Water Change I'm afraid.

[sgraham308]

Pool came with the house we just bought and thay had only been using pucks and frog chlorinator system as their sole sources of chlorine since they installed the pool, which was 3 swim seasons ago. When they told me this, i automatically expected the CYA was going to be sky high. So I finally got a TF100 and tested my water. As expected, the CANADIAN test showed that it is significantly higher than 100. The water level in tube comes up to roughly 1/4" below the lowest graduation on the vial. The FC was around 12 with a CC of 0. The pool was never closed as is generally the case in southern alabama. Just run the pump when the temp drops and carry on. My question is this:
Should I just go ahead and drain it all and start over or would it make sense to leave about 1/3rd of it and refill. Any comments or suggestions are welcome. Thanks in advance for your input.

 

[JohnT]

Don't drain it all.

You may struggle to get the liner back in place, and if a high wind were to come up while the pool was empty you could lose it.

You can drain a foot or so at a time and refill untill you get it where you want it.

 

[jblizzle]

You can do the CYA test starting with 50/50 mix of pool and tap water and then add reagent and then view the tube a waist level with your back to the sun outside. Pour back and forth a few times and see what you get ... doubling the reading will be an approximation of your CYA level.

Likely draining a foot at a time will lower the CYA by about 25% each time (depends on water depth). So if you were at say 200ppm each 25% reduction would leave CYA as:
1 - 150
2 - 113
3 - 84
4 - 63
5 - 47

So would take 5 cycles to get into range.