Algae Growing In The Pool...

[zappalot]

we have a pool in the backyard of our condo in about 20 meter above the ground.

A few weeks ago our management decided that our maintenance staff can handle the maintenance of the pool easily, the result is that:

And as I the farang knows everything better they told me I can take care the pool or order a company i know, they would pay.

They have a filter system, but the chlorine is added manually everyday in the morning. They never measure the chlorine, the PH-value or anything else, just throwing in some chlorine.

Of course the result must be like that shown above sooner or later, it came sooner than later...

So as I dont know nothing about all these things away from what i read here: can someone recommend someone who can bring the pool back to clear water AND then teach our maintenance staff how to take care the pool properly?

Any help is appreciated...

Thank you very much...

[seabear]

First you make a super chlorination to kill the bugs.

Then you add Aluminium sulphate as a flocculant.

And then you add Copper sulfate as an algae killer.

(Google is your friend)

My pool has about 450 m³ of water. ph and chlor is measured daily, and the pool is vacuum cleaned daily.

For a smaller pool I would consider a roboter.

[tollgate]

zappalot - what area are you in?

seabear - 450 cu m - that's one big pool.

[zappalot]

on bangna-trad road

they promised us that a professional (whatsoever that mean in thailand) company will come today and fix the problem.

they didnt want me to try, of course in the mean time (seabear was right of course, use google...) i found some more information...

lets see...

[Naam]

zappalot - what area are you in?

seabear - 450 cu m - that's one big pool.

or a calculation mistake

[zappalot]

stupid management - just checked the pool.

they have done nothing - the only thing they do is using the vacuum cleaner for the pool now every morning. but as long as they don't kill the algae this is useless. they don't get that just cleaning will not resolve the problem.

they are so stupid - we printed out a detailed description how to solve the problem in thai language. when i was in the office i wanted to see the paper - they never even had a glance at it, it was under a thick layer of other papers and he asked me if this is a description of how to resolve the problem...

[khunPer]

Astral Pool (brand name) makes a multi action ball wirh chlorine, flucculant (aluminium) and algicide (copper). 1 ball pr. 10m3 water weekly, fx. in the skimmer(s). Quantum may be adjusted after your need. I use it and it's easy to use. You may need to adjust/add chlorine sometimes, if water gets unclear. You can use an extra algicide, if/when algae problems arise. Remeber to vacuum to pool and bachwash filter(s).

See more at www.astralpool.co.th

[tollgate]

I would avoid adding copper to a pool. My pool buider added copper to my pool just after completion and it caused no end of problems with copper deposits in the grout. Thankfully the copper is mostly gone now. It's also copper in the water that turns blonde hair green, not chlorine. The best way to avoid algae is to make sure your pool is properly chlorinated.

[jaideeguy]

Pardon me for hijacking this thread, but seems that we both have similar problems. I am experiencing the worst algae attack I've had in 7 yrs and have super shocked my pool, then added floculant [PAC] twice in this month and the algae keeps returning. Filtering 6-7 hrs a day for a 84 cu mtr pool and still have algae. Today, I just tripled the chlorine and added floc again. I am reluctant to go with the copper, but may have to if this last effort doesn't work. Just wondering how long does it take for the copper to dissipate??

BTW, my source water is probably the cause of it......a lake in the ricefields near us, but I have used it before and have always been able to clear it. Could it be a chlorine resistant strain of algae??

[AllanB]

Pardon me for hijacking this thread, but seems that we both have similar problems. I am experiencing the worst algae attack I've had in 7 yrs and have super shocked my pool, then added floculant [PAC] twice in this month and the algae keeps returning. Filtering 6-7 hrs a day for a 84 cu mtr pool and still have algae. Today, I just tripled the chlorine and added floc again. I am reluctant to go with the copper, but may have to if this last effort doesn't work. Just wondering how long does it take for the copper to dissipate??

BTW, my source water is probably the cause of it......a lake in the ricefields near us, but I have used it before and have always been able to clear it. Could it be a chlorine resistant strain of algae??

When you say super shocking what ppm level are you referring to?

I think I am right in saying metals stay in the water unless you filter them out. Our water supply has a lot of iron in it so I filter my top up water through a 1 micron filter, with some level of success. Without analysing the dirty filter content, I suspect the water has algae in it too.

I personally wouldn't put any metals into my pool, preferring filtration instead, many pool companies are now using 5 micron bag filters, in place of the 50 or 15 micron ones of the past. This is presumably to handle live algae, where, due to the local climatic conditions, the chlorine just isn't working.

It would be very helpful if someone would carry out an independent study into domestic pool water treatment, especially in tropical climates where events are more dramatic and remedies less effective. Though we may have to get Wikileaks to publish it.

[jaideeguy]

Pardon me for hijacking this thread, but seems that we both have similar problems. I am experiencing the worst algae attack I've had in 7 yrs and have super shocked my pool, then added floculant [PAC] twice in this month and the algae keeps returning. Filtering 6-7 hrs a day for a 84 cu mtr pool and still have algae. Today, I just tripled the chlorine and added floc again. I am reluctant to go with the copper, but may have to if this last effort doesn't work. Just wondering how long does it take for the copper to dissipate??

BTW, my source water is probably the cause of it......a lake in the ricefields near us, but I have used it before and have always been able to clear it. Could it be a chlorine resistant strain of algae??

When you say super shocking what ppm level are you referring to?

I think I am right in saying metals stay in the water unless you filter them out. Our water supply has a lot of iron in it so I filter my top up water through a 1 micron filter, with some level of success. Without analysing the dirty filter content, I suspect the water has algae in it too.

I personally wouldn't put any metals into my pool, preferring filtration instead, many pool companies are now using 5 micron bag filters, in place of the 50 or 15 micron ones of the past. This is presumably to handle live algae, where, due to the local climatic conditions, the chlorine just isn't working.

It would be very helpful if someone would carry out an independent study into domestic pool water treatment, especially in tropical climates where events are more dramatic and remedies less effective. Though we may have to get Wikileaks to publish it.

I can't say how many ppm chlorine I'm using, as I use a granular trichlor 90% slow release, but I'm more than doubling the amount and when I test, it's off the scale......very bright yellow.

And yes, I do agree with you and am reluctant to use copper.....so are there any other algaecide alternatives that are less harmful??

[AllanB]

Algaecides are all bad news, they cause skin irritation and stain the pool. The chlorine ppm is the important figure, so you need to know how much water you have, use the metric system it makes things very much easier.

I have an 8m x 4m x 1.3m pool, so 41 m3, call it 40 m3, one shock 500g (25 tablets) = 12.5ppm x 90% if you like....

First of all shock, is just that fast acting, so slow acting powder is unsuitable and if you are normally running 2ppm, merely doubling that is not enough. That said, you mentioned it went of the scale and the scale normally goes up to 10ppm, which implies that you are normally running at 5-6ppm, which is quite high for a domestic pool. If you are using a slow acting powder at that continuous high level your ph will either be very low, or you are using a lot of ph+. I think I have that right,...

My water is pretty much back to normal, after a bit of hard work, but only shock chlorine used. I emptied around 30 (1 micron) bags of white slime from the bottom and about 20 bagfuls of light green slime from the 5 micron bag in my skimmer. Tomorrow morning should see the all-clear.

Funny stuff algae, it is everywhere just waiting for half suitable conditions to germinate, we have 3 other pools in my village and they are all permanently green. I left the pump off for a few days, ran it only a little for a couple of days and have spent 4 days clearing up the mess, perhaps I should have drained the pool. Trouble is my tap water is full of crap too.

[SantiSuk]

I must have been very lucky. I've never used quick-acting chlorine for shocking my pool, yet the dreaded green attacks (usually in the form of green tinging to parts of the pool that get less direct sunlight or a green tinge to the water that appears overnight) have always gone away with:

- brushing the pool sides (with an 18" wide soft nylon brush and snorkelling gear it's not as onerous a job as it sounds - I look at it as part of my exercise programme!)

- running the pump for 50% more for a day

- applying extra quantities of the Trichlor 90% powder to achieve roughly 12ppm.

I get attacks every couple of months, mostly because I go back to the UK for 2 weeks and pool boy (my BIL) is a bit hit and miss with his cleaning and dosing routines.

I do get thick green algae in the concrete return channels (where the water goes to return to the reserve tank in an infinity pool). Its a hot job for half a day every 6 months removing the gunk, hoovering out the reserve tank to waste and backwashing the filter. I'm thinking of tiling the bottom of the channels to reduce the stickability of the algae. Does anyone else with an infinity pool have either concrete or tiled return channels and what has been your experience of algae in them?

I'm surprised given that the channels are a breeding grounmd that I have fairly limited difficulties with the pool itself. Fingers crossed.

I'm not using cheap powder because I don't believe in fast-acting (I note that WikiHow confirms that's what you need). Neither am I being a cheap Charlie - the one time I went up to Bangkok to buy rapid acting shock chlorine I got nowhere with sourcing it. One Thai pool shop owner told me not to be a silly farang and just use high doses of the regular stuff and other shops just sold mini and maxi pucks without knowing whether they would qualify as fast-acting shock chlorine or not. I wrote a thread about a year ago I recall.

So, where do you guys get your shock chlorine from if it's in the Bangkok area?

[AllanB]

I must have been very lucky. I've never used quick-acting chlorine for shocking my pool, yet the dreaded green attacks (usually in the form of green tinging to parts of the pool that get less direct sunlight or a green tinge to the water that appears overnight) have always gone away with:

- brushing the pool sides (with an 18" wide soft nylon brush and snorkelling gear it's not as onerous a job as it sounds - I look at it as part of my exercise programme!)

- running the pump for 50% more for a day

- applying extra quantities of the Trichlor 90% powder to achieve roughly 12ppm.

I get attacks every couple of months, mostly because I go back to the UK for 2 weeks and pool boy (my BIL) is a bit hit and miss with his cleaning and dosing routines.

I do get thick green algae in the concrete return channels (where the water goes to return to the reserve tank in an infinity pool). Its a hot job for half a day every 6 months removing the gunk, hoovering out the reserve tank to waste and backwashing the filter. I'm thinking of tiling the bottom of the channels to reduce the stickability of the algae. Does anyone else with an infinity pool have either concrete or tiled return channels and what has been your experience of algae in them?

I'm surprised given that the channels are a breeding grounmd that I have fairly limited difficulties with the pool itself. Fingers crossed.

I'm not using cheap powder because I don't believe in fast-acting (I note that WikiHow confirms that's what you need). Neither am I being a cheap Charlie - the one time I went up to Bangkok to buy rapid acting shock chlorine I got nowhere with sourcing it. One Thai pool shop owner told me not to be a silly farang and just use high doses of the regular stuff and other shops just sold mini and maxi pucks without knowing whether they would qualify as fast-acting shock chlorine or not. I wrote a thread about a year ago I recall.

So, where do you guys get your shock chlorine from if it's in the Bangkok area?

So your normal chlorine level is about 6ppm, that is quite high, I think, though I am still experimenting with levels and about 2ppm works for me, but I have a bag filter, no tank and I have a roof, so cooler water. Basically you have a chlorine rich clean pool, but the rest of the system, filter, tank and channels are all dirty, this is why problems manifest themselves quickly when the pool's chlorine level drop, when you are away.

With regards to the algae in your return channels, have you thought about using plastic piping, cut down it's length to form two lengths of guttering the PVC channels wouldn't trap algae and any it does collect would be easy to clean.

Have you also considered dosing your reserve tank after cleaning? I would use household bleach for that..

[Chaichara]

" One Thai pool shop owner told me not to be a silly farang and just use high doses of the regular stuff and other shops just sold mini and maxi pucks without knowing whether they would qualify as fast-acting shock chlorine or not. "

I'm not surprised. Many pool shop owners/constructors appear to be former general builders who have launched themselves into the lucrative pool business without any real knowledge of pool chemistry at all. Aluminium sulphate is one of the best and fastest acting clarifiers, but like many pool chemicals, it is often packed and marketed under proprietary brands for pools and sold at exhorbitant prices.

Genuine pool algicides and clarifiers such as those manufactured by Applied Biochemicals are very good especially Balck Algitrine which works well. After treating, algae problems don't stop, regular preventitive dosing will be necessary.

Chlorine will prevent algae growth to some extent, copper sulphate is a well proven santisiser and some pool santitation systems use a sacrificial copper anode. There are plenty of liquid algicides on the maket for pools.

That said, in severe cases of murky pools, because chemicals are expensive, it can sometimes be more economical to change the water and start over. Probably not too practical for a 400 m3 pool, or where water has to be trucked in by tanker, though.

[SantiSuk]

Not sure how you deduce that I'm on 6ppm AllanB. Much less than that. Apart from when I'm shocking I wait for the free chlorine level to drop to below 1.0 before dosing to achieve around 2. Tends to mean I'm dosing every 2 days in the hot season and 3-4 otherwise. I'm only doing that because my very first basic 2 tubes test kit indicated that 0.6 to 1.5 as the ideal range.

Nice idea about the PVC pipe - I might try that out on one side of the pool: there is a risk it would restrict the volume that can be shipped back to the reserve tank in rainy weather, resulting in overflow all round the pool

[tollgate]

SantiSuk - do you know what your cya level is? You cannot really calculate how much chlorine you need to add to get to shock level unless you know.

[Chaichara]

To do that he would probably need a cyanuric acid test kit, or have a water analysis done.

[jbrain]

SantiSuk - do you know what your cya level is? You cannot really calculate how much chlorine you need to add to get to shock level unless you know.

To calculate the amount of chlorine needed to shock a pool, you need to know the combined chlorine level. The combined chlorine level is calculated by deducting the free chlorine level from the total chlorine level. Nothing to do with cyanuric acid levels.

You shock the pool by adding free chlorine 10 times the amount of the combined chlorine readings

[tollgate]

To do that he would probably need a cyanuric acid test kit, or have a water analysis done.

Yes, he would need a test kit.

SantiSuk - do you know what your cya level is? You cannot really calculate how much chlorine you need to add to get to shock level unless you know.

To calculate the amount of chlorine needed to shock a pool, you need to know the combined chlorine level. The combined chlorine level is calculated by deducting the free chlorine level from the total chlorine level. Nothing to do with cyanuric acid levels.

You shock the pool by adding free chlorine 10 times the amount of the combined chlorine readings

I disagree. The amount of chlorine required has everything to do with cya level.

[AllanB]

Not sure how you deduce that I'm on 6ppm AllanB. Much less than that. Apart from when I'm shocking I wait for the free chlorine level to drop to below 1.0 before dosing to achieve around 2. Tends to mean I'm dosing every 2 days in the hot season and 3-4 otherwise. I'm only doing that because my very first basic 2 tubes test kit indicated that 0.6 to 1.5 as the ideal range.

Nice idea about the PVC pipe - I might try that out on one side of the pool: there is a risk it would restrict the volume that can be shipped back to the reserve tank in rainy weather, resulting in overflow all round the pool

Sorry mate, clicked on the wrong posting, it was Jaideeguy who said.."I can't say how many ppm chlorine I'm using, as I use a granular trichlor 90% slow release, but I'm more than doubling the amount and when I test, it's off the scale...... " Off the scale is about 12ppm, so half is 6ppm.

​Funny thing algae, a friend of mine has had a problem with his pump, not had it running for two weeks, did a test today, no sign of chlorine very low ph and his water is as clear as a bell, we will see what happens tomorrow when we start adding stuff.

[SantiSuk]

Funny how pool people always have such widely different views on pool chemicals and then spout them as gospel. Not attacking any particular individulas on this thread - its a recurring theme in the SP forum.

Yes I do measure my CyA level (not very regularly, about monthly, as it varies so little).

Since there seem to be such differing views about the appropriate CyA levels (many seem to argue that you should keep it high as long as it doesn't go over 80, but I've seen proper research that says anything over 20% is throwing money away) I'm not sure I would trust any tables that might base a chlorine shock level on the CyA level, but would be moderately interested to read the source data and conversion rates.

I thought that the object of shocking was to bring down the combined chlorine level down to a very low level, so I can see why conversion based on the prior combined chlorine level might make sense. My combined chlorine level seems to very widely depending on the level of Total Chlorine though, so I would need to know the level at which combined chlorine should be measured.

Actually the Bangkok Thai pool store owner's guidance (he also claimed to be the largest importer of chlorine in Thailand and had a big warehouse to back up that claim btw) to "add enough to get to 10ppm, normal powder is fine for that" seems to work for me. Maybe I'm putting too much in but at 100 baht a kg for Japanese tricholor powder I'm not too fussed. The 5kg tub of fast acting chlorine that I did end up buying in a Bangkok pool store is very natty - little pucks that dissolve super-fast - but I reckon there's only enough in there to do about 4 shocks for 1,600 baht!

Unless someone can come up with an authoritative source as to how to calculate shock requirements (I mean one with research behind it) I think I'll leave all you amateur pool chemists to argue amongst yourselves

[jbrain]

Funny how pool people always have such widely different views on pool chemicals and then spout them as gospel. Not attacking any particular individulas on this thread - its a recurring theme in the SP forum.

Yes I do measure my CyA level (not very regularly, about monthly, as it varies so little).

Since there seem to be such differing views about the appropriate CyA levels (many seem to argue that you should keep it high as long as it doesn't go over 80, but I've seen proper research that says anything over 20% is throwing money away) I'm not sure I would trust any tables that might base a chlorine shock level on the CyA level, but would be moderately interested to read the source data and conversion rates.

I thought that the object of shocking was to bring down the combined chlorine level down to a very low level, so I can see why conversion based on the prior combined chlorine level might make sense. My combined chlorine level seems to very widely depending on the level of Total Chlorine though, so I would need to know the level at which combined chlorine should be measured.

Actually the Bangkok Thai pool store owner's guidance (he also claimed to be the largest importer of chlorine in Thailand and had a big warehouse to back up that claim btw) to "add enough to get to 10ppm, normal powder is fine for that" seems to work for me. Maybe I'm putting too much in but at 100 baht a kg for Japanese tricholor powder I'm not too fussed. The 5kg tub of fast acting chlorine that I did end up buying in a Bangkok pool store is very natty - little pucks that dissolve super-fast - but I reckon there's only enough in there to do about 4 shocks for 1,600 baht!

Unless someone can come up with an authoritative source as to how to calculate shock requirements (I mean one with research behind it) I think I'll leave all you amateur pool chemists to argue amongst yourselves

This might be helpful to you.

http://www.underwaterstuff.com/definitions.htm

Shocking isn't something you do regulary, you do it when neccessary, and need to have the levels right otherwise you make things worse.

The formula for shocking is not 10 ppm but 10 times the level of combined chlorine.

To measure it you need a Taylor testkit or Aquachek or Lamotte teststrips which can test for Total chlorine and Free chlorine.By deducting the latter from the first one, you become the combined chlorine.

Aquachek 5 in 1 strips can be ordered from Ebay at affordable prices, I just ordered 7 in 1 Aquachek at 27$ for 100 strips.

Chlorine can be purchased at different purity levels. here in Pattaya they sell 90% chlorine powder/granular at 620 Baht for 5 Kg or 1750 Baht for 25 Kg.

I think granular is recommended for algae treatment as they sink to the bottom so will be in direct contact with the algae.

Edit to add another source : http://www.tps.com.au/pools/shock.htm

[jbrain]

Yes I do measure my CyA level (not very regularly, about monthly, as it varies so little).

Since there seem to be such differing views about the appropriate CyA levels (many seem to argue that you should keep it high as long as it doesn't go over 80, but I've seen proper research that says anything over 20% is throwing money away) I'm not sure I would trust any tables that might base a chlorine shock level on the CyA level, but would be moderately interested to read the source data and conversion rates.

Cyanuric acid level isn't directly related to sanity of a pool. Cyanuric acid is a stabilizer that slows down the process of the Chlorine to be degraded by the sun.

The less sun your pool is subject to, the lower the CyA levels have to be.Indoor pools for example will have next to none CyA added.

CyA also doesn't vaporize, so if you don't release any water of your pool the level will not change. Keep in mind that those chlorine tablets contain CyA and you built up your levels that way,so at one point you may have to release water to lower your CyA levels since anything above 100 ppm is considered a health risk.

[SantiSuk]

I meant something a bit more than another pool products web-site when I said authoritative, JPB. I suspect I could find another pool shop's guidance that gave different guidance about shocking. I would not let my pool get to a combined chlorine level of 1ppm (used in the example in the website quoted), because some other guidance I read elsewhere on the internet said that you should shock if your combined chlorine level reaches 0.5ppm. But who knows whether my source was any good! See - pool chemistry seems to be all about opinion and everybody has one, based on what they read last. Ask people on this thread what is the best pH level to maintain and I'll bet you'll get different answers in the range 7.1 to 7.6.

I did know all the stuff in your posts Btw, but perhaps you were putting that all out to help newbies.

1,750 baht for 25kg of chlorine powder - that's cheap and will probably be Chinese stuff. Japanese costs a bit more (the guy who imports both for Thailand told me that and gave his relative retail prices as about 3,500 for Chinese and 5,000 for Japanese (50kg tubs). But hey - who knows which is best. Without proper academically researched results, let's not get to precious about pool chemistry!

Again nothing personal guys - it's a rant against the lack of truly authoritative guidance in the industry not any individual!

[jbrain]

I meant something a bit more than another pool products web-site when I said authoritative, JPB. I suspect I could find another pool shop's guidance that gave different guidance about shocking. I would not let my pool get to a combined chlorine level of 1ppm (used in the example in the website quoted), because some other guidance I read elsewhere on the internet said that you should shock if your combined chlorine level reaches 0.5ppm. But who knows whether my source was any good! See - pool chemistry seems to be all about opinion and everybody has one, based on what they read last. Ask people on this thread what is the best pH level to maintain and I'll bet you'll get different answers in the range 7.1 to 7.6.

I did know all the stuff in your posts Btw, but perhaps you were putting that all out to help newbies.

1,750 baht for 25kg of chlorine powder - that's cheap and will probably be Chinese stuff. Japanese costs a bit more (the guy who imports both for Thailand told me that and gave his relative retail prices as about 3,500 for Chinese and 5,000 for Japanese (50kg tubs). But hey - who knows which is best. Without proper academically researched results, let's not get to precious about pool chemistry!

Again nothing personal guys - it's a rant against the lack of truly authoritative guidance in the industry not any individual!

My mistake.

I thought you were looking for some information, but it seems that you are the guy who knows everything better than anyone else.

I am amazed that you with your basic 2 tube test kit are able to measure free chlorine or combined chlorine. Such a kit, which you say you use in post #16 can only measure total chlorine, which is in fact useless. The total chlorine you measure can be ALL combined chlorine.

As I said already, reaching just below breakpoint when shocking only makes things worse.So just guessing how much chlorine your pool needs is playing with fire.

It also surprises me that such a knowledgeable guy doesn't know that there is no such thing like an ideal PH level, but that between 7.2 and 7.6 is recommended.

So if the guidance regarding how to shock a pool isn't good enough if it is provided by a pool shop, I don't see how they can benefit from giving wrong information in this case, then who you expect to know.

Maybe you could ask your wife, or look in the mirror while you're giving yourself advice. You will for sure hear what you want to hear.

But anyway, I'm sure you are very professional and are doing something right if you have algae attacks every few months.

[Naam]

there is no such thing like an ideal PH level, but that between 7.2 and 7.6 is recommended

some people give a "flying eff" about recommendations and run their pools since decades with a pH of 6.5-6.8 which is closer (and therefore healthier) to the average skin pH of a human being (5.5).

the often quoted value 7.2 is based on the pH of the eye liquid and/or optimal chemical balancing. compare surface area of exposed eyes with total surface area of body and start thinking

[SantiSuk]

I meant something a bit more than another pool products web-site when I said authoritative, JPB. I suspect I could find another pool shop's guidance that gave different guidance about shocking. I would not let my pool get to a combined chlorine level of 1ppm (used in the example in the website quoted), because some other guidance I read elsewhere on the internet said that you should shock if your combined chlorine level reaches 0.5ppm. But who knows whether my source was any good! See - pool chemistry seems to be all about opinion and everybody has one, based on what they read last. Ask people on this thread what is the best pH level to maintain and I'll bet you'll get different answers in the range 7.1 to 7.6.

I did know all the stuff in your posts Btw, but perhaps you were putting that all out to help newbies.

1,750 baht for 25kg of chlorine powder - that's cheap and will probably be Chinese stuff. Japanese costs a bit more (the guy who imports both for Thailand told me that and gave his relative retail prices as about 3,500 for Chinese and 5,000 for Japanese (50kg tubs). But hey - who knows which is best. Without proper academically researched results, let's not get to precious about pool chemistry!

Again nothing personal guys - it's a rant against the lack of truly authoritative guidance in the industry not any individual!

My mistake.

I thought you were looking for some information, but it seems that you are the guy who knows everything better than anyone else.

I am amazed that you with your basic 2 tube test kit are able to measure free chlorine or combined chlorine. Such a kit, which you say you use in post #16 can only measure total chlorine, which is in fact useless. The total chlorine you measure can be ALL combined chlorine.

As I said already, reaching just below breakpoint when shocking only makes things worse.So just guessing how much chlorine your pool needs is playing with fire.

It also surprises me that such a knowledgeable guy doesn't know that there is no such thing like an ideal PH level, but that between 7.2 and 7.6 is recommended.

So if the guidance regarding how to shock a pool isn't good enough if it is provided by a pool shop, I don't see how they can benefit from giving wrong information in this case, then who you expect to know.

Maybe you could ask your wife, or look in the mirror while you're giving yourself advice. You will for sure hear what you want to hear.

But anyway, I'm sure you are very professional and are doing something right if you have algae attacks every few months.

Sorry fellah!

Don't like being talked down to, like your incorrect assumption that I only use a two tube test kit (the ultimate put down to a pool owner? LOL). But - maybe I implied that somewhere.

Clearly you don't like being talked down to either. We are quits - let's move on :-)

[AllanB]

What chlorine levels do you guys run and do you increase the amount during the hot weather? A lot of people talk about 1 to 1.5ppm, but wonder if that is enough in the heat of the Thai summer. I am currently running at 3+ which seems to work and I can open my eyes underwater without a problem.

[Chaichara]

Ideal is 1.0 to 2.5. Boosting it beyond that will just waste chlorine. 'Shocking' is really intended to get the chlor up to those levels if it falls below it. Shocking is done simply with a faster releasing form of chlor, usually powder or granules, but it's often marketed more expensively as 'Shock' chlorine. It's actually cheaper (on the bulk market) than the slow-release tablets.

It may sometimes be worthwhile investing in decent Free Chlorine and Total Chlorine checkers. There are digital, photometric, and titration ones. They are not expensive and work out not much more than the standard 'blue box' test kit and buying multiple refils, and they are far more accurate. Supplement such water testing tools with a digital pH meter. Chuck the 'blue box ' out - they are pretty useless.

While chlor will combat algae to a certain extent, if infection persists, try using a proprietary algicide such as Algaetrine or Black Advance from Applied Biochemicals™. It's made in Thailand specially for pools so will not have the horrendous prices as imported branded stuff from the 'famous' pool brands. Use a high dose to start with, then continue with preventative dosing.