Help with high FC and CYA

[bkaiser]

I just moved into a new house with pool and I'm trying to make sense of the crazy chemistry it has going on. I was able to talk to the pool cleaner that the last owner was using and he told me that the previous owner refused to partially drain and refill the pool to reduce the high CYA for whatever reason. He also said it's very common in San Antonio for the pools to have both high CYA and FC numbers since hardly anyone uses liquid chlorine. I've removed all sources of chlorine and tested it today with my K2006 kit. I'm getting FC of around 17.6 ppm and CYA that's way off the gauge. I've attached pics. These readings were after me draining to just below the skimmer and refilling back up, I couldn't figure out how to pump any more water out without the pump running out of water. That's another issue

 

[jimbethesda]

First step is to determine what your CYA level is by doing the diluted test below. Then you will know how much to drain. 17.6 is likely not that high at all.

For CYA > 90ppm, repeat the test adjusting the procedure as follows:

1. Fill the mixing bottle to the lower mark with pool water.
2. Continue filling the mixing bottle to the upper mark with tap water.
3. Shake briefly to mix.
4. Pour off half of the contents of the mixing bottle, so it is again filled to the lower mark.
5. Continue the test normally from adding R-0013, but multiply the final result by two.

If you need to dilute the pool water further then apply these ratios:[4]

Pool water	Tap or distilled water	Multiply result by
1	1	2
1	2	3
1	4	5

Note that when doing a diluted test not only do you multiply the range of the test you mult