cost/benefit shocking pool

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iam4iam said:
I wish I knew what my CYA level is. have no confidence in that test. I only know that CYA>12, since I added 4 lbs of dichlor last night.
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Why do you keep saying you wish you knew what your CYA level is? Just measure it. It is not subjective, either you can see the dot or you cant. If you can see the dot with the tube full then your CYA is too low.

Chances are your CYA is too low,
 
iam4iam said:
You are doing well, FC is higher than CC and the CC level appears to be going down rapidly.
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Actually, FC decreased way faster than CC during the hour of "the $18 test."

[quote:343yzxsi]Now that your FC level is more or less holding, shocking only at night is slightly more efficient, less chlorine is lost to sunlight.
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I thought this was what I was proposing to do in the first place (original "cost/benefit" question that started this topic)

If I remember your CYA level is around 40, so shocking during the day isn't too bad.
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I wish I knew what my CYA level is. have no confidence in that test. I only know that CYA>12, since I added 4 lbs of dichlor last night.[/quote:343yzxsi]

Also you dont have to keep wasting reagent to try the test again. Just pour it back into the mixing bottle shake it up and then drip it back into the test tube. When you have enough CYA there will be no question you cannot see the dot, even when the tube is only partially filled.
 
Good to know about the CYA test. (I've already used almost 1/2 of my reagent!) My problem is that yesterday evening there was no doubt I could see the dot with the tube full, then today, it seemed to be disappearing between 40 and 60, so I was wondering if time of day and position of the sun, etc. was the difference. I did add 4 lbs of dichlor last night, but even if that shows up already, it's only about +12 to whatever it was yesterday. (I still don't know whether I should expect to "see" the CYA from last night's dichlor in the test already.) The bottom line is, I lost 8-9 ppm of FC per 15-min for 45 min (27 down to 1), without a "conversion" into CC. (It is supposed to "convert" to CC when there's something to kill, right?) That tells me I'm low on CYA regardless of how my eyes might be tricking me on the CYA test! Am I correct in this assumption? (Unless it was ammonia, like Jason suggested!) Anyway, I know my CYA isn't over 50, so I guess I could add 20 ppm without any risk, knowing I won't be using dichlor or trichlor! Opinions?
 
I would be careful not to over do the CYA, a few hours of satisfaction now are not worth months of agony later trying to manage a pool with high CYA until it drops down due to routine water replacement. Maybe add another couple of pounds of dichlor, take a nap, and then back to adding bleach, it does sound like you are getting closer. Remember that closer does not always mean that it looks better, I to am betting on amonia at this point, once that is gone the chlorine your adding can do its primary job and kill off the other organics.
 
Hi again, OP, just hang in there. In my pool, what I suspect was the ammonia issue was so bad during the initial shocking that you could smell and gag on the sulphuric off-gassing and the FC just didn't hold long for the first while -l- I used at least 30 of my 58 gallons all within the first night and next day, in addition to the 12 lbs of shock my pool guy had added before his untimely demise by the BBB overlords ;) As soon as you get (and keep) the upper hand, your chlorine consumption will drop dramatically, I suspect.

Also, expense wise -- most of my 58 gallons were bought at ALDI for about $1.20/gal -- cheapest I've seen.

I feel for ya, but boy will you feel good -- soon -- when the shock and awe results in triumph!
 
As for the ammonia possibility, it would in theory explain 2 things:
1) my seemingly low CYA
2) my crazy FC consumption
Would FC that's used to neutralize ammonia show up as CC as if it were killing an organic? If not, it would also explain the lack of increase in CC when I shocked to 27 ppm this morning and watched the FC plummet and CC sit still. CYA remains a candidate. I'm going to go try Jason's suggestion of direct sunlight with back to the sun. I think Isaac-1 mentioned that once as well. I get 30-40 when I stand in the sun. Funny thing, when I come back onto my back porch I can see the dot again. Does the "skake" wear off? Should you repeatedly shake the bottle as you add more into the cylinder? I know I'm overcomplicating this. But unless the ammonia "consumption" of FC doesn't show up as CC, nothing except low CYA makes sense to me.
 
I'm also noticing my pH is rather low. It seems I remember reading somewhere in pool school that pH should be in "normal" range for effective shocking. I added some washing soda last night prior to the dichlor (not immediately prior, probably about an hour) to counterbalance the reduction in pH caused by the dichlor. Yesterday, pH was 7.2-7.5. Today, before adding another lb of washing soda, it was down at 6.8! (That additional 0.17 probably isn't noticeable on the color chart. Would have added a little more, but that was the end of the box. We've still got some borax, which has less affect on TA per unit increase in pH, according to pool calc. However, if I'm going to end up adding some CYA, increasing the buffer TA a little makes sense, so that the CYA has less counter effect on my pH. Most recent TA reading was 100. Am I overthinking the choice between using the borax I have or buying some more washing soda?
 

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If your PH is at 6.8, then raise it now with whatever you have on hand and don't wait around for asking questions or going to the store or picking the ideal way to do it. You never want PH below 7.0, and best to keep it at 7.2 or higher.
 
JasonLion, would that PH reading explain why he is going through so much more chlorine -- it's off-gassing so quickly (b/c low ph make ch overreact, I think?) Just curious.

I know that I (belatedly) adjusted my PH up after starting the shocking (after reading here to do so, and AFTER pool guy said not to bother...see a theme here ;)) and it seemed to start "holding onto" more chlorine almost immediately.
 
Very low PH can make chlorine far less effective, but it wouldn't cause the chlorine to vanish. Also, chlorine outgassing is very slow and can be ignored (in pool sized volumes, in bottles and vials chlorine outgassing is much more important).
 
Just started another shock attempt at dusk. Here are numbers for the first hour:
8:15
FC=39 (No idea how. I measured near 0 in the afternoon and added none until 8:00. 5x182 oz should have only raised it to mid 20s!
CC=2.5

8:50
FC=30
CC=2.5

Where the heck is the the FC going after dark if it's not turning into CC?
 
The chlorine is breaking down organic debris in the water, only some of which registers as CC.

I think it would be good to check if you are using enough R-0870 powder when doing the test. Using too little powder can result in lower than actual FC measurements. Try using say twice as much R-0870 powder than you usually use and see if that affects your test results. Higher FC levels require more R-0870 than lower FC levels do.
 
Starting from FC of 0 (I assume, since it was near 0 earlier in the day and unless washing soda produces FC, it should have been 0!)

Current summary:
Added 5x128 oz of bleach at 8pm
8:15--FC=39;CC=2.5
8:50--FC=30;CC=2.5
9:15--FC=25;CC=1
Added 1x128 oz of bleach at 9:20pm
 
JasonLion said:
I think it would be good to check if you are using enough R-0870 powder when doing the test. Using too little powder can result in lower than actual FC measurements. Try using say twice as much R-0870 powder than you usually use and see if that affects your test results. Higher FC levels require more R-0870 than lower FC levels do.
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I would if I didn't feel like I'm already low on R-0871! (I which the bottle were translucent like the others!)
 

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