Trichlor chlorination rates

[Gig103]

I know that "Tabs" is a four letter word around here and I'm coming around to the TFP method after getting my kit, cleaning up algae, and seeing my pool look better now than at all last season!

But I'm curious about why when using bleach (and a CYA of 100) I can measure a (from what I read on here, normal) 3-4ppm burn off daily, but when I was using tabs they were keeping me steady? Is my math below roughly the reason?

Tabs: 3 tabs/wk = 48oz @ 99% = 47.5oz
Chlorine: 48oz/day = 336oz/wk @ 12.5% = 42oz

 

[dfahrion]

You have the right idea, but you are trying to compare volume to weight (isn't our measurement system fun?). Rather than reinvent the wheel figuring out the math yourself use the PoolMath tab and "Effects of adding chemicals". Set your pool volume to 12,000 and you get:
336 oz 12.5% bleach = 27 FC, 45 Salt
48 oz trichlor = 27 FC, 17 CYA, -1.47 pH, 22 Salt.
So you are still adding 27 FC/wk, but should have to play with pH a lot less and 17 CYA/wk would add up fast.

 

[Gig103]

Thanks for that "effects" section I didn't think about it. The CYA does add up fast, I can attest to that.

 

[jblizzle]

With a CYA of 100ppm, needing to add 3-4ppm is a little on the high side even with our sun. I would have expected 2-3ppm as more normal.

What FC level are you maintaining? What does the water look like?

 

[Gig103]

Every night I test after sundown and add enough to the get back up to 12ppm. The water is crystal clear for the first time in over a year. I have been adding the amount of chlorine the pool calculator recommends at bedtime. Tonight I will add it an hour earlier so I can do a test and make sure I'm adding enough. I might as well do an overnight test too but the last one had no loss.

I also have on my to-do list to check the pool light cavity this weekend for hiding algae.
Should I soak my cartridges too or is a thorough rinsing enough?

 

[jblizzle]

Any reason you do not replace half the water to get to a reasonable CYA level?

What is the FC dropping to each day? You are right though to keep the FC above 7ppm.

 

[Gig103]

Any reason you do not replace half the water to get to a reasonable CYA level?

What is the FC dropping to each day? You are right though to keep the FC above 7ppm.

Yeah I mentioned it in my algae thread. my wife adamantly refuses to "let [me] waste more water". She doesn't care that it's far more expensive to use $10 worth of bleach a week all summer instead of a single drain.

I'm finding it around 8-9 in the evenings.

 

[jblizzle]

Got any grass? Turn off the sprinklers and water with the pool water.

 

[joegus]

Two things make this system work. The proper testing equipment and the CYA to chlorine relationship. It seems you have your kit and are doing great! How positive are you with your CYA Test? Do you feel confident with the 100 reading? Then, if you read through pool school you realize that at 100 it is a very precarious place to be. If you want to keep using "pucks" and raising your CYA levels and spending more money, please feel free to do so. Or, when your pool turns green because your "pucks" continue to raise your CYA and you cannot possibly keep a FC level to maintain clear water, perhaps you will come around.
You are at that "tipping" point, my friend. I have seen and been where you are. You think, "if it's not broken, why fix it?".
You will fix it because it will make having a pool a living ****. The algae always wins.
You will think that dichlor and trichlor are your friend. They have always helped you in the past. If they don't there is always my other "friend" Algaecide.
Yes. The "pool store" people will arm you in the battle. They will also sell you tons of armaments and send in "advisors", but you will never win without spending an outrageous "war chest" of money. Why? Because they are morons only doing what they are told from politicians behind enemy lines.
Take the time and effort to learn the science of TFPC.
Once you understand the principals of how to correct and maintain your pool water and how you got there in the first place..........will you ever truly appreciate what I am saying.

Good luck. Clear water and smooth swimming!

 

[Gig103]

Two things make this system work. The proper testing equipment and the CYA to chlorine relationship. It seems you have your kit and are doing great! How positive are you with your CYA Test? Do you feel confident with the 100 reading? Then, if you read through pool school you realize that at 100 it is a very precarious place to be. If you want to keep using "pucks" and raising your CYA levels and spending more money, please feel free to do so. Or, when your pool turns green because your "pucks" continue to raise your CYA and you cannot possibly keep a FC level to maintain clear water, perhaps you will come around.
You are at that "tipping" point, my friend. I have seen and been where you are. You think, "if it's not broken, why fix it?".
You will fix it because it will make having a pool a living ****. The algae always wins.
You will think that dichlor and trichlor are your friend. They have always helped you in the past. If they don't there is always my other "friend" Algaecide.
Yes. The "pool store" people will arm you in the battle. They will also sell you tons of armaments and send in "advisors", but you will never win without spending an outrageous "war chest" of money. Why? Because they are morons only doing what they are told from politicians behind enemy lines.
Take the time and effort to learn the science of TFPC.
Once you understand the principals of how to correct and maintain your pool water and how you got there in the first place..........will you ever truly appreciate what I am saying.

Good luck. Clear water and smooth swimming!

My post was more about how I'm not used to daily maintenance and wanted to make sure my understanding was correct - that the pool will lose a few PPM daily but I never knew since the tabs were replenishing.

I wouldn't say I'm planning on going back to tabs on a regular basis, but now that I understand how they work I will probably just hold them back for when I'm on vacation. Or is it preferable to shock 3 days worth and let it float down?

Thanks for the well wishes, I am not giving up (although I will probably need more R0871 sooner rather than later at a 12ppm daily level!)

 

[bridgman]

Yeah I mentioned it in my algae thread. my wife adamantly refuses to "let [me] waste more water". She doesn't care that it's far more expensive to use $10 worth of bleach a week all summer instead of a single drain.

After you pour each gallon of bleach in, fill the bottle up with pool water and dump it somewhere. It won't make a real dent in your CYA level but it'll make you feel better

 

[Gig103]

Well I have to correct my earlier statement about getting back to 12ppm. I put in the same amount (48oz) of liquid chlorine but this time I tested the water an hour later (I think I mentioned before that I usually test & add at the end of the night), but the FC reading is only up to 10ppm. A quick check with the calculator deduces that I'm putting in the equivalent of 6% even though the bottle says 12.5%! I guess I've been ripped off, the question is how intentionally. Either way, even if it's just poor storage I won't be buying more from that pool store.

 

[jblizzle]

You sure the pool is not bigger than you think? Although certainly not double.

 

[Gig103]

Good point JB. I did get the home in a foreclosure so I can't be positive. But when we drained it two years ago with a 60gpm pump it took about the right amount of time for 12k. Maybe I'll get the tape out tomorrow and use the site calculator estimator. It is irregular shaped though.