My pool seems to want HUGE amounts of chlorine

[frustratedpoolmom]

No, you don't need to lower the TA before you shock.
High TA will cause the PH to drift up; when it does, you simply lower the PH down to 7.2 with muratic acid. The acid additions will also lower the TA, and eventually the TA will come into range. Now, don't try to adjust PH while shocking- because high FC levels (over 10) will make the PH reading inaccurate.

I'd suggest you lower the PH to 7.2 before you begin, and once you have completed the shock process you can focus on other things.

The cloudy water can be caused by a number of things....in your case it was probably the high CYA was rendering what little chlorine you had ineffective.

 

[ssa]

If don't know how many times you need to half drain the waters, one way to save water
is avoid fill up to 100%. Keep the water level low about 50%, add some water and drain
some water. Repeat this process until the CYA level is in check. Actually your
CYA level should be twice the expect level, because you need to add another 50%
fresh water.

Here is the reason:

Assume you have 50% water, if you fill up to 100% then drain back to 50%.
Half of the water you drain is from the water you just add. You waste 50%
of the water you just add.

If you keep the water level around 50%, add 10% water and drain 10% water. Then
from the water you drain. Your drain 1/6 of the fresh water you just add. It is 16.7%
rather than 50%.

In other words, by keeping the water level around 50%, you effectively reduce
your pool size to half. So you waste fewer water during the drain/refill process.

I have been though the same thing. Except that I estimate my CYA level
is >1000 from previous owner. I am not supprised if some one tell me that
level of CYA is enough to kill bacteria by itself.

Another idea is that, if some one can find some huge plastic bag, some thing like
10' x10' big. I can just put the plastic bag in the pool. Add water inside the
bag, and drain water out side of the bag. In that way no water will be wasted.
The bag does not need to be strong. 1ml should be good enough. It is
just used to separate the water. Some minor leak is ok too.

 

[chem geek]

Compare two 50% partial drain/refill vs. the one 50% followed by 5 10% partial drain/refill and then a final fill up. Start with a CYA of 200 ppm.

Start: 200 ppm
50% drain: 200 ppm
50% refill: 100 ppm (same CYA, but twice as much water)
50% drain: 100 ppm
50% refill: 50 ppm
used 100% of the pool water volume to dilute down to 25% of the original value

Start: 200 ppm
50% drain: 200 ppm
refill 10%: (5/6)*200 = 167 ppm
drain 10%: 167 ppm
refill 10%: (5/6)*167 = 139 ppm
drain 10%: 139 ppm
refill 10%: (5/6)*139 = 116 ppm
drain 10%: 116 ppm
refill 10%: (5/6)*116 ppm = 96 ppm
drain 10%: 96 ppm
refill 50%: (1/2)*96 ppm = 48 ppm
used 90% of the pool water volume to dilute down to 24% of the original value

I assume above that the "10%" drain and refill is 10% of the original pool volume, not 10% of the half-volume. So your method does same some water though takes more drain/refill cycles.

Richard