Bartier Disinfection Index

[smallpooldad]

Any views on this index (link below)? If it is useful? If so can Ben's excellent calculator for CYA be adjusted for shocking?

Is it correct or not, that temperature also has an effect on the strength of chlorine; or are the numbers not that meaningful?

I created a simple excel spreadsheet and if you run the numbers on a pool with 70 CYA, 3 FC, and a pH of 7.9 it is scary. Looks like all the people I know in Hawaii who have saltwater pool and stick to these numbers need to buy life insurance. "I'm swimming in my own private ocean, my dear." This maybe true but an ocean of what?


http://www.caromal.co.uk/Resource%20Page%205.htm

Looking forward to your replies.

[waterbear]

In the pH range of 7.4 to 7.6 the cholrine is aprox. 50% as hypochlorus acid (actually 52% to 42%) so this is just showing how important it is to keep the pH in line along with the FC and why both need to be tested for more frequently than the other tests!

Your pH of 7.9 is out of accepted range. 7.2 to 7.8 is considered acceptable with 7.4 to 7.5 condsidered 'ideal'. CYA will lower the effectiveness of chlorine but it will keep it around longer in the sun. It still works but not as well as hypochlorous acid does.

[smallpooldad]

Thanks Waterbear,

I may have confused you by posting those numbers. They are more typical of our local saltwater pools, here in Hawaii. Does this mean all the rich people are done for?

Mine is as follows:

Plaster pool (no salt)
CYA 40
FC 5
ALK 100
pH 7.4
Calcium 260
TDS 740

[duraleigh]

Guys,

Ben's philosophy from the beginning has been to keep general pool maintenence within reach of the average person......this post won't help.

This belongs over in the "techno-geek" section of the China Shop forum!
I sometimes wander over there and read some of the postings, but I'm afraid most of them are over the head of this 'ole country boy.

[waterbear]

All the Bartier Disinfection Index is saying is that your pH is important at how well your chlorine works and that too much CYA is a bad thing. It also gives a disclaimer that it is most usefull on commercial pools that are having problems!
If you keep your numbers in line you are following it automatically!

Salt pools with a genterator seem to work better with higher CYA and lower FC levels (WHEN the pH is kept in range!) because of the way the chlorine is introduced into the pool (or so I've been told by the Tech Support rep at Goldline Controls).

[smallpooldad]

Duraleigh,

I'm not sure that safe sanitization levels belong in the China Shop forum.

I do agree with you that keeping it simple is good.

Adding two numbers and subtracting one is hardly major programming, even for Good Ole'Boys.

It might help by reinforcing Ben's calculator with a simple scientific index keeping those persons healthy who are out of range especially the high CYA, low Cl and high pH persons who own saltwater pools of which there are many here in Hawaii.

This persons are often suspicious of anything but pure science, I live next to one such person. But then again you may be right, even that might not work with them as Voltaire said, "A fool will not listen and a wise person does not need to know." In the middle I have always believed that there are the uninformed like me that is why I visit this forum.

Aloha

[waterbear]

It might help by reinforcing Ben's calculator with a simple scientific index keeping those persons healthy who are out of range especially the high CYA, low Cl and high pH persons who own saltwater pools of which there are many here in Hawaii.

Aloha

Yes, the CYA level in a Salt pool is high for the FC level but the chlorine is being introduced into the water at such high concentrations in the cell that it is constanly being superchlorinated when the cell is generating. Comparing this to a pool being manually chlorinated is comparing apples to oranges.

As far as pH goes. If they are letting their pH get up to 7.9 that is just bad pool maintenance since EVERY SWG manufacturer I have ever seen recommends keeping the pH at 7.2 to 7.6, some even specify 7.2 to 7.4! The pH, as you have seen with the Bartier index, is the MOST important factor.

[smallpooldad]

Good point.

Sadly, they often maintain their pools once a week with a pool person and I'm not sure if the pool persons are trying to save money on chemicals or just not visiting enough.

That is why the results are as described. The natural tendency in Hawaii is for the poolwater to rise rather quickly to a pH of 8.0 in most pools, keeping it at 7.4-7.5 is a major undertaking, I know I do it every day.

Anyway I'm giving up on saving the world.

But I did find it interesting that as I keep my pool sooooooo clean that my eyes were irritated slightly when swimming, could not understand why. It seems that my chlorine level is a tad too high using this index. So I learnt something new and am going to adjust accordingly.

Aloha and thanks for your help.

[mwsmith2]

Any views on this index (link below)? If it is useful?

Well, there is a relationship between pH, temp, Cl and CYA. It's true as CYA and pH climb, the 99% kill time increases. Is this one correct? Who knows, I'd have to check in to it further. Ben might be able to provide some insight.

If so can Ben's excellent calculator for CYA be adjusted for shocking?

Well, first off, it's not Ben's calculator, it's mine. (unless you are refering to his "best guess table, of course) Until this Bartier index is proven out, I'm not putting it in. I'd just hate to steer people in the wrong direction. The basic idea is consistent with the actual science I've seen, but I'm just not sure how consistent it is.

Michael

[PoolDoc]

If you'll go to Bartier's page, you'll see the display of the simple HOCl / -OCl curve, which correlates HOCl concentration to pH. His index is based on this curve. There are all sorts of problems with that.

1. The assumption that sanitation is provided by HOCl, and not -OCl, is not supported by field research. HOCl *is* a stronger sanitizer under SOME conditions than -OCl, but this fact doesn't always correlate with what's observed in actual pool simulations.
2. The simple curve he works from does NOT apply to outdoor pools with stabilizer. In those pools, the curve is radically different, and far more complex. One of my users is developing a *very* complex Excel spreadsheet that calculates HOCl, -OCl and other levels, based on CYA, DPD chlorine, pH, temp, & ionic solution strength. The calculation involves iterative simultaneous solution of 15 (I think) equations. My 'best guess' table is based on some *rough* approximations of this information, along with some adjustments based on field experience.
3. Bartier generally assumes that some of the simplistic metrics available to the pool industry are literally and absolutely applicable to actual pools, in spite of the wealth of information to the contrary. His pages are useful, if compared to information provided by Biolab or by pool dealers, but still leave much to be desired.

All in all, I don't see any particular benefit from this discussion for most of the newbies coming here . . . so I'm moving this to the China Shop.

Ben