New Pool Owner Pool Has Been GREEN for a Month

The basics of swimming pool maintenance.
New swimming pool owner's questions.
Help getting started with daily pool care.
chem geek
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Postby chem geek » Mon 06 Aug, 2007 18:12

Malena,

I hope your pool is continuing to clear. As for the pool not holding chlorine until you used the phosphate remover, the reason is that your pool had algae growth, even when it may not have been visible early on, and that consumes a LOT of chlorine. As your CYA level rose due to use of stabilized chlorine products (e.g. Trichlor, Dichlor) the algae was able to get ahead of the chlorine and form a full bloom.

Lowering the phosphates starved the algae which helped the chlorine get ahead of the algae growth, but higher levels of chlorine would have done the same thing. It's just that with a high CYA level you need a REALLY high chlorine level (over 40 ppm FC with over 100 ppm CYA) to shock the algae and that's just not practical and gets costly (and to prevent algae you would have needed an FC target of over 12 ppm). That's why the advice of partial drain/refill was given since lowering the CYA let's you use a lower chlorine level to kill the algae quickly.

There are many users with high phosphate levels, even 3000 ppb (3 ppm), that maintain their pools with chlorine alone and do not get algae. There are a very small handful (three) out of all pool forums I've monitored that have reported high phosphates and said the chlorine would not get rid of the algae (and in some cases I'm not sure the chlorine shock levels were maintained to get rid of the algae) so usually using the expensive phosphate remover is the last resort, not the first thing to do.

Richard


bamamelena

Postby bamamelena » Wed 08 Aug, 2007 18:27

Wow.. I could have SWORN I posted the other day!!! Hmm....

Anyway, I've continued to monitor my pool, putting in almost 15 gallons of bleach since last week. I've been backwashing every day, and even vacuumed this weekend, in the shallow end.

My DH said that it looks better today that it looked this weekend, and that's even better!!

We can actually see the drain, and all the leaves and junk around it. :(

I am going to hook the Polaris up tomorrow, but I think it's dead. The last time I hooked it up, when all the algae was still present, it wouldn't move at all. We had it looked at a few months ago, and they said nothing was wrong.

If it's still not working, I'll take it to my 'new' pool store, and have them look it over for $15, then decide if it's worth fixing.

I'm holding chlorine like never before!! I didn't have to put any in from Friday until Monday.

I forgot that I have one of those tester kits that come with the red and yellow drops. You fill the tester up with pool water, and then put coordinating drops in it, and it will tell you your numbers, as well, if you know how to look at it!

Anyway, my pool is clearing, and looks so much better!! It's still cloudy, but I can deal with clouds.

Thanks again for all your help, support and advice. I will be back!! This is the best pool forum I've found.

I hope everyone has a great day!!

~Melena
Backglass
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Postby Backglass » Wed 08 Aug, 2007 22:03

bamamelena wrote:We can actually see the drain, and all the leaves and junk around it.


<WHOOP! WHOOP! Warning! Warning!>

And there you have it. THAT is why you couldn't hold chlorine...not phosphates. You have had a pile of "leaves and junk" (ie: organic matter) EATING YOUR CHLORINE. It's no wonder you were having such problems. Your were basically trying to dissolve a pile of leaves with chlorine alone. Imagine if every kid in your pool "peed" a pile of leaves. You would never be able to keep it clear!

Get a leaf net. Remove ALL the "leaves & junk". You will see a very rapid improvement in your pool clarity.
===============================
I'm no expert...just a long time pool owner. The real experts are at www . troublefreepool . com

Download Bleachcalc free at troublefreepool . com /files/BleachCalc262.exe and start saving money on chemicals.
bamamelena

Postby bamamelena » Thu 09 Aug, 2007 17:35

I have a leaf net, and have been skimming my pool every day.

There's not that much around it, just a few leaves that the skimmer didn't get. It's not a great big pile. I couldn't see the bottom of the pool before now, so I couldn't see what was down there.

Went out just now and looked...it's actually pretty clear. Got some dead algae on the bottom floor, and will have to vac, but going to wait until it cools down some. It's 110 again today!

Still holding chlorine!
pool tech

green pools

Postby pool tech » Sat 11 Aug, 2007 01:21

Everybody has a right to their own opinion but I service 100 pools a week including commercial pools. You do the math on how many services that is per year. I am in Sacramento so we have hot weather. All my pools are crystal clear. 99% of the time the only chemicals they require are 2-3 chlorine tablets per week. And if by some chance one of them turns green, it's usually due to phosphates and with my method the pool is usually clear again in 1-2 days. I have owners of other pool companies that call me daily to ask me how to get their pool clear. But what would i know I've only serviced 30,000+ pools and can repair or install about any piece of equiptment out there.
chem geek
Pool Industry Leader
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Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

Postby chem geek » Sat 11 Aug, 2007 12:55

pool tech,

I'm not saying that using a phosphate remover won't prevent algae. I'm saying that phosphate removers are expensive and unnecessary since chlorine alone will prevent algae if maintained at the appropriate level relative to the CYA level. A maintenance dose of PolyQuat 60 algaecide will also prevent algae and not have one worry about CYA level. So there are different options and methods. It's not "I'm right and you're wrong" -- nor is it "everyone is entitled to their own opinion" with regard to using phosphates.

Since some of your high CYA pools with the chlorine levels you are maintaining (that I suspect is less than 6 ppm FC) get algae, then that is consistent with what I have been saying and the chemistry behind chlorine and CYA. Phosphates are algae food -- they do not "create" algae so clearly the amount of chlorine in the pool was insufficient to kill the algae and even at "ideal" algae food levels of phosphates, nitrates and carbonates, there is a limit to their growth rate (roughly 3 hours per generation) so if chlorine can kill the algae faster than it reproduces, the algae will not grow. You said that was not true, but that is wrong -- chlorine will kill algae even under ideal algae growth conditions and in fact has been done over and over again in many labs as well as hundreds of residential pools as reported on multiple pool forums. Your recommendation of shocking to 10 ppm FC will not kill an algae bloom if there's plenty of algae food -- you are right about that -- but it's because to quickly kill algae in a bloom you need 40% of the CYA level which at 80 ppm CYA would be 32 ppm FC and to kill an algae bloom slowly you would need 20% of the CYA level which would be 16 ppm FC. So it's no surprise that 10 ppm FC doesn't work for some 80 ppm CYA pools -- it's way too slow and the large amounts of algae use up the chlorine much too quickly.

In your pools in sunny and hot Sacramento, you want to run them with higher CYA levels because you don't want to lose the chlorine to sunlight as quickly. 60-80 ppm CYA is also the recommended range for most saltwater chlorine generator (SWG) pools for the same reason -- so they can run at a lower rate since there will be less chlorine loss during the day due to sunlight (UV rays). So the plus side at the higher CYA levels is that with lower chlorine loss you use less tabs and have less risk of running out of chlorine. But the downside is that unless the Free Chlorine level is kept high OR phosphates are kept low OR a weekly algaecide is used, then the risk of getting algae is higher. And constantly using Trichlor tabs will have the CYA keep rising unless you do significant backwashing or other dilution. I'm not saying that someone HAS to lower the CYA -- I always say that they can maintain a higher FC level instead as another option. However, killing an existing algae bloom at high CYA levels IS hard as it takes a LOT of chlorine -- so at that point the expensive phosphate remover starts to look like a better option (algaecide with copper will also work, but then you've got copper in the pool to deal with).

By the way, phosphates typically come from fertilized soil or blown-in fertilizer since that contains phosphates and nitrates -- that is, plant food. Have you ever had a pool you treated with phosphate remover develop algae again at some later point in time? If so, then this means that such a pool is getting regular additions of phosphates so will require periodic phosphate remover. Though that can certainly be done, one could instead just maintain a higher chlorine level appropriate for the CYA level (or can use a weekly PolyQuat 60 algaecide is mentioned earlier).

At very high CYA levels, above 150 ppm, there are potential problems with corroding plaster as seen in this link .

So with your 80 ppm CYA pools, what is the minimum Free Chlorine (FC) level that you maintain? I'm curious as it will give me an idea of typical low FC levels that can be maintained in many pools, but not those with higher phosphates that you then treat on a case-by-case basis. To not need the phosphate removers at all, the FC level would need to be a minimum of around 6.0 ppm (7.5% of the CYA level) to not get algae in even high phosphate pools and my normal recommendation for a "target" FC level is 11.5% of the CYA level (so 9.2 ppm with 80 ppm CYA) since that gives some buffer for error as people often have a hard time consistently making sure they never drop below the "minimum". These levels weren't made up by me -- they came from Ben Powell at The Pool Forum in his original chlorine/CYA table (see this link ) and he, too, serviced large commercial pools. I refined the data based on the actual chemistry involved. So his experience and yours are not different -- you just chose a different solution than he did, but that doesn't make one right and the other wrong.

Richard
pool tech

green pools

Postby pool tech » Sat 11 Aug, 2007 15:54

I keep my cl2 levels between 3-5 ppm TA 100-120 PH 7.4 CYA 80-100
CH 240-400 on all my pools. If I am maintaining these pools all year round 1 or 2 will start to turn green on me during the summer. That is a very low percentage considering I maintain 100 pools. When the pool starts to turn I check all my chems to make sure their in range and I then check for phosphates. If the phosphate levels are low I just shock the pool with 2-4 gallons of chlorine and it takes care of the problem. If the phosphates are high the chlorine shock will not work unless I remove the phosphates from the pool. Either way the pool ends up crystal clear for the rest of the year and it generally takes only 2 days to clear up. This method works for me without failure here in sacramento. You may have it different where your at.
chem geek
Pool Industry Leader
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Posts: 2382
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

Postby chem geek » Sat 11 Aug, 2007 21:10

pool tech,

The 3-5 ppm FC with 80-100 ppm CYA is right on the edge of where algae will develop IF it has enough food to reproduce faster than the chlorine can kill it (the 3 ppm FC with 100 ppm CYA is the most susceptible). So you are fortunate that most of your pools don't have lots of phosphates or otherwise encourage fast algae growth. Keep in mind that at lower amounts of algae, the pool won't be green, but will look cloudy or just "dull" where the main drain isn't crystal clear as if looking through a glass of water, but you reported the water looking crystal clear so that's good. Also, if there is this nascent algae with dull water in the pool, then chlorine consumption is higher so shocking and then maintaining higher FC levels can actually reduce chlorine consumption. This most often shows up in SWG pools where they are running just a little too low in FC and then can't set the SWG high enough to keep the pool clear.

So thanks for the info as it means that the recommendations are conservative, at least for green algae. Quite a few residential pool users with 3 ppm FC and 100 ppm CYA report getting green algae. Now, there have been reports of yellow/mustard algae, usually around this time of year (August) and we've found (through experiments with a few pool users on pool forums) that this algae requires higher levels of chlorine to keep away -- around 15% of the CYA level or about twice the minimum amount needed for green algae. So that is another situation where the phosphate removal application is an option if one doesn't want to maintain higher FC levels as it should take care of mustard/yellow algae as well. I'm less clear as to whether PolyQuat 60 is as effective at preventing mustard/yellow algae -- Buckman Labs says its effective, but I haven't seen real pools with that combo so don't know for sure.

I'm not a pool service person -- I'm an individual pool owner. I just collect the info from a variety of pool forums and work out the chemistry of pool water. Along with some other pool forum users, we've worked out some things that are counter to what the pool industry normally believes. Such as how to lower TA (through aeration at low pH rather than the "slug" method of acid addition) and the real source of rising pH in SWG pools (it's the hydrogen gas bubbles from the SWG that pulls carbon dioxide out of the water) and how to lower the tendency of the pH to rise (reduce aeration, if possible, and lower the TA -- counter-intuitive), bleach and chlorinating liquid are actually pH neutral when accounting for chlorine usage (which is acidic), etc.

By the way, what do you do to prevent CYA from continuing to increase throughout the season? Do you backwash more or do explicit dilution? For every 1 ppm FC you add from Trichlor pucks/tabs, this also adds 0.6 ppm to CYA so over a season it's easy to add at least 100 ppm or more to CYA (just 1 ppm FC per day over 6 months would add 108 ppm to CYA).

Richard
Backglass
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Postby Backglass » Sun 12 Aug, 2007 10:04

pool tech,

Doctors and Surgeons continue to learn new techniques and never stop training. They used to fillet you open to remove an appendix...now they do it laproscopically. Does the older way work just fine? Sure! Is it the most efficient, cheapest and fastest? Probably not.

You maintain over 100 pools. I maintain one. You have one or two turn green in a season. Mine has yet to turn green. If you want to spout numbers as proof of knowledge, my ratio's better. :P

I have no doubt you know a lot about pool mechanics, but you should take some time to fully investigate the latest techniques of water chemistry. It will make you a better pool surgeon! :lol:

"Open your mind Luke!" - Obi Wan Kenobi
===============================

I'm no expert...just a long time pool owner. The real experts are at www . troublefreepool . com



Download Bleachcalc free at troublefreepool . com /files/BleachCalc262.exe and start saving money on chemicals.
chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2382
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

Postby chem geek » Sun 12 Aug, 2007 13:13

I appreciate and want pool tech's feedback and experiences. As I said, the recommended ranges for chlorine levels came initially from a person who serviced many large commercial pools so experience (which is analogous to experiments) is where the core information comes from and is extremely useful. My contribution is mostly matching that (and reports from hundreds of pool users on multiple forums) up against chemical theory to come up with recommendations that are consistent with both, when possible. The 3-5 ppm in pool tech's pools is probably maintained better than what most residential pool users do and perhaps is part of the reason for the less frequent green algae in his pools.

Even the Pinellas County pool study in Florida (see this link for links to it and my analysis) had only 4 pools with green algae out of 486 pools and none of the 49 pools with ZERO chlorine had any green algae even though (as expected) most ( 28 ) were bacteriologically unsafe. This, however, is not the experience of most residential pool users. Most pools will develop green algae if left untreated without chlorine. So this is why I thought something else was going on such as use of an algaecide (or phosphate remover) in the Pinellas pools. Also note that in the Pinellas study there were 5 pools with over 5 ppm FC and a total of 9 pools with over 4 ppm FC that were bacteriologically unsafe and some of these pools had zero CYA. So clearly there are other substances making chlorine ineffective, but nobody looked into that.

So I really appreciate and value pool tech's experience and would still like to know what he's doing to keep the CYA level from rising since that is the primary problem when using Trichlor as the sole source of chlorine in pools.

Richard

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