trader_4 wrote, on Wed, 25 Jun 2014 08:06:58 -0700:

With 4 floaters, isn't the chlorine through the roof?

I understood everything you imply, as I am familiar with
the increasing ratio of CYA to target free chlorine level
as per this common table:

(Stabilizer) (Minimum FC) (Target FC) (Shock FC)
20 2 3 10
30 2 4 12
40 3 5 16
50 4 6 20
60 5 7 24
70 5 8 28
80 6 9 31
90 7 10 35
100 7 12 39
etc.

There is plenty of full sun here in summer in the NYC area
and with a 48,000 gallon pool, 1 floater loaded with
about 7 tabs keeps the chlorine at about 2 PPM.

I actually only have about 50 ppm CYA, even with adding the
powder, which means I need to target Free Chlorine at 6 ppm.

The question is why you need so much chlorine?

I realize it's not often stated at the pool store, but,
the chlorine number is wholly useless without the associated
CYA value.

For example, with your 2ppm of free chlorine, if you had
a 40 ppm CYA, you'd already be below the minimum, and far
below the target chlorine levels for your pool (based on
my read of the chart above).

I can only hope, for your sake, that your CYA is at or
below 30ppm, which, for a sunny area out here, would not
be enough stabilizer.

I've never seen a pool with more than one floating dispenser,
let alone four.

You haven't seen "my" pool!

Seriously though, I'm welcome and open to ideas, as I can't
seem to keep chlorine in this pool, even though the biological
load is nearly zero (nobody even swims in it lately).

"DannyD." wrote in :

I understood everything you imply, as I am familiar with
the increasing ratio of CYA to target free chlorine level
as per this common table:


Can you post some pics of the labels of the chlorine that you are using?

Zaky Waky wrote, on Wed, 25 Jun 2014 21:30:36 +0000:

Can you post some pics of the labels of the chlorine that you are using?

Here is a picture of the chlorine "I" am using (Costco tablets & HASA liquid):
https://c2.staticflickr.com/6/5527/1...e66fd6c3_c.jpg

But, here is a more complete explanation of what *you* might find on the labels:

1. Liquid chlorine at 12.25% trade percentage available chlorine by volume (aka 10.78% available chlorine by weight, aka 11.31% weight percentage of sodium hypochlorite):
$cost/gallon liquid x 1gallon liquid/9.7pounds liquid x 100 pounds liquid/10.78 pounds available chlorine = price per pound of available chlorine

2. Bleach at 6% weight percentage of sodium hypochlorite (aka 6.17% trade % available chlorine by volume, aka 5.71% available chlorine by weight):
$cost/gallon liquid x 1gallon liquid/9.0pounds liquid x 100 pounds liquid/5.71 pounds available chlorine = price per pound of available chlorine

3. Bleach at 8.25% weight percentage of sodium hypochlorite (aka 9.08% trade % available chlorine by volume, aka 7.86% available chlorine by weight):
$cost/gallon liquid x 1gallon liquid/9.0pounds liquid x 100 pounds liquid/7.86 pounds available chlorine = price per pound of available chlorine

4. Solids & powders (available chlorine is as listed on the package):
$cost/pound solid x 100 pounds solid/?? pounds available chlorine = price per pound of available chlorine

Where the demominator for 99% by weight Sodium Dichloro-s-Triazinetrione, anhydrous, is 64.
And, where the denominator for 99% by weight Sodium Dichloro-s-Triazinetrione Dihydrate is 55
(which is the same chemical as Sodium Dichloro-s-Triazinetrione, typically 85% by wt & 14% water,
available chlorine 55%). But, the denominator can be as low as 36 for certain formulations
(e.g., Costco item #175121, aqua chem Shock Plus 4 in 1 pool shock 24 pack, EPA REG No 67262-27
telephone 800-252-7665).

For trichlor aka trichloroisocyanuric acid or richloro-s-triazinetrione, the available chlorine
varies by weight as listed on the package):
a. Home Depot & Leslie's Pool 99% trichlor is listed as 90% available chlorine.
b. Lowes 95% trichlor is listed as 85% available chlorine.
c. Costco 94.05% trichlor is listed as 84.65% available chlorine.

Note: Sometimes, Dichlor Dihydrate available chlorine is shown as 56% (even though 100% pure product
would be 55.4% and 99% pure product would be 54.8%), possibly because there may be some anhydrous
Dichlor mixed in with the Dichlor Dihydrate (manufacturing processes are not perfect).
Also, most confusing, is that sometimes they leave out the "dihydrate" in the ingredients even
though it is really there. The easiest way to tell is by looking at the % available chlorine.

trader_4 wrote, on Wed, 25 Jun 2014 15:21:36 -0700:

I've never seen that table.
What makes you think it's right?

While it stands to logic in that the more stabilizer you have, the more
free chlorine you need to maintain its effectiveness, I didn't make that
table up.

The original Chlorine/CYA "Best Guess" chart was developed by Ben Powell.
Richard Falk had refined and expanded on that original to produce the
Chlorine/CYA Chart by Chem Geek as described he
http://www.troublefreepool.com/threa...rine-CYA-Chart

The point is that most people don't even realize that the free chlorine
that they need depends on the existing CYA level that they have!

trader_4 wrote, on Wed, 25 Jun 2014 15:21:36 -0700:

what I've seen is a recommended range of 1 -3,
with no adjustment for CYA. I know CYA has an effect, in the sense
that while it stabilizes it, it also lessens the sterilizing
effect if it gets too high.

Exactly.

It's a bit too complicated for me to fully understand,
but, it's all summarized in this chart:
http://richardfalk.home.comcast.net/pool/HOCl.gif

Which is explained he
http://www.troublefreepool.com/threa...ater-Chemistry

End result?

The sanitizing goal is *not* a particular free chlorine level!
It's a particular free chlorine level that offsets whatever
your CYA level is.

trader_4 wrote, on Wed, 25 Jun 2014 15:21:36 -0700:

A lot of this pool stuff is just handed down and a lot of it is
wrong.

I don't disagree.

Take, for example, the pool-store recommendations to reduce
phosphates to prevent algal growth.

Sure, algae need phosphates, but, free chlorine, in and of
itself, kills algae.

On the other hand, I did try to source industrial lanthanum
chloride salt crystals (active ingredient in Orenda PR-10000),
but, failed.

So, if anyone here can get a good price on industrial grade
lanthanum chloride, you can make a killing on the pool stores!

"DannyD." wrote in
:

Subject: Actual price/gallon for 12% Hasa Pool Chlorine (for SMS
and the Silicon Valley) From: "DannyD."
Newsgroups: alt.home.repair,sci.electronics.repair

Zaky Waky wrote, on Wed, 25 Jun 2014 21:30:36 +0000:

Can you post some pics of the labels of the chlorine that you are
using?

Here is a picture of the chlorine "I" am using (Costco tablets & HASA
liquid):


Thanks.

Zaky Waky wrote, on Thu, 26 Jun 2014 07:36:37 +0000:

Thanks.

I made a slight typo on the HASA liquid chlorine; it's 12.5%, not 12.25%,
but the equation is otherwise correct (AFAIK).

trader_4 wrote, on Thu, 26 Jun 2014 05:31:48 -0700:

B - I find it hard to believe it's right, because if you look
at the water quality recommendation from pool standards organizations,
public health depts, etc, I've never seen the chart or anything
that says your high levels of chlorine are needed.

Hi trader_4,

I understand what you're saying, so, we need to look at this
closely, scientifically, and logically.

Both you and I can understand the *logic* of the CYA-to-chlorine
argument. It's why pool stores test CYA in the first place.

The higher the CYA, the less effective any one level of chlorine
is. We all know that, so, at least the "inherent" logic is
underlying the charts.

But is it science?

This technical bulletin lists a few scientific references:
http://www.aquaticspecialtyservices....hbulletin1.pdf

Namely, the following which, the bulletin says, conclude:
"cya inhibits chlorine's ability to kill bacteria".
a) American Journal of Public Health, October 1965, Anderson
b) Applied microbiology, May 1967, Fitzgerald

Yet, we are saying most "official" recommendations don't mention
the CYA level, right?

Here's an 'advisory', that says, essentially, the same thing:
http://www.accu-tab.com/Portals/0/pd...A_Advisory.pdf

So, maybe together, we can flesh this out, to understand why most
official chlorine recommendations don't seem to take into account
the CYA levels.

One potential "error" in our assumptions is that an *indoor* pool
probably doesn't have *any* CYA; so, any "official" recommendation
for chlorine levels in an indoor pool wouldn't be pertinent.

Another potential complicating factor is that, for outdoor pools,
the CYA levels might be "assumed". I don't know, as we'd have to
look at each official recommendation to be sure.

This post is getting long, so let me google for "official"
*outdoor* pool chlorine recommendations to see what I can dig
up to support or disprove the hypothesis.