Back to chemistry class...

[chem geek]

In "ideal" conditions with proper nutrients in the water and depending on the bacteria, then yes. In a lake, or any ecosystem, a balance gets developed between many different species. So the bacteria are kept in check by protozoa, algae and similar microorganisms all competing for the same food (nutrients) and there are various species that have defenses against each other. There are bacteria everywhere -- millions of them on even a small patch of your skin. The problem isn't in having lots of bacteria, the problem is having lots of the WRONG bacteria (or protozoa or viruses).

In pool water, the wrong bacteria is usually that associated with fecal matter. This includes various common strains of E.coli but also includes pathogens associated with disease including viruses. Though it's not a pleasant image, you really have to think of an unsanitized pool as a toilet bowl (whereas a sanitized pool is clear and clean water). In a lake, river or stream, the various organisms tend to self-clean or at least keep in balance what is dumped into them, but they can certainly be overwhelmed. For example, cholera is caused by a bacterium and can readily be spread even in "open" waters as this was a real problem in India (most people know about the "wells" in England, but those were not open waters). There's an interesting account of this and other cholera outbreaks at this link.

The reality is, however, that the risk of getting disease from even an unsanitized pool is low. It's just that sanitation reduces the risk to near-zero, at least for the easy-to-kill pathogens that low levels of disinfecting chlorine takes care of. The biggest risk in an unsanitized pool is transmission of disease from person to person which is why most serious outbreaks are in commercial pool environments where there are heavy bather loads (i.e. lots of people) rather than residential pools. In a residential environment, the most common problem is with hot tubs where the bacterium that causes hot tub itch is not uncommon and takes somewhat higher levels of chlorine to kill (so using Dichlor exclusively in a hot tub is not wise, even though that is often recommended by the industry).

Richard

[Donna's Poolboy]

PM update...
lost 6 ppm through the day and the ph stayed at 7.2
I took the cl back up to 20 ppm at around 6:00 pm. It's 10:00 pm now and the cl is still at 20 ppm. The water has very little cloudiness, but not quite crystal clear--I'd call it a 95% improvement over 24 hours ago.

I'll post new numbers in the morning.
This is exciting stuff!

[Donna's Poolboy]

Morning update:

FC 16
CC 0
ph 7.5

Water looks great, crystal clear. I added 2 jugs of bleach to take the water back up to 20 ppm. The ph came back up to 7.5, so it looks to me like I'm making progress, yes?

[CarlD]

Sounds like you are doing great!

The bleach in large quantities MAY be increasing your pH a bit--even though bleach has high pH the chem action lowers pH to compensate...mostly.

But the dramatic drops in FC mean you aren't out of the woods yet.

Chem_Geek's advice in a nutshell is: With no FC in the water dangerous bacterial contaminants (most seriously fecal matter) aren't killed and can multiply. Keeping the FC up is critical to keeping the water sanitary.

Pond swimming depends on the pond. First off, they are usually far, far bigger, hundreds of thousands or millions of gallons, so a contaminant is far more diluted. Secondly, a pond is an ecological system, a pool is not. The pond has natural mechanisms to deal with biological matter, such as plants and fish, plus it frequently has a constant exchange of water. Also, there is the natural filtering of the ground: Remember, a pond is where the surrounding ground is SO saturated that the water cannot be absorbed--something like 3x the water is in the ground as is in the pond, and that's a filter.

And, the bottom line is: Just how safe IS that pond to swim in?

[Donna's Poolboy]

Another big drop in FC today...
FC 13
CC 0
ph 7.5

A 7 ppm drop in 10-12 hours is pretty huge. I agree, Carl...not out of the woods yet! I just added 3 jugs to take the FC to 19 and I'll test once more tonight.

Thanks,
Bill

[CarlD]

Bill, just stay on top of it. Test at least 2x a day but 3x is better.

Otherwise, you are doing what you must do. Keep your supply of P.O.P.P. full!

(that's Pool Owner Patience and Persistence)

[mbar]

It took my pool 6 days of keeping my chlorine up to 20 by testing 3 x a day to get my chlorine to stick overnight. Even though by the 3rd day there was no combined chlorine, it was still using it overnight. Finally the last 2 nights it has stayed consistant, so I am letting the chlorine drop down today. The water went from a swamp with green stringy algae last Friday, into crystal clear beautiful water! Even my husband wanted to drain and refill when we opened last Friday, but I knew after reading this board for a couple of years that any water can be cleared with lots of Bleach and POP.