Back to chemistry class...

[Donna's Poolboy]

Rats! Just when I thought everything was great, I've hit a snag. Crystal clear water after the initial open, then we had a chilly spell here where we didn't use the pool for 3 days (covered for all 3). I added a jug of 6% bleach each day which was my routine from last year, but when I pulled back the cover tonight...cloudy water! Here's my numbers:

FC 0
CC 0
ph 7.2
alk 160
cya 70
cal 220
times my 3 year old told me "dad...that water's DIRTY" 62.5

Obviously, there's no chlorine in the water and I noticed that my ph (which was stable at around 7.6) had fallen to 7.2. After thinking about it and poking around in other posts, I have a GUESS as to what I did wrong:
After first opening the pool I raised the water to shock level (20 ppm) and waited for it to clear up (which it did in about 4 days). However, I probably didn't keep it at shock level long enough. Does that make sense? That's about all I can come up with. The water is cloudy but not green.



Here's my plan:
I added a bunch of bleach and took the cl back up to 20 ppm.
I'll keep it at that level for 2 or 3 days or until there's no drop off overnight. I didn't add any Borax yet...it was stable so I'd hate to screw with it too much. I figure I'll tackle the chlorine problem first then see what the ph looks like afterwards. Will the ph come up after you shock the water?

[CarlD]

OK,
pH of 7.2 is a little low but not so low you need to worry. In fact, chlorine will be more effective there. I'd leave it for now.

Yes, keep your FC at 20--check it two to three times a day, vacuum everyday, preferably to waste, and brush it everyday. If you have an robotic cleaner like a Dolphin or Aquabot that climbs and brushes the walls, you can use that to vacuum and brush.

Otherwise your plan is fine.

When you "get there", if pH is still at 7.2, try raising your pH by aerating the water rather than adding Borax as your T/A at 160 is a little high (but still OK for vinyl) and will otherwise go up even more as pH rises. Only raising pH by aeration will prevent that.

Aerating can be just by leaving the pool uncovered, adding a sprayer or fountain, or a gang of splashing kids--but the last is ONLY after the water is sanitary again.

[mbar]

Just a note, sometimes keeping the pool at shock levels for a couple of days is not enough. You must check at night and see if you are losing any chlorine overnight, because sometimes even with a cc of 0, if the pool is using chlorine overnight, then it is fighting something that will take hold if you don't get rid of it completely. I have had to keep my pool at shock for 6 days so far after opeining. My water is clear, no combined chlorine, but still losing some chlorine overnight. Each night it loses less - so I think it is almost ready!!:)

[Jeffski]

Aerating can be just by leaving the pool uncovered, adding a sprayer or fountain, or a gang of splashing kids--but the last is ONLY after the water is sanitary again.

Are you saying you wouldn't let kids swim with the FC down to zero?

[Ohm_Boy]

Are you saying you wouldn't let kids swim with the FC down to zero?
Well, I sure wouldn't. With a zero FC, there is nothing sanitizing the water. Maybe it *JUST* hit zero a few seconds ago, and nothing is alive in there, but more likely it's been at zero long enough for some serious bacteria to grow.

Either way, once the bird droppings hit, and whatever airborne nasties settle in from blowing over the neighbor's trash cans, and swimmers start tracking in dirt and GodOnlyKnowsWhatElse, you have an unhealthy bacteria culture situation in a hurry.

Remember that it's not just about algae. Its about sanitization.
Algae is just nature's way of trying to keep you out of an unsanitary pool.

[chem geek]

Bacteria have a generation rate, which is the time it takes to double in population, of from 15 minutes to an hour depending on species and conditions. If it's 15 minutes, then in 8 hours 1 bacterium may become over 4 billion bacteria. Even if it's the generation rate is 1 hour, then in 24 hours 1 bacterium may become over 16 million.

[EDIT] Algae have a generation rate of from 4 to 8 hours which is why it seems like it takes a while for algae to appear, but it grows (in ideal conditions) by a factor of 8 to 64 over a 24-hour period. So it seems like it starts out more slowly, but then appears to "bloom". [END-EDIT]

Richard

[Jeffski]

So a pool that has dropped to zero chlorine can be more unsanitary than a lake within 24 hours?

[Donna's Poolboy]

Here's an update...
I lost about 6 ppm of chlorine overnight and the ph remained at 7.2
The water is MUCH clearer (can see the drains in the 8' end and the liner pattern) but still somewhat cloudy.

Each jug of 6% bleach raises my cl by 2 ppm, so I added 3 jugs and I'll check it again later today. The pool is in full sunlight for the rest of the day.

I should have mentioned that all the heavy debris has been vacuumed out (to waste) and I brushed the walls several times right after we opened a couple weeks ago. The only sediment on the bottom is the minimal stuff that will collect around the seams opposite the return jets overnight. Should I still vac to waste?

Looking ahead to the aeration part...we've got a couple fountains at the deep end. We usually only turn them on when the kids are swimming. But if I leave them on for a good portion of the day, that will aerate and raise the ph?

Thanks,
Bill

[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 (http://www.theplumber.com/plague.html).

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! :rolleyes:

[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.

[Donna's Poolboy]

Okay...here I am about a week into my pool's voracious chlorine appetite problem. The last 2 nights, the water lost 2 ppm overnight. However, between 4:30 am and noon today, the cl dropped by 6 ppm and the pool is just now getting into full sun. A 10 or 12 ppm drop during the day hasn't been uncommon. I'll bet this thing has gobbled up 40 jugs of bleach since last week.

It's hard to tell if I'm making progress. The water is crystal clear and the ph has been stable since this weekend. I've been diligent about vacuuming, testing and adding bleach to keep the cl at 20 ppm. I've got a nylon in the skimmer, so I've only backwashed once. (Or, should I be doing it daily?)

I bet other people who've had this problem can relate to the feeling of "I MUST be doing something wrong." You start questioning everything--maybe I got a bad batch of bleach, maybe my reagents are bad, maybe my neighbors ARE right and I DON'T know what I'm doing, maybe the people in charge of the forum have stock in Chlorox... (by the way, the bleach is fresh and the reagents are all new!)

Here are my latest numbers
FC 20
CC 0
ph 7.5
cya 60
alk 160
cal 220

So this is the part where I throw my sob story and my boo-boo face onto you guys (and gals). I'm hoping that there isn't a serious problem. I'll be waiting for a sympathetic shoulder and a hankie to dry my crocodile tears. In the meantime, I'm off to WalMart. They're having a sale on liquid patience. Wha'd ya think...4 maybe 5 gallons?

Thanks,
Bill

[CarlD]

If your pool is staying so clear, you may want to just see if you can hold your FC in the 5-10 range now.

Otherwise your numbers look fine.

[mbar]

I have been having the same problem. It is two weeks now, and my pool is using extreme amounts of bleach. I thought it was getting better, then today it dropped 12ppms:eek: I think it may be all of the pollen and caterpillas falling into the water. I keep getting no cc and the water is clear, but I don't really want to drop the chlorine down low until it is holding overnight. I have been trying to keep it at 15, but may try boosting it up to 20 again for a time to see if that is what it needs. My cya is only at 30. I will keep you informed:)

[Donna's Poolboy]

Marie-
I was starting to wonder about the pollen. I just checked the skimmer sock that I replaced yesterday and it was PACKED with what I'm assuming is pollen skimmed off the water. Pollen is an organic material...maybe that's contributing to the chlorine loss. It dropped 1 ppm overnight, but I've lost around 12 ppm in 24 hours. However, the water is crystal clear.

I read Ben's spring start up tips:
http://www.poolforum.com/pf2/showthread.php?t=190
Although I didn't lose all my cya over the winter, I did drop from 100ppm to 60ppm. I wonder if that is contributing to the radical loss of cl.

[chem geek]

If your CYA drop was due to bacteria consuming the CYA, then that produces ammonia so that will consume chlorine very quickly (and make combined chlorine go up very fast until breakpoint and eventual breakdown mostly from sunlight).

Every 1 ppm of CYA that gets broken down to ammonia (and carbon dioxide and carbonate) requires 2.5 ppm FC to fully break it down (it's not 10x due to the fact that the CYA is a much heavier molecule so the "ppm" represents much less substance than "ppm" of chlorine).

If all of your 40 ppm CYA loss was due to consumption by bacteria, then it would take 100 ppm FC cumulatively to clear your pool. I suspect that at least some of the CYA loss may have been due to dilution from winter rains so your total chlorine consumption wont' be 100, but it would be interesting to know what it ends up being. Be sure to let us know.

Richard

[Donna's Poolboy]

Richard-
I didn't keep track of how many gallons I drained for winter close, but it was between 12"-18". Factor in rain water and fresh water that I added after vacuuming to waste at spring open, and I've got a large volume of "new" water without any cya. Is there I test for the presence of ammonia (other than smell)? I went and counted and we've gone through almost 50 bottles of bleach as of today (1 jug of 6% raises the fc just shy of 2 ppm). So we've run almost 100 ppm FC. But it took less than 48 hours for the water to go from cloudy (couldn't see the drains in the 8' end) to crystal clear.

Do you have any opinion on the "pollen theory" and if it's playing a role in this?

Last year on a sunny day with light swim load (me and 2 potty-trained kids for an hour or two), I'd typically see the pool burn 2 ppm.
Cl consumption is slowing but still high. From 4:30 am until 4:30 pm I tested the water 4x and saw a 5 ppm drop. Yesterday for the same time period it was about 7ppm drop.

This is our 3rd pool season but first year opening with BBB and I'm assuming this isn't typical. I'm trying to identify if there's something I did wrong when opening, closing or somewhere else. I faithfully adopted Carl's "5 minutes a day" mantra last season with perfect results, so I feel like I'm letting him down!;)

You guys have all been a great help!
Thanks,
Bill

[chem geek]

Though it is possible for the chlorine to get consumed by pollen quickly, I would be surprised if it as fast as combining with ammonia or combining with algae, but I don't have experience with pollen so it's certainly possible. The rate of reaction is partly going to be related to the surface area to volume ratio so very small items will consume chlorine more quickly than larger ones, assuming the same total volume. Pollen is pretty small, but I would have thought it would have remained clumped (and I'm probably wrong about that). Of course, you've been dealing with this over many days so that's plenty of time for chlorine to combine with pollen, I would think.

As for detecting ammonia, probably the easiest thing to do is to measure the Combined Chlorine level very soon after adding the chlorine. Chlorine combines with ammonia VERY quickly so that in a matter of seconds it should be fully combined (it won't be at "breakpoint" -- that takes far longer). So, taking a sample of pool water upon opening and adding some chlorine to it (not too much -- say 3-5 ppm FC) and measuring CCs will tell you you've got ammonia. Even if it's after opening, if you do a "before" and "after" of FC and CC measurements then if the CC almost immediately develops (i.e. add FC gets nearly fully converted to CC), then that's almost certainly from ammonia. As for smell, you won't smell the ammonia that much, but after you've added chlorine you should smell chloramine and it won't be a "clean" smell like bleach.

Anyway, you are doing just fine and shouldn't blame yourself. If you have a high CYA level upon closing and the chlorine level gets to zero, then you may end up with a LOT of ammonia upon opening. So the only options are 1) not to have the CYA as high upon closing, 2) maintain chlorine levels through the winter (if possible), 3) add PolyQuat 60 upon closing (do this AFTER shocking with chlorine when the FC level drops back down a bit -- according to Buckman Labs). The PolyQuat will prevent algae from forming, but probably won't do much about CYA getting converted to ammonia from bacteria (unless the PolyQuat inhibits bacteria -- it just might hinder them through the same "clumping" and ion blocking mechanism that occurs with algae, it just won't be quick).

Richard