lol, i find myself reading your posts with a french accent.....

I am glad you have found a happy 'middle ground'.

Cheers!!

Shall I read you with a British one?

Heads-up!

Strange occurence here. I believe in a coincidence, but nevertheless.
Customer had a pool running with pucks. PH abyssal (lower than 7), Chlorine level ''high'' (slightly over 5, not enough to erase a DPD test), Alcalinity 0, and calcium hardness 100. Of course his stabilizer level was over 100.

The customer decided to add a large dose of Sodium Bicarbonate. Alcalinity reached 40, pH changed but still remained below 7. However, about an hour after adding the Sodium Bicarbonate (Customer's guestimate), his water became greenish, cloudy. Copper is very unlikely both because of the symptoms and customer not being on well water.

My suggestion was to partially drain the pool, then to shock until the algae clears, then to adjust his parameters. Of course I strongly discouraged the use of pucks for the rest of the season. ''They're great to start a season, maybe for the 3 first weeks, then to use during prolonged absences, but too much of this stuff and you'll re-overstabilize your pool, but in lower quantities stabilizer do a great job(...)'' Take into account pools here are partially drained each year.

My question is: Is it possible an algae bloom was kept in check by a very acidic water?

Algae is usually fairly tolerant of extreme PH levels. Extreme PH will slow down algae growth, but it tend to reduce the effectiveness of chlorine more than it slows down the algae.

Both copper and iron can turn the water green, but they won't cause cloudiness. Cloudy/milky/murky green is nearly always algae.

Thanks for confirmation.

I heard alcalinity 0 meant PH around 4.3, however. Thought it may have put the algaes on hold.

You are right -- a TA reading of zero (i.e. an immediate red in the TA test) means the pH is 4.5 or below. That's pretty low in pH. This paper indicates that the variation of growth rates with pH may be more related to the carbon dioxide level in the water. In this case, a high pH can limit algae growth where algae growth rates dropped as the pH went above around 8.8 or so and plummeted as the pH went towards 9.5. Note that the growth rates did not increase as the pH went towards 7.0 probably due to other factors limiting the growth rate. This link indicates that algae do not survive at very low pH below 4 and that peak growth rates were near a pH of 7.

So it is quite possible that algae were severely inhibited when the TA was 0 and the pH below 4.5. Raising the TA and pH in such an environment would restore positive growth factors so if the CYA were very high then the active chlorine level could have been low enough to allow algae to grow which is what you saw. However, you said that the customer saw a change within a half-hour of adding product, but algae doubling times are on the order of 3-8 hours so I find it unlikely that this was algae growth so quickly. So I don't have a good explanation for what the customer says they saw. If the CH were actually higher and if the pH was overshot, then this could have been calcium carbonate cloudiness, though that wouldn't normally be green unless there was copper in the water and you thought that wasn't the case.

Helpful, as always, chemgeek.
However, from my point of view, it might seems like the very short delay was more of a manner of speech. Might have taken several hours, which is still very short. There's a slight tendency toward exageration when customers relate their problems, they try to make it sound more... i don't know. Spectacular?

Might be an uncouncious belief that if the problem sounds more serious, we will make more efforts into bringing it under control. Will try to be more thorough before advancing information as facts.

Thanks Chemgeek.

Ok, got another one:

PH: 7.6
Bromine: 6 p.p.m.
Alcalinity: 100
Calcium Hardness: 150
TDS: 1000, about 900 over fill water

Customer is using brome tablet with chlorine in it (65BR / 35FC), shock once a while with Potassium monopersulphate (Oxy). Recently, when air jets are activated, water becomes milky white and air barely breathable.

My belief would be an excess of bromamine... maybe some bodily waste forming a grime in the jets, so a good shock *might* bring it back. And I hate to speculate.

Thanks in advance for your replies.

I think you are right, but I'm just speculating as you are. Certainly shocking could be tried to see if it helps. That's one of the downsides with bromine -- you can't measure the bromamine separately so it's hard to know what is really going on.

But are there any known effects for Bromamines?

On a completely other topic, thanks to CaOCl2, I've put my hands on a document called ''Biolabs_Responds_to_phosphates.pdf''. It's an extract from Aqua Magazine, August 2010, where Biolabs DESTROYS the claims made by pool store (which were taught by other members of the industry). I took the time explaining why phosphates weren't really a problem to one of my boss, the message spreaded and we stopped affiliating with Natural Chemistry (although we are still affilliated with Ocean Spa, their pupil, I mean, their SWCG for spas are neat).



I was shocked (not sure it CAN be considered a pun anymore). Seems I am climbing that ladder at an alarming speed. First, CYA test becomes ''almost'' mendatory, then I kick off Nat Chem's butt half-knowingly... give me two years and we'll have a contract with Clorox!

And for you dear friends, a very dim light of hope...

Monobromamine is presumably a reasonable sanitizer, unlike monochloramine. So one doesn't care as much if one has bromamines from a sanitation point of view, but they still smell so it would be good to know when they are there and unfortunately the DPD tests can't distinguish it (i.e. the bromamine reacts directly with the DPD dye just as chlorine and bromine do).

The other downsides to bromine are higher cost, lack of protection from breakdown from sunlight (though it breaks down more slowly than unprotected chlorine), being somewhat weak at oxidizing bather waste (so one occasionally needs to shock with chlorine or use non-chlorine shock if the water becomes dull or cloudy) and having disinfection by-products such as brominated organics (brominated trihalomethanes, THMs) that are more hamful than their chlorinated cousins. That's more of a concern for high bather load pools (and possibly for residential spas where bromine is more commonly used).

That Biolab document has some inaccuracies in it if it is the same as the "Preventing Algae Growth" Word file from Biolab Technical Solutions written by Karen Rigsby. The paper talks about different kinds of phosphates, distinguishing between orthophosphate which is what the phosphate removers remove vs. other phosphorous containing compounds (they don't say it, but most of these are organic phosphates; some are polyphosphates) and how the latter can be used by many species of algae that have enzymes to break down these organic phosphates into the useful form. What the paper didn't say is that the uptake of such organic phosphates is much slower than that of orthophosphate and limits the rate of, though does not completely prevent, algae growth. For example, this paper indicates that bacteria utilize organic phosphates much more than algae (i.e. the fastest algae growth comes from orthophosphate). This paper has similar conclusions where essentially it is the more efficient bacterial conversion of organic phosphates and excretion of orthophosphate that can provide this faster-uptake nutrient to algae. In a pool, however, bacteria are killed very quickly with chlorine so this mechanism isn't readily available -- that is, bacteria aren't converting organic phosphates rapidly to orthophosphate so algae are left to do that on their own, much more slowly. Therefore, concluding that orthophosphate removers (such as lanthanum chloride) do not at least slow down algae growth doesn't make sense and is inconsistent with this and many other scientific papers I haven't listed here (but that I've read).

The BioLab paper does talk about algae storing phosphorous in their cells, but this isn't the point of phosphate removers anyway. They aren't intended to kill existing algae, but only to slow down their growth. With chlorine in the water at sufficient levels, algae is killed (and largely oxidized). PolyQuat is very similar in that it isn't very effective in killing algae in a full-fledged algae bloom. It is far better to use lots of chlorine for that purpose and, if one wants, to use PolyQuat to inhibit algae growth thereby allowing for lower FC/CYA ratios to still be able to kill algae faster than it can reproduce. This is why I put phosphate removers in that same category of algae inhibition, but that chlorine itself is what does the real work of killing the algae. Most algicides, except for copper (which can stain, of course), aren't effective at completely killing algae and even copper requires chlorine to oxidize the algae to clear a pool (unless one uses filtration/clarification to do so). Phosphate removers aren't registered with the EPA as algistats mostly because that costs extra money for little purpose since one can easily market "no phosphates, no algae" though that is, of course, misleading.

The standard phosphate tests only test for orthophosphate, not for organic phosphates. However, testing for and reducing orthophosphate is still one way to slow down (though not necessarily stop) algae growth, thereby allowing lower active chlorine levels to finish them off. I am not a fan of phosphate removers, but I'm not going to say that they are completely ineffective.

We don't promote algaecides in general, let alone phosphate removers, because they aren't needed if one maintains sufficient chlorine levels. Since one needs chlorine anyway for sanitation and oxidation, it might as well be used for algae prevention as well. However, if someone wants more insurance in case they want to have lower chlorine levels or accidentally forget to dose with chlorine, then there is a wide array of choices available at extra cost. We prefer PolyQuat 60 or the use of 50 ppm Borates for that purpose because these have minimal side effects and usually reasonable cost.

Okay, I get it, phosphate removers may serve a purpose.

But the problem here was its marketing. Many other problems from lack of discipline toward one's pool to the simplest overstabilisation were overlooked in favor of 250-500 ppm of orthophosphates! The balance that paper brought made my superiors realize that there are shades of truth... (not sure how it translated).

We do have access to other phosphate removers, if need be, we just weeded out one of them. Our company is built around our good reputation: we couldn't afford this kind of marketing on the long run.

This leads to another topic:

There have been a strange occurrence in two of our customers' pools. The water's cloudy / white as ''flakes'' float in it. When those are left to settle, it form some kind of creamy white ''paste''. Since the problem is recurring and occured in two pools, I checked what was different / similar to point out what's the cause. Here:

Pool A:

Water Source: Well Water
Pool Size: 41808 L (21 feet round, 54 inches high, Aboveground)
Chlorine used: Hypo-Cal 65%

PH: 7.6
FC: 0
CC: 0
CYA: 0
Alk: 100
CH: 300

Pool B

Water Source: Well Water
Pool Size: Not mentionned
Chlorine used: SWCG

PH: 7.4
FC: 0
CC: 0
CYA: 0
Alk: 90
CH: 250

NB: Use of CYA is VERY seldom around here. I work on this. It also explains why FC and CC are 0. Chlorine is still added on a daily basis. Service guy who went to pool B (and made the test) mentionned it looked like undissolved calcium. Sand Filter showed 12 psi. No slippery surfaces.

PS: If informations are insufficient, I will go and get/test myself water samples for these two pools, as well as get the infos on pool B. In both cases, many treatments were tried, with little success. As I think about it... I suspect calcium deposit inside the sand filters (at least for Pool A)...

It will make another thing to check up then. Any other ideas while I'm at it?
[Edit] Service guy's note also says sand's been changed... geez. [End Edit]

There's no question that many pool stores jumped on the "assume phosphates are the problem, and here's the solution" bandwagon and very few look at the chlorine/CYA relative levels.

For the problem pools, the saturation index depends on the temperature, but at 85ºF with the numbers in your post, Pool A is at +0.2 while pool B is at -0.1. Usually, you don't see scaling until the saturation index is much higher, usually +0.7 or +1.0 or so. However, an SWCG cell has very high pH at the plate that is generating hydrogen so could be a source of flaking. If such flakes are seen coming out of the returns when the cell reverses polarity, then that's what's happening (or if you can see calcium deposits on the plates, then that's probably what is happening).

However, in both pools the zero chlorine levels means that algae and bacteria can grow and that can certainly make the water dull/cloudy before getting to a visible algae bloom. If the flakes were like white tissue, then that could be white water mold, but your description sounds more like calcium flakes. If you can collect some (skim from the surface), then if they bubble/fizz when adding acid to them, it's likely calcium carbonate (i.e. scale).

Okay, I got a new one. One of my ''customers'' who is also in the industry, came up with a strange occurence.

Pool is 30'x55', 14' deep, 173000 gallons, pool from 1950

PH: 7,6
Alc: 80
Cya: About 100 or a bit more
Ch: 3.0
CH: 80

CH is unreliable. Tested by drops. Often read 0. Pool is NOT on autofill. Pool doesn't scale, pool is painted, paint seems to be rubbing off easily, and whenever CH is added a few days after it seems to be gone.

Pool runs on chlorine pucks (trichloro) and occasionnal shock treatment using Cal-Hypo.

Would the Concrete pool absorbs CH? Any other clue what might happen to the CH to get low?

Thanks again.

Does the pool get extremely cloudy when the calcium is added? If so, then maybe someone added a phosphate pH buffer to the pool which would cause calcium phosphate precipitate to form (and get filtered out) and prevent the calcium level from getting higher. Normally such phosphate pH buffers are only used in some spas, but maybe someone didn't know what they were adding. This seems doubtful, however, given the size of this pool (I doubt anyone would add that large a quantity of phosphate buffer).

No, I don't think CH will get absorbed by concrete. Any reduction in CH would normally be seen by formation of scaling somewhere and you're not seeing that and the water doesn't seem over-saturated anyway.

PH Buffer might have been the cause. If it was added, it could have precipitated the calcium... So there must have been an higher occurence of backwashes needs. Got it. Gonna ask a few questions to my customer.

I'll avoid using the word ''Phosphate'', if I can, however.

Thanks. Will follow through that info.

Update: I received a promotion. No longer a Pool Store Clerk, but a salesperson in our Fitness Dep. Still helping out a few customers on the side... Subscribing here was the best 30$ investment in the last few years!

Hello Again,

Got a problem to get under control.
Here's the situation:
Inground Pool, 76 000L
PH:7.8
Alc: 100 (not taking into account CYA)
FC: 2ppm
CC: 0ppm
CH: 200ppm
Cya: 30ppm
TDS: 1000

Chlorine used: Cal-Hypo / Trichlor
(Up north we have 3 months of use then we empty half of the pool / Bleach is not as cheap)

Water keeps being milky white, not enough to cover the shallow end, but you can't see the liner in the deep part. A bit slimy. Told him to do a shock treatment. Sand was changed this year, clarifier added, without any effect. Pump running 24h.

Any idea where else to look?

100 Reasons for Cloudy Swimming Pool Water.