Going through a lot of liquid chlorine

[joshf]

This is my first season using the TFP approach and liquid chlorine (last year I used tabs - I have since replaced most of the water).

I'm very happy with the water - its is sparkling and clear, and I no longer see the hints of algae that I used to get occasionally.
However, I seem to be going through a _lot_ of chlorine. This approach seems like it will be a lot more expensive than an $80 bucket of tabs that lasted me the whole season last year.

When I originally measure CYA, I thought it was at 50, so I've been following the recommendations accordingly (trying to keep between 6-8). But with all of the FC loss every day, I started to suspect my CYA was lower and I'm burning off a lot, so I retested yesterday, and it seems like it is closer to 40, so I've changed my target to 5-7.

I've attached my recent logs - you can see I've been adding more than half a gallon every day.

Is this "normal"?

Should I consider adding a couple tabs to try raising my CYA?

 

[JoyfulNoise]

A clean & clear swimming pool can use up to 4ppm FC per day (2-4 ppm is normal). In your pool, a half gallon of LC (10%) will raise FC by 3.3ppm.

How much are you paying for liquid chlorine?

 

[Catanzaro]

When exactly are you adding the bleach? Check the Julian date to make sure the bleach is not old? How many ppm are you losing daily? How hot is the weather, and how much activity in the pool?

 

[joshf]

I've been buying Home Depot HDX Liquid Chlorine. 10%, 3 gallons for 8.98. I've been paying attention to the date codes to never buy more than a month old (bought 12 gallons of 19 163 today) and store it inside out of the sun.
I usually add the bleach at night. There isn't much drop by the morning, but by evening the next night, it needs at least another half gallon.

Maybe my calculations are off in stating it would be "a lot more expensive than $80" for the season. It feels like a lot. Maybe because I was originally targeting 8ppm. If I keep it closer to 5, it may be more manageable.

 

[Catanzaro]

Your CYA should be closer to 50 ppm. What I would recommend is adding the bleach and allowing the pump to run over night for a few days, or maybe perform a SLAM for 2 days, then allow your levels to drift drift down under 10, closer to your normal levels during the evening. Then perform an overnight test.

Again, you did not mention how much loss there is in a 24 hour period. In addition, it is suggested highly you post a full set of test results. Maybe you have small amounts of algae (not visible), and/or combined chlorine that is consuming the bleach.

Tabs are usually less expensive in the short run, but long term create all sorts of problem with dropping PH and high CYA. Then the amount of time wasted is really not worth saving that $50 per season, or even $100 at most. Liquid Chlorine is highly predictable. Even though I converted to salt, I am constantly making more adjustments or shutting off the cell for a few days. Please keep us posted!