Winterize in Southern California

[chem geek]

Your pH is too high and needs to be lowered. Part of the reason for the high pH is your high TA. A saltwater chlorine generator pool tends to rise in pH so keeping the TA lower at around 70 ppm helps as does having the Cyanuric Acid (CYA) at around 80 ppm and the FC at 4 ppm (minimum) helps to reduce the generator on-time. You can also use 50 ppm Borates, but can do that for next season if you want. You didn't tell us your CYA level nor your Calcium Hardness (CH). You should get a Taylor K-2006 kit via this Amazon link for the K2006A or this one for the K2006C which will give a small amount to this forum (the price on Amazon for this test kit is usually excellent, however).

By the way, if you are adding 1 gallon per week to your 24,000 gallon pool, then your TA should be dropping by about 21 ppm per week. Since it is still fairly high, are you adding anything to keep the TA higher and if so you should stop doing that and let the TA drop to around 70 ppm.

[kirkinsd]

On the 16th I added 1 gallon of muriatic acid. Today I tested & got these results:
FC=2.8
PH=7.8
Alk=90
CYA=120
CH=620

So I added another 1/2 gallon of muriatic acid. My PH is down to 7.2 but do I need to deal with the hardness? My fill water only 150. I have a feeling it's time to drain half the pool. Ouch.

Do I need to deal with the CH & CYA?

Thanks,
Kirk

[chem geek]

You will need to do a partial drain/refill to lower the CYA level at some point but as to whether you do that now or wait until spring is up to you. If you don't do it now, then you should keep your FC level higher to prevent algae growth. The usual rule for an SWCG pool is an FC that is around 5% of the CYA level so around 6 ppm as your target. With the water getting cooler, algae will grow slower anyway, but then chlorine will kill the algae more slowly as well.

As for the CH, the calcite saturation index with your numbers before you added the acid is around +0.3 which isn't too bad for causing scaling in a manually-dosed plaster pool, but it would likely have you get a lot of scaling in your SWCG cell. However, as the water gets colder, your SWCG will probably shut off and you'll be manually dosing the pool over the winter. So whether you do the partial drain/refill now or later is up to you. If it were my pool, I'd probably do it now just to avoid any scaling issues if I got lax over the winter and the pH went up too much, but that's just me.

[kirkinsd]

Chem Geek -
You've confirmed what I thought I would need to do.

I'm unsure of the best way to drain. Should I drain as I add fill water or do I actually drain to just above the basket and then add fill water?

Thanks

[aylad]

Draining to just above the basket and then adding fill water will work, but it will be very slow. Assuming you're wanting to drain 1/2 the water, I would say 3 or so drains of 1/4 would work. Otherwise, I've seen reference to the "sheet method" (can't remember if it's CarlD or Poconos that has used it) where you put a sheet of plastic on top of the water and drain from under the sheet as you fill on the top--it's supposed to keep the chems in the top and bottoms from mixing.

Here's an old thread that talks about the sheet method--see ChemGeek's reply toward the bottom of the thread..http://www.poolforum.com/pf2/archive...hp/t-6121.html

[mas985]

I've done an in-place refill before without using a sheet. The key is to introduce water at one end of the pool without too much mixing (pump off) while at the same time, remove water at the other end of the pool, preferably the deep end via a siphon. I have replaced over half the water this way and the result seemed to work without too much mixing (i.e CH dropped as predicted).