Significant chlorine drop in 24 hours

[RhamanShaman]

Hello all! I recently started reading these forums after having cloudy water continuously for a couple weeks. My chlorine levels tested consistently high at the LPS, so I suspected that I needed new sand in my filter. Well, the pool store said they could not replace my sand because my filter was no longer supported by the manufacturer, so they were unable to order new parts for it. They wanted to replace it with a new one, with an $800 price tag (Ouch!). So I took to the internet to find a different solution. I deep cleaned the sand as directed by the wonderful tutorial and videos I found on this site and ordered the DPD Taylor K-2006 test kit. I bought some bleach and proceeded to SLAM my pool. My water is crystal clear now! However, I have a few questions. Here’s what’s going on in my pool as of this morning.
PH: 7.8
TA: 80
CH: 90
FC: 7
CYA: 90
My FC was 12 yesterday morning and now it’s at a 7? Is that the kind of decrease I’m going to be seeing from now on since I’m no longer using my tablet chlorinator? Also, I had my water tested at leslies on Saturday and the CYA was 55. I’ve not been using tablets since Wednesday of last week. Is that just a discrepancy between the store kit and the test kit I’m using at home? I know I need to add about 50 pounds of calcium chloride to get my CH up, but the pool looks so good I didn’t want to cloud it before this weekend when my MIL will be visiting. I’ve read pool school and looked at the various chemistry stickies on here and I’m wondering if the chlorine loss is related to my CH and CYA levels. One more quick question, by using bleach now as my sanitizer will I be adding bleach almost daily throughout the season? And should I waste some water in order to reduce my CYA level, because it seems that with daily losses of chlorine of 5ppm that it would be difficult to keep my FC at the recommended level of 9 with the CYA being what it is.

- - - Updated - - -

• Test kit being used- IS the K-2006
• The size of your pool in gallons - 33000 gallons
• If your pool is an AG (above ground) or IG (in ground) IG
• If it's IG, tell us if it's vinyl, plaster/pebble, or fiberglass - Gunite
• The type filter you have (sand, DE, cartridge) - Sand filter
• If you know, tell us the make and model of your pump and filter.
• List any other equipment you have: SWG, second pump, etc. - Polaris
• Please mention if you fill the pool from a well or are currently on water restrictions - Poole filled with city water

 

[cowboycasey]

Welcome to TFP

You are all over it on many points, nice job... take all your info on the bottom and put it in your signature Trouble Free Pool

So, CYA, at 90 you should be targeting 10 and always stay above 7 Pool School - Chlorine / CYA Chart
if you can drain some water to lower CYA the less chlorine you will need..

With that said, you took your FC to 12 so it dropped very fast to about 10 then continued to drop, your FC should stabilize some, we usually see 2 to 4 PPM drop per day and your pool is on the large size, so you will be going through some bleach/chlorine... The 10% or 12.5% will work better for you as you can use less per day to hit your target.. try to find a HASA dealer for 12%

I hope this helps