Re: Need 2nd Opinion on % vs Volume vs $ calculation/assumptuion
![eek! (shock)](images/smilies/shock.png)
Don't want to start a battle here...and I'm absolutely not qualified to really understand the points being made. Formulas I can handle...
For what it's worth...I wanted to add +2ppmFC to my pool today (reading was3ppmFC). ThePoolCalculator said: "16oz of 10% bleach will raise 2ppmFC". I mixed in 2cups of what I have, in my yellow jug, and tonight my reading was up to 5ppmFC.
For What It's Worth...I use a Taylor k-2006 and run 10ml (0.5ppm/drop) samples on my pool water. I 'did' do a 0.2ppm test on my tap, because I 'know' that one is pretty low. As for Carl's test method, I started with a 0.2ppm test, but gave up after 20drops. I can't afford to waste my reagent like that. So I ran a 0.5ppm test on that water...so there is a +/- 0.5ppm resolution on that "%conc" (or whatever) reading.
To be fair, I never asked TheCalc what 12% amount I needed to go +2ppmFC...and with only a .5ppm resolution...I might not have noticed the difference anyway.
To me, Carl's testing method seems to work and makes sense since it's a titration method, just like the FC sampling I'm doing anyway. If this test ultimately gives me a reliable way to ensure proper dosing...I'm happy with it.
The way I understand it:
(I rounded the numbers, and ignored background FC, for simplicity)
- 1ml of my yellow jug = 10ppmFC in 10liters of 0ppmFC water.
- I only want 2ppmFC so I only need 1/5ml...so then:
- 0.2ml of my yellow jug = 2ppmFC in 10liters of 0ppmFC water.
- My pool is 20000liters (or...2000 x 10liter buckets)
- to get + 2ppmFC in my pool I need to add 2000 shots of 0.2ml from my yellow jug.
...or 2000 x 0.2 = 400ml (13.5oz) from my yellow jug.
That's close enough for me, and it seems to have worked...
So...does your's disagreement matter? ...since all this 'stuff' is labeled as % anyway? Even if the testing doesn't work out to a 'true %' reading...it is an indication of some sort...and that 'relationship' will translate across all the different 'stuff' available. 12% is Carl's 10...4% is Carl's 3.33333 ....as long as it's consistent...it's a reliable yardstick.
...let's not argue about it, if it's only a 'tomato' or 'tohmato' type of thing...
-or-
let's get el-super-brain
ChemGeek to referee this discrepancy...and help nail it down to ultimately come up with a take-it-to-the-bank solution to help everybody verify their 'stuff', to ensure cost effective dosing, maybe help protect us against unscrupulous vendors and just pile on another good reason to be part of this great forum and what it stands for.
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My whole point for this thread was to try and ensure my thought process was accurate in trying to determine the most cost effective way to chlorinate my pool.
As I have thought more about it: 'splitting hairs' could come down to how much time & gasoline I have to spend and how much storage space I need to achieve this chlorination. (Walmart is on my way home from work, would only cost me 15minutes of 'free' commute time, but easy-to-handle jugs take up valuable space in my shed...and my recycle bin.)(The Pool Store is completely out of my way, pretty much for any travel I do. So that's a 30-45 minute round trip + gasoline to fill up (a $15 cumbersome-to-handle jug I had to purchase) x-number of times a season, but is pretty compact in the shed.) There's still a few hairs to split if I want to get anal about it.
I *really* should grab one of those Walmart jugs and run Carl's test on it, to see what it is...and compare it from there. I'll never be able to control the 'freshness' factor and I'm certainly not going to test each jug...but maybe after a few random tests...I can get comfortable with what each option offers and put that part of the equation to bed. Also, I'm a first-timer, at the end of the season, with minimal bio-load...and I 'still' haven't made up a log book....so I can't reasonably expect to determine the frequency/amplitude of chlorination...which will have a huge impact on the whole 'hair splitting' process.
...and then...there's this whole "cal hypo" option that giroup01 mentioned...and the great "cost per ppm" comparison suggestion...which I think I'm doing by going with Carl's method. This way, I can somewhat-reliably nail down how much of "whatever option" I need to raise my pool by 1ppm...and see it's ultimate cost.
I think my head is going to explode ![tongue out](images/smilies/tongue2.png)
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Oh...and thanks again for all yous's help. The members of this forum all rock!
I especially appreciate the intelligent on-going discussions and apparent lack of ego...unlike the various motorcycle forums I used to frequent.
Last edited by Sponge1971; 08-29-2011 at 01:13 AM.
Reason: Relate back to my original reason for this thread
5300 Gallon (15' x 52" composite & aluminum - AG)
(Not Salt Water - Liquid Chlorine - Trying BBB...)
Sta-Rite Mod3 60sqft DE Filter (with 8lbs charge) - Sta-Rite 2" Dyna-Wave Pump (<<< L-O-V-E )
All 2" plumbing (except 3" suction line, modified skimmer) - Two 1.5" returns at 180degrees apart (skimmer return piped down to floor)
"15' round 5.1K gal AG pool; ~10% liquid Chlorine; Sta-Rite Mod3 60sqft DE Filter DE filter; Sta-Rite 2"" Dyna-Wave Pump pump; 11hrs; Taylor K-2006
'drops' FAS-DPD Chlorine, ; utility water; summer: ; winter: ; iPhone; PF:24"
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