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Problems With A Salt Water Pool


mike1963

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Hi I have a salt water pool. It was all fine until about 10 days ago, where the water started looking less clear and less crystal blue. Upon cleaning I found the pool was unusually dirty, so gave it a good vacum.

As each day passed, the pool became more cloudy and started to turn green. Upon sweeping, I found clouds of fine dust were disturbed, so I assumed that the pool was more dirty than usual and this was the problem and vacumed more, hoping this would turn it back to normal.

I then used the backwash, but found the water from the backwashj to be clear.

Using test strips gave good readings on PH, FC, TA and CYA, yet with more cleaning it just got worse.

I assumed that there was a blockage or problem with the filter as the pool is dirty and the backwash is clear, and so I also thought the dirty water was not being flitered properly and the water circulating without proper or effective filtration.

The guy who built the pool and other "experts" who have attended have all said "green pool= algae, add chlorine", but I thought it was a silt/dust/dirt problem that was not being filtered properly.

They have now added chlorine and promise me it will be fine.

I was dead against them adding chlorine, they said try the chlorine first, if not, we'll investigate the pump/filter.

The SWC lights seems fine and I cleaned it out, although it was deposit free.

So, has anyone else ever experienced anything like this before? If so what did you do? If I am wrong (and I'm no expert and may well be) and it does need shcoking, or chlorine added, what type of chlorine or shock, readily available in Thailand can be used with a SW pool, as I was told it is not adviseable to shock a SW pool with chlorine.

If it is an algea problem, how could I prevent this happening again, as for 6 months since we started using it , everything was fine. Trying to go down the preventative road.

I currently use salt, muriatic acid to reduce ph, cya, and very occasionally Bicarb of Soda, is there anything else I should be using?

Finally, when facing problems like this and future ones, I would like to have a reliable, competent comapny or individual who I could call upon, who would be able to come to us direct, we live in Korat, and so far have not found anyone locally who fits that description. It would be nice to have such a person(s) who basically knows <deleted> they are talking about, and would attend.

Many thanks,

Mike.

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Algea is almost always a sign of low chlorine. However, there is a chemistry phenomenon that chlorine does not work efficiently in high pH water (above 8.0). Algae is sometimes seen in pools where there is a good chlorine level, but high pH. Knock the pH down with acid to release the killing power (oxidation) of chlorine. Keep alkaline in range to stabilize pH at 7.5.

You can shock a SW pool with either granular chlorine, or liquid chlorine. We like liquid chlorine, because its safe, easy, works quickly, then burns off quickly. However, if your pool pH is high, use the granules (90% strength); this is because this chlorine has a very low pH, and you will kill two birds with one stone (see first paragraph). You should try to learn about ORP, and begin measuring this instead of free chlorine. ORP takes into account the ph at the moment of testing sanitizer oxidation potential. All of our pools now have ORP sensors and pH sensors plumbed in.

Also, keep CYA in range, in 90% of all salt water pools, the owner is not familiar with CYA. Chlorine from a chlorinator is un-stabilized, and needs a supplemental stabilizer.

Cloudy water is almost always a filter problem. Don't backflush though, if pressure readings are normal. A little bit of dirt in the filter actually helps filtration. Check the pump impellor to make sure there is good cirulation rates (stagnant water goes green). There are no mysteries with pools, you will find the problem eventually.

Best,

Gil

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Mike

I thought your problem may have been linked to a hole in one of the vanes inside a DE filter which would allow water to pass through the filter without being filtered.

What about your water source? Have you added any water recently? City water, rain or well? Algae will only grow (bloom) if there is something in the water for it to feed on. Algae feeds on phosphates & nitrates. Water with a high concentration of either will allow algae to bloom. It will be difficult to control the algae as long as the phospahte/nitrates are present for it to feed on especially if either of these pollutants are present in large amounts. See if you can get your hands on a test kit to determine the level of phospahtes/nitrates in the water.

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Mike

I thought your problem may have been linked to a hole in one of the vanes inside a DE filter which would allow water to pass through the filter without being filtered.

What about your water source? Have you added any water recently? City water, rain or well? Algae will only grow (bloom) if there is something in the water for it to feed on. Algae feeds on phosphates & nitrates. Water with a high concentration of either will allow algae to bloom. It will be difficult to control the algae as long as the phospahte/nitrates are present for it to feed on especially if either of these pollutants are present in large amounts. See if you can get your hands on a test kit to determine the level of phospahtes/nitrates in the water.

I am not an expert on algae, but if I am not wrong, the majority of algae nourishment comes from sunlight. Photosynthesis is their preferred way of finding a good steak. Very small amounts of nitrates and phosphates might also be used, but I would surmise that algae does not form in dark places easily. When diagnosing pool problems, it pays us the most dividends to begin at the most common source of the problem. In 7 years of fixing pools, we have never used a phosphat kit (although I did have one at one time). It told me that there were phosphates in the water. I did a partial drain, re-filled, only to find just as many still there.

Gil

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Gil

Actually, algae needs both sunlight AND high levels of phosphates/nitrates to bloom as described. It's one of the reasons that detergeant manufacturers have cut down the amount of phosphates in laundry detergeant in an effort to control algae which in turn leads to large fish kills.

Is there a possibility that Mike's sand filter is just not up to the job of removing the fine sediment which may have come with all the rain? The sediment may have also been carried by the local water supply.

He says that the CL level in the pool is ok. Is there a chance the test kit/chemicals are out of date and giving a false reading?

Do you have some sort of test equipment for sale to test for ORP?

Mike

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What's your chlorine readings (chlorine, free chlorine)?

Somewhere between 6 and 10 ppm.....before the chlorine was added

is that supposed to be a joke? <_<

The short answer is no. My test strips read purple 6ppm and dark purple 10ppm, the colour reading was neither a normal purple colour, nor a dark purple colour, somewhere in the middle, so my conclusion was between the readings, hence I could not be accurate, apolgies for not being up to nobel prize winning chemist status....I will try harder next time.

Why bother to post as you did if you can't find something constructive or helpful to add? I am in the process of ordering a more professional test kit from the states, in the meantime I have to make do with test strips which are not accurate, so I'm sorry if my knowledge of chemistry is a burden to you. You must remember this "pool" thing can be quite daunting for beginners, as time goes on and one gathers helpful kernels of knowledge, one becomes more proficient in pool maintenance.....just think in maybe another 25 years I might be able to assist you Naam :jap:

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Yes, you can use EM ( Effective Microoranigms) which make the use of Chlorine or other chemicals not needed any more.Just look on Internet .EM was developped in Japan 20 years ago and is used by thai farmers.It is for sale in Bangkok and Chiangmai, and may be other places in Thailand.It is CHEAP, 80 bath for one liter.With one liter you can purify FOR ABOUT 4 MONTHS 10.000 liter of water, so if you have a small/medium swimmingpool 2 or 3 liter should do the job.Just pour 2 or 3 liter in your swimminpool, and after that measure the PH, which should drop considerably.

Try and let me know!

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Yes, you can use EM ( Effective Microoranigms) which make the use of Chlorine or other chemicals not needed any more.Just look on Internet .EM was developped in Japan 20 years ago and is used by thai farmers.It is for sale in Bangkok and Chiangmai, and may be other places in Thailand.It is CHEAP, 80 bath for one liter.With one liter you can purify FOR ABOUT 4 MONTHS 10.000 liter of water, so if you have a small/medium swimmingpool 2 or 3 liter should do the job.Just pour 2 or 3 liter in your swimminpool, and after that measure the PH, which should drop considerably.

Try and let me know!

Thanks for your helpful comments (unlike some :whistling: ) I'll look into and hopefully let you know,

Regards,

Mike

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EM is bacteria used to treat waste in septic tanks. It breaks down the solid waste, paper etc. I don't think it has any effect on urine. I have never heard of it being used to sanitize a swimming pool. It's available in most any city here in Thailand. I would be very skeptical about trying to use it in a swimming pool where people especially kids will be swimming. I have no idea as to the type of bacteria it is and I would not like to see the results if some kids takes in a mouthful of pool water treated with EM. Typically you have to mix the EM bacteria with molasses which provides the growing media for the bacteria before using the product. I know people who swear by it and use it regularly in their septic tank. I don't use it now but have used it in the past but didn't notice any great benefit from the product. That may be due to the fact that we installed a large black plastic underground tank which supposts bacteria growth to destroy the waste. I asume it works very well as we have not had to pump out the tank since installing it 6 years ago.

Additionally, you would have to remove the chlorine from the water first before adding EM because the chlorine would kill the EM bacteria.

I would say there are lots better ways to solve this.

Mike is this a very large pool? Have you given any thought to possibly draining it and refilling it to start from scratch. I realize there would be an expense involved but it may be the easiest & quickest solution. I would also give some thought to the type & grade of the media in your sand filter. I don't know how long this media lasts because I'm using a DE filter so have never experienced any problems with not being able to get rid of any sediment in the pool.

BTW: I'm using Hach brand Aquachek 7 test strips which are more than sufficient for the typical pool owner. It measures everything other than the salt concentration in the water. I purchased a saltwater aquarium hydrometer which reads from 0-40ppt to test for the salt concentration. Both available on EBay.

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EM is bacteria used to treat waste in septic tanks. It breaks down the solid waste, paper etc. I don't think it has any effect on urine. I have never heard of it being used to sanitize a swimming pool. It's available in most any city here in Thailand. I would be very skeptical about trying to use it in a swimming pool where people especially kids will be swimming. I have no idea as to the type of bacteria it is and I would not like to see the results if some kids takes in a mouthful of pool water treated with EM. Typically you have to mix the EM bacteria with molasses which provides the growing media for the bacteria before using the product. I know people who swear by it and use it regularly in their septic tank. I don't use it now but have used it in the past but didn't notice any great benefit from the product. That may be due to the fact that we installed a large black plastic underground tank which supposts bacteria growth to destroy the waste. I asume it works very well as we have not had to pump out the tank since installing it 6 years ago.

Additionally, you would have to remove the chlorine from the water first before adding EM because the chlorine would kill the EM bacteria.

I would say there are lots better ways to solve this.

Mike is this a very large pool? Have you given any thought to possibly draining it and refilling it to start from scratch. I realize there would be an expense involved but it may be the easiest & quickest solution. I would also give some thought to the type & grade of the media in your sand filter. I don't know how long this media lasts because I'm using a DE filter so have never experienced any problems with not being able to get rid of any sediment in the pool.

BTW: I'm using Hach brand Aquachek 7 test strips which are more than sufficient for the typical pool owner. It measures everything other than the salt concentration in the water. I purchased a saltwater aquarium hydrometer which reads from 0-40ppt to test for the salt concentration. Both available on EBay.

Mike, thanks for the advice there.

Pool is 15m x 5m x 1.74m. Y/day we filtered for 12 hours, today so far about 9. The water is way less green, but still not clear, still cloudy but much less so. So maybe in a day or so it will be back to normal.

As I said it's a sand filter, but if you can take all of the sand out and use DE in a sand designed filter then that could be a future consideration...is that possible Mike?

In response to your earlier questions, we have had a lot of rain here lately and we are surrounded by fields, I do encounter a lot of particles from the air going into the pool (the air flow is very good here) so perhaps it was an overkill of rain and particles which caused the problem or the chems were out of whack....I'll just have to see if it gets back to normal or not, appreciate your input and the other posters too.

Mike

Edited by mike1963
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Mike

I think you may be correct about the heavy rain effecting the pool water. We have had lots of rain up this way as well which has forced me to remove water from the pool on several occasions. I keep my Free Chlorine level about the same as you do and run my filters 4 hours in the morning and the same at night. Our pool is a bit larger than yours and I'm using 2 Hayward DE filters along with 2 Poolrite chlorinators running at 60%.

Unfortunately you cannot use DE powder in a sand filter because the filters are totally different. However, I have seen a lot of different media in the pool shops here in Udon Thani other than standard "sand" claiming better filtering ability. I would investigate changing your filtering media to a more effective type in an effort to prevent something similar in the future.

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Mike

I think you may be correct about the heavy rain effecting the pool water. We have had lots of rain up this way as well which has forced me to remove water from the pool on several occasions. I keep my Free Chlorine level about the same as you do and run my filters 4 hours in the morning and the same at night. Our pool is a bit larger than yours and I'm using 2 Hayward DE filters along with 2 Poolrite chlorinators running at 60%.

Unfortunately you cannot use DE powder in a sand filter because the filters are totally different. However, I have seen a lot of different media in the pool shops here in Udon Thani other than standard "sand" claiming better filtering ability. I would investigate changing your filtering media to a more effective type in an effort to prevent something similar in the future.

OK, good idea. Where are you living?

We are in Korat and I need someone with a pool business/knowledge/experience to be able to use their services e.g replacing the sand with a different media, I would not know where to begin! But if I had a competent, trustworthy pool outfit, prepared to come here, to rely on then that would be really good.

Regards for now,

Mike

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Algea is almost always a sign of low chlorine. However, there is a chemistry phenomenon that chlorine does not work efficiently in high pH water (above 8.0). Algae is sometimes seen in pools where there is a good chlorine level, but high pH. Knock the pH down with acid to release the killing power (oxidation) of chlorine. Keep alkaline in range to stabilize pH at 7.5.

You can shock a SW pool with either granular chlorine, or liquid chlorine. We like liquid chlorine, because its safe, easy, works quickly, then burns off quickly. However, if your pool pH is high, use the granules (90% strength); this is because this chlorine has a very low pH, and you will kill two birds with one stone (see first paragraph). You should try to learn about ORP, and begin measuring this instead of free chlorine. ORP takes into account the ph at the moment of testing sanitizer oxidation potential. All of our pools now have ORP sensors and pH sensors plumbed in.

Also, keep CYA in range, in 90% of all salt water pools, the owner is not familiar with CYA. Chlorine from a chlorinator is un-stabilized, and needs a supplemental stabilizer.

Cloudy water is almost always a filter problem. Don't backflush though, if pressure readings are normal. A little bit of dirt in the filter actually helps filtration. Check the pump impellor to make sure there is good cirulation rates (stagnant water goes green). There are no mysteries with pools, you will find the problem eventually.

Best,

Gil

All true but with one important omission. The culprit of high Ph is usually high Alkalinity and just adding acid in the usual ways or even using the powdered Cl2 will not effect the alkalinity enough in a one time dose to bring the Ph down to stable levels unless the acid is added in one place directly and not dispersed like the usual application. Test your alkalinity first and then make adjustments accordingly, the silt on the bottom is either algae fall out from some algae dying or it is potentially sand from a broken lateral in the bottom of the filter which can also aggravate or have even initiated the original problem..

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Mike

I think you may be correct about the heavy rain effecting the pool water. We have had lots of rain up this way as well which has forced me to remove water from the pool on several occasions. I keep my Free Chlorine level about the same as you do and run my filters 4 hours in the morning and the same at night. Our pool is a bit larger than yours and I'm using 2 Hayward DE filters along with 2 Poolrite chlorinators running at 60%.

Unfortunately you cannot use DE powder in a sand filter because the filters are totally different. However, I have seen a lot of different media in the pool shops here in Udon Thani other than standard "sand" claiming better filtering ability. I would investigate changing your filtering media to a more effective type in an effort to prevent something similar in the future.

OK, good idea. Where are you living?

We are in Korat and I need someone with a pool business/knowledge/experience to be able to use their services e.g replacing the sand with a different media, I would not know where to begin! But if I had a competent, trustworthy pool outfit, prepared to come here, to rely on then that would be really good.

Regards for now,

Mike

Cartridge filters these days are the best compromise to sand or DE and extremely effective.. Much more effective then sand and just slightly less effective then DE but much easier to maintain. Hayward cartridge is #1 for ease of maintenance,reliability and durability.

Edited by WarpSpeed
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Mike

I think you may be correct about the heavy rain effecting the pool water. We have had lots of rain up this way as well which has forced me to remove water from the pool on several occasions. I keep my Free Chlorine level about the same as you do and run my filters 4 hours in the morning and the same at night. Our pool is a bit larger than yours and I'm using 2 Hayward DE filters along with 2 Poolrite chlorinators running at 60%.

Unfortunately you cannot use DE powder in a sand filter because the filters are totally different. However, I have seen a lot of different media in the pool shops here in Udon Thani other than standard "sand" claiming better filtering ability. I would investigate changing your filtering media to a more effective type in an effort to prevent something similar in the future.

yes you can. i am using DE every 3 months for several days in a sand filter to filter out fine impurities. i just add a measure (volume approximately 1 liter) on top of the sand, increase pumping hours and backwash after 3-4 days. the discolouration of the DE, which remains on top of the sand, shows its efficiency. as simple as that.

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What's your chlorine readings (chlorine, free chlorine)?

Somewhere between 6 and 10 ppm.....before the chlorine was added

is that supposed to be a joke? <_<

The short answer is no. My test strips read purple 6ppm and dark purple 10ppm, the colour reading was neither a normal purple colour, nor a dark purple colour, somewhere in the middle, so my conclusion was between the readings, hence I could not be accurate, apolgies for not being up to nobel prize winning chemist status....I will try harder next time.

Why bother to post as you did if you can't find something constructive or helpful to add? I am in the process of ordering a more professional test kit from the states, in the meantime I have to make do with test strips which are not accurate, so I'm sorry if my knowledge of chemistry is a burden to you. You must remember this "pool" thing can be quite daunting for beginners, as time goes on and one gathers helpful kernels of knowledge, one becomes more proficient in pool maintenance.....just think in maybe another 25 years I might be able to assist you Naam :jap:

please be a bit less and mighty Your Honour especially after you demonstrated that you possess a wealth of "no idea" about pool water treatment.

you were asked about chlorine content and now you come up with "purple" meaning you are referring to the pH of your water. by the way, pH is not measured in ppm!

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Naam:

Yes indeed, I already held up my hands and said I know very little, if I knew it all like you mate then I would not be asking these questions in the first place. Yes, new to pools so need help....you don't want to help, then go and find another hobby instead of being a negative poster, all of the other posters have been helpful, apart from you

FYI, the strips I use, free chlorine ranges from a Tuscany cream to a Barney purple.

As I said, if you do not have anything constructive to add then don't post.....what's the point otherwise?

Edited by mike1963
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Naam I've never heard of adding DE powder to a sand filter but if it works for you great. However, It would seem to me to be a whole lot easier to either change your filter to a DE filter or change the media to a better media.

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Naam I've never heard of adding DE powder to a sand filter but if it works for you great. However, It would seem to me to be a whole lot easier to either change your filter to a DE filter or change the media to a better media.

i am not unhappy with the sand filter especially with the added use of DE which in my case is more than adequate.

reason: my pool is integrated in the house, i.e. completely enclosed meaning no airborne dust/dirt, leaves, frogs, rain, sunrays causing algae bloom, etc. contaminating my pool water. Cl content less than 0.5 ppm (formerly used H2O2), a Cl shock and DE every three months provide crystal clear and bacteria free water. daily pumping/filtering time 1.5 hrs only. disadvantage: from end of october till mid march i have to heat my pool.

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Naam I believe Mike's referring to the color chart on the test strip package.

that measures chlorine in ppm and the chlorine contents was "somewhere between 6 and 10pp before Cl was added"?

george, on 2011-08-11 21:05:49, said: What's your chlorine readings (chlorine, free chlorine)?
mike1963, on 2011-08-11 21:22:56, said: Somewhere between 6 and 10 ppm.... before the chlorine was added

i rest my case! :lol:

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[quote name='Naam'

i rest my case! :lol:

And it came to pass, that Naam was chosen to speak with The Lord (well he wasn't really chosen, he just told everyone that he was an authoritative expert on everything and they believed him.....you know how these things go) about his people.

And The Lord spoke unto Naam and said, "Naam, you are to do this one final act for me and your people, the people of Posting Land, I shall only ask this of you once, and once only, not twice, nor thrice, once and once only, I expect you to obey the will of your Lord". "What would you have me do My Lord" Naam asked gingerly.

With great flashes of lightning, deafening claps of thunder, swirling rains and howling winds, The Lord spoke unto Naam and said...............Naam, GO FORTH, GO FORTH INTO THE WILDERNESS, GO FORTH AND MULTIPLY, GO FORTH AND MULTIPLY AS MANY TIMES AS YOU SEE FIT."

And the peoples of Posting Land hoped and prayed that Naam would do as the Lord had asked and GO FORTH AND MULTIPLY.

Michaelmus 15:8

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If you are considering changing the sand in your filter go for glass filter media. It is more expensive than sand but much better. Check it out with Google. I recently had a similar problem with a customer's pool & in the end we added flocculant which cleared up the problem.

Edited by Valentine
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And the peoples of Posting Land hoped and prayed that Naam would do as the Lord had asked and GO FORTH AND MULTIPLY.

Naam however couldn't care less what the people hoped for. he remained in his chosen place, vowed to continue to enlighten the ignorants and point out rubbish if and when presented whether the infidels liked it or not. needless to say that the infidels did not like Naam's questioning and kept on shooting their own feet the blooming algae in their pools with... deep purple coloured parts per million.

av-11672.gif

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