesome! We've got chemistry geeks, pump geeks, metal (in water) geeks, plumbing geeks, solar geeks, heater geeks, construction geeks, etc!

[ross_badger]

Information for my pool with cloudy water:

In-ground 18'x36' vinyl lined pool roughly 9 years old
29,000 gallons
Pump size = 1HP
Filter = Hayward Sand S240 (replaced sand end of last year)

Actual readings using the Walmart HTH 6-way test strip:

Chlorine = < 0.5 ppm (after dumping roughly 40 gallons of chlorine in 2 weeks)
pH = 7.0
Total Alkalinity = 130 ppm
Calcium Hardness = < 200 ppm (water started out blue from kit)
CYA = 80 ppm

The current condition of the water is cloudy enough to not see the 4' shallow bottom of the pool. I have been oxygenating the pool with homemade return PVC pipe sprinklers to raise the pH without raising the Alkalinity, as well as using borax. The pH is going up VERY slowly. I am also filling an in-line chlorinator with 3" chlorine tabs to keep a steady stream of chlorine into the pool.

So the question is.......should I drain and replace SOME of ALL of the pool water? Or do you think that I can get this under control using chemicals?

Thanks in advance for your great help!!

Ross

[PoolDoc]

You probably should do the chlorine demand bucket test, to see how much further you have to go: http://pool9.net/bucket-demand/ =>

[Watermom]

Ben has already suggested you do a bucket test. I just have a comment to add regardless of what the bucket test shows.

If it were my pool and I had a CYA of 80, I wouldn't be using pucks at all, ever. I'd use bleach instead. Pucks will continue to add CYA and yours is plenty high enough already! Besides to clear a pool up, you can't add a large enough dose of chlorine with trichlor pucks.

[CarlD]

You should be able to solve your problem by adding 7 gallons of 8.25% bleach at a time, and checking your chlorine level 3x / day. Your goal should be a chlorine level of 20ppm and each gallon of 8.25% should add about 2.84ppm of chlorine.

If you use 12% liquid chlorine, it will add about 4.1ppm per gallon and you'll need 5 of them to shock your pool (that's one full 5 gallon carboy).

40 gallons sounds like a lot, but if you didn't add it in large enough increments, your algae would just keep coming back. Since MY liner is old and faded, I'm willing to get my chlorine levels quite a bit higher to slam that algae to death.

[ross_badger]

Thanks everyone! I need to get some additional borax and try out the bucket test tomorrow. I'll post what I found out.

Ross

[ross_badger]

Well I didn't do the bucket test, but I did drain about 1/8 of the water out of the pool and replaced it....and then kept at the chlorine morning and evening, and now it is finally clear. Either at the end of this season, or at the start of the next I will have the liner replaced.....along with the water! That will help things, I'm sure!

Thanks for everyone's help, and keep up the great work on this forum!

Ross