New Pool Owner Pool Has Been GREEN for a Month

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cya

Postby pool tech » Sun 19 Aug, 2007 00:08

Honestly I don't worry about the cya level in residential pools only commercial where regulations want it below 100ppm. I have found no corralation between cya levels and chlorine consumption. I can have a pool with 80ppm cya and one with 180ppm cya and can keep both between 3-5 ppm chlorine with the use of 2-3 tabs per week without any cloudiness or algea growth.


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Pool Has Been GREEN for a Month

Postby chem geek » Sun 19 Aug, 2007 03:10

pool tech,

I'm getting confused by some of the information you've given so please help me sort this out. From your posts, the procedure you use is to check the water chemistry and if the CYA isn't 80 ppm, you raise it (so the pools you service all have at least 80 ppm CYA) and when algae appears to be starting (probably dull or cloudy water, before it turns full green) you raise the FC to 10 ppm as that works for algae problems in most of the pools you service. If the phosphate level is high, then you use a phosphate remover which will work in those pools. If none of that is the case and doesn't work (along with checking the filter and circulation, etc.), then the water is old, has too high a TDS, and a drain and refill should be done.

You said you service 100 pools per week, including commercial pools, so a mix of residential and commercial pools. You say you've serviced 30,000+ pools which confuses me. Aren't the same 100 pools serviced each week as more Trichlor needs to be added, filters cleaned, pool surfaces brushed, etc.? Where does the 30,000+ come from? You said you maintain 100 pools so is the larger number your cumulative experience over the years (i.e. 100 pools per year times 30 years)?

You said you keep the FC at 3-5 ppm and the CYA at 80-100 ppm, but later said that this is only for commercial pools that can't have more than 100 ppm CYA so residential pools can have more. So how do you keep the CYA below 100 in the commercial pools? I assume those tend to be larger pools, at least 15,000 gallons and probably 30,000 gallons or more -- is that correct?. In such large pools, there isn't a lot of dilution, even with sand filter backwashing, so how do you keep the CYA below 100 if you are using Trichlor all the time? Do you switch to an unstabilized source of chlorine or do you do a partial drain/refill every few weeks to keep the CYA below 100?

For the commercial pools, since they are all at 80-100 ppm CYA, there isn't going to be any correlation available between CYA level and algae development. So it's the residential pools that are of more interest. So what you are saying is that when the water starts to turn (look dull or cloudy), you test the water chemistry including CYA, right? And have you found that as many pools with very high CYA well over 100 ppm get algae as frequently as pools at 80 ppm -- both with comparable FC levels? Now I would expect that the pools with lower CYA levels would be those that have more dilution -- so smaller pools with sand filters backwashed weekly, for example. Larger pools with cartridge filters would more likely have higher CYA levels. So looking at it that way, do you see any correlation between which of those sets of pools get algae more frequently?

And I want to just make sure -- you aren't using any algaecide in any of these pools, correct? No copper, PolyQuat, linear quat, or borates (Proteam Supreme, etc.), correct?

2-3 Trichlor tabs (if the 3" 8-ounce weight variety) per week in 15,000 gallons would be 7.3 to 11.0 ppm FC and 4.4 to 6.7 ppm CYA per week. That's 1.0 to 1.6 ppm FC per day which is somewhat low for full day exposure to sunlight and some bather load. When you said 2-3 tabs per week are these for smaller pools or pools in partial shade or using an opaque-to-UV cover? Also, after 6 months the CYA would rise by 114 to 174 ppm less whatever is diluted. If you aren't measuring such high levels, then is this due to lots of backwashing, splash-out, intentional dilution (partial drain/refill) or much larger pools than I assumed?

Since you mentioned the part about old water and TDS, the pool industry used to think that high TDS was a problem, but in fact the high TDS was just a proxy for having a high CYA level (and usually meant higher CH and salt levels as well). Older water usually had higher CYA levels if stabilized chlorine was always used and the pools didn't have lots of dilution (lots of dilution would be found in smaller pools with frequent backwashing or splash-out, for example). You said, "I can have a pool with 80ppm cya and one with 180ppm cya and can keep both between 3-5 ppm chlorine with the use of 2-3 tabs per week without any cloudiness or algea growth.", but the question isn't having pools with different CYA levels that don't get algae, because there are several factors needed to have algae. The question is whether the pools you have that DO start to turn (and you have several of those each year) have lower or higher CYA levels -- both those pools that get "fixed" by 10 ppm shocking as well as those pools with high phosphate levels where you then use a phosphate remover. So have you found that the residential pools that started to turn (regardless of phosphate level) were both low and high CYA levels in similar numbers (in proportion to the CYA levels in the residential pools)? Or did it appear that pools that couldn't get fixed with 10 ppm FC had phosphates and high CYA both?

I'm just trying to reconcile what has been reported by residential users on multiple pool forums (and Ben's experience with commercial pools) where most pool users reporting algae either had minimal or no chlorine (i.e. < 1 ppm FC) or had high CYA with too low a relative FC (all were below 7.5% of CYA level) including pools with very high CYA (> 150 ppm) where even seemingly OK FC levels of 3-5 ppm did not keep away algae -- and shocking with 10-15 ppm FC was not enough. Because phosphates are a nutrient for algae, it's easy to just write this off as high phosphates, but even pools with high phosphates (3000+ ppb) have had algae controlled with chlorine levels scaled to the CYA level for almost all users (only 3 out of several hundred pools that developed algae had recommended FC/CYA ratio levels and we're not positive about all three -- one had 10,000 ppb phosphates so could require more than the recommended FC/CYA ratio) so there has to be more to the story than just phosphates. I suspect that many of your algae-free 5 ppm FC, 80 ppm CYA pools actually have similar high phosphate levels to those that got algae at 3 ppm 150 ppm CYA.

Richard
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Postby mr_clean » Sun 19 Aug, 2007 09:51

I have been reading all this and notice a few things:

everybody but pool tech must be from the mid-west or east but not the west coast.

everyone seems to be using sand filters

almost everyone seems to have 20,000 gal or below pool sizes

Phosphates do not seem to be an issue but on west coast, I am wondering
do most backyards not have alot of plant/tree life?

Does anyone actually have a test kit for phosphates?

How many hours a day does everyone run their filter winter/summer?

all pool stores except on west coast are just tryin to rip you off or know nothing at all.


BBB is going to start being sold by AARP to help anyone 65 or older pinch another penny (sorry I thought it was funny not tryin to spread hate)
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Postby Guest » Sun 19 Aug, 2007 19:18

If you look at the locations of pool users and service techs in postings on this and other forums, you'll find that they are all over the country, including the west. I live near San Francisco, for example. In my county north of S.F., we have to use cartridge filters since we are under water restrictions and water is very expensive as well.

There are some residential pool users with 8-10 foot deep pools that are larger (20' wide or larger) and are from 30,000 to 45,000 gallons, but you are right that most have inground pools around the 15,000-25,000 gallon range and above-ground pools, including Intex are smaller at around 7500-15,000 gallons (though there are exceptions). It's not surprising that there are more smaller above-ground pools as these are less expensive.

Phosphate removers are promoted in pool stores around the country, but I suspect that phosphates are found in most pools. It's just that those with sufficient chlorine levels don't get tested for them so you only see the "problem" pools and by definition they have to have at least some phosphates or else the algae won't grow.

AquaChek makes a test strip called the AquaTrend Phosphate test and Taylor makes a K-1106 kit for testing phosphates. Both test up to 1000 ppb but through dilution could test higher.

Phosphates do not seem to be an issue but on west coast, I am wondering

I don't think pool run times are relevant since pump sizes and flow rates vary. What's more relevant is the number of turnovers per day. Most pool users report one turnover per day but how much is really needed is a function of how much debris and organics get into the pool as well as pool circulation (above ground pools without a floor drain tend to have poor bottom circulation though pointing the return diagonally down and to the side helps create a circular motion).

Richard
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Postby chem geek » Sun 19 Aug, 2007 21:50

Sorry -- I forgot to log in on that last post. You are right that a count of filter types on the forums (which is not necessarily a good statistical sample) does appear that sand is the most common, then DE and cartridge, but it seems to vary based on region. For cleaning efficiency, DE is best, then cartridge, then sand (generally), but people can add some DE to their sand filters (add some to the skimmer to get the PSI up a couple) and get the best of both worlds -- the convenience of backwashing sand filters with the filtering efficiency of DE (you need to add more DE to the sand filter after backwashing, but since it's such a small amount it's pretty cost efficient).

Richard
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Postby mr_clean » Mon 20 Aug, 2007 17:50

I don't think pool run times are relevant since pump sizes and flow rates vary. What's more relevant is the number of turnovers per day. Most pool users report one turnover per day but how much is really needed is a function of how much debris and organics get into the pool as well as pool circulation (above ground pools without a floor drain tend to have poor bottom circulation though pointing the return diagonally down and to the side helps create a circular motion). [quote]

Run times to me come into effect with algae problems when:

how old equipment is, you would be suprised

what size equipment

is filter dirty

the debri amount in pool

how pools are shaped and return lines

how many return lines there are

how much it is being used

what time of year-heat

If it's above ground some have one returnline in the middle of wall with no control also tiny cartridge filters

I am not trying to say just green but to me more common yellow which will turn to green.

No matter how well we dial in chemicals if it does not filter long enough chemicals get used up.

As equipment gets older run times can lessen

I was also thinking how many of these people with problems brush enough and correctly as I have seen algae grow in pools with chemicals perfect. I am sayin corners of steps ledges etc. it spread's
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Postby chem geek » Mon 20 Aug, 2007 18:46

Yes, you're absolutely on the money with regard to circulation. I just meant that running 16 hours a day at 25 GPM is not much different than running 8 hours a day at 50 GPM if circulation is normally OK. Both have the same turnover rate, but it's true that in pools that don't have good circulation, that more time can somewhat make up for that by giving the poor circulation areas a little more mixing and less "stagnant" time.

I have found that using GLB Party Blue dye is a good way to see the circulation in a pool (plus the pool is a fun blue for a couple of days). Another is to get a water sample for measuring chlorine by turning the tube upside down and slowly sample water in an area of interest turning the tube upright when at the right depth (and doing all of this when the pump is off helps, too). One can also use a turkey baster to carefully collect a sample (this is also useful for collecting suspect algae to view under a microscope or to settle in a jar for "feeling" it).

And you're also right on the money with regards to brushing. That helps a lot to prevent biofilm formation and to expose any surface algae to chlorine. This is most especially important in preventing black algae which grows very slowly but takes advantage of a lack of brushing by forming a slime layer. I brush my pool once a week -- it forces me to get some exercise (remember, I'm pretty much a nerd)!

Richard
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Postby canadug » Thu 23 Aug, 2007 11:33

I had an issue with algae in my pool for close to a week. I shocked the heck out of the pool but the green didn't go away. Two days later I shocked it again. Nothing changed. Backwashes did nothing for it. I did some research on the internet and figured out that the algae was dead but too fine grain to be caught in my sand filter.

I used 200 MLs of a liquid clarifier that made the smaller particles of algae join together. The 1 L bottle only cost about $12 (CDN) and did the trick. I then vacuumed the pool each day and then did a backwash.

Hope this helps!

I found this url really helpful:

www(dot)wikihow(dot)com/Determine-Which-Pool-Algaecide-and-Pool-Clarifier-Is-Best-for-Your-Swimming-Pool

Here's a blurb on flocing agents.

www(dot)poolstore(dot)co(dot)uk/shopscr16.html
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Pool Has Been GREEN for a Month

Postby chem geek » Thu 23 Aug, 2007 12:56

Thanks for the tips. When a pool doesn't clear on its own, especially in an above-ground pool without a floor drain, then using OMNI Liquid Floc Plus will consolidate particles and have them fall to the floor where they can be vacuumed to waste. A clarifier which consolidates particles to be filtered out only works well when the circulation is good. And you are also right that if the filter isn't doing a great job, that a clarifier can help, but for a sand filter you can also add a little DE to it and get the best of both worlds (see this post ).

In a situation where shock does not turn the pool from green to a blue-green cloudy color, then there is more than algae in the pool. Algae will not remain green after exposure to proper shock levels of chlorine. The green chlorophyll will literally get bleached out. See this link for what a pool with algae that gets shocked looks like. If the pool is a stronger green after shocking, then it is more likely that there is copper in the pool and that the shocking with a hypochlorite source of chlorine has raised the pH and precipitated copper carbonate (which is blue-green -- see this link ).

At any rate, a clarifier or floc will speed up the process, but if it's truly just alage and not copper in the pool, then chlorine alone will clear the pool over time, as shown in the link, but it does require more patience and good pool circulation.

Richard

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