Water treatment

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mikethaisun

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LifeTime Supporter
Feb 24, 2009
73
North East Thailand
Hello,
I am new to this forum and new to pool maintenance, I am amazed at the volume of material that is available to help me but am not clever enough to sift out what I need to know.
I live in Thailand and have an inground pool, it is approximately 12 meters long, kidney shaped with an average width of about 4 meters. The lowest depth of water is 1.6 meters and 1 meter at the shallow end. I calculate the volume of water to be 13000 US gallons but could wrong! You maybe able to calculate it more accurately. The pool is of conrete construction with a fully glazed tile floor and walls. Our average temperture during the day is roughly between 30 and 37 degress celcius.

I have a sand filter with a 1.1kw pump to run the system. Water that leaves the pool is collected around the perimeter through a slotted plastic drainage syestem that returns the water to the charging tank. I am told this is not a skimmer system.

I have been using a droplet method for checking the Chlorine and Ph content in the water. This method shows coloured levels of each chemical and the test checks always turn out to be on the low side.

My main question is how much of each chemical do I add for each check level to get to the right amount required for clean and healthy water.
The Chlorine level is graded from 0.3, 0.5,(add) 1 to 1.5 (ideal) and 3.0
The Ph level is graded from 6.8 (add) 7.2 to 7.6 (ideal) 7.8 to 8.2 (add acid) what acid do I add if needed, never has been yet.? In these temperatures how often should I test the water?

I checked the pool today and had a chlorine level of between 1.0 and 1.5 (ideal) The Ph level was in the 6.8 level, How much soda ash do I need to add to get to the right amount.

I note from reading the material contained in the water testing section that there a few different methods for checking chemical levels, which would be the best for my use in the area and temperature zone where I live?

I have been sold Trichloroisocyanuric acid 90% min as Chlorine produced in Japan and Soda Ash (light) NA2 CO2 99.2% min.produced in Korea. Are these suitable? We live in a very rural part of Thailand and getting supplies of chemicals can be problematic, a trip to Bangkok (800k's) there and back will probably have to be undertaken.

As I stated previously, I am not blessed with a naturally high degree of intelligence and would hope that I do not need a diploma in chemical engineering to understand what I need to do. So, if help is available can it be presented in the most simplistic manner possible.

I expect the answers to these questions are probably somewhere in the Pool School forums but I have not been able to find them.

I do hope that I can get the information I need and any other suggestions that will help

Thanks for taking the time to read this.
Regards
Mike Court
 
Hello Mike and welcome to TFP!

You need to know that the amounts you add, particularly when adjusting pH are not easy to calculate because there are many variables that affect it.

The key piece you are missing is the effect of Cyanuric Acid (CYA) on your required chlorine level. CYA is a component of Trichloroisocyanuric acid. It stabilizes the chlorine against UV light, but it accumulates in the pool and it restricts the effectiveness of the chlorine as it reaches higher levels. Check out the chlorine/CYA chart in Pool School http://www.troublefreepool.com/category/pool-school/chlorine_cya_chart_shock It will show you that minimum safe free chlorine levels are usually much higher than the 1 to 1.5ppm shown on your test kit. Trichlor users usually find their CYA to be well over 100, requiring chlorine to be maintained in the area of 10-12ppm, which is probably outside the range of your test kit.

For pH adjustments, which you need to do pretty quickly to avoid pool damage, you need to know the Total Alkalinity (TA) of the water. TA acts as a buffer to pH change, and since your pH is low, it PROBABLY indicates that your TA is low. TA is essentially baking soda, and raising TA is done by adding baking soda to the pool.

Try using the Pool Calculator at poolcalculator.com to figure your soda ash requirements for pH increase. Borax is a better choice for pH increase if your TA is already high.

The bottom line is that you need to test for more than you are currently testing for. I don't know about test kit availability in Thailand. The kit available at TFTestkits.com is a good one, or the Taylor K-2006 will do the job as well. Duraleigh, the owner here also owns TFTestkits, but regardless of your test kit, we'll be glad to help you figure out what's going on with your water.
 
Hello John
Thanks for your prompt reply. The colour of my pool water this morning is a pale shade of green? The Chlorine level is zreo but the Ph level is still 6.8.
When the pool installer completed the work he told me to check weekly using the drops method and if necessary throw in a couple of cupfulls of either Chlorine or Soda Ash depending on the colour scales of the test kit.
He also left two other chemicals, one is a liquid labelled Sodium Hypochlorite/Highclor and a powdered form of Alluminium Sulphate. Are these of any use to me at this time bearing in mind I do not know what Borax is or where to get it, I maybe able to get Baking Soda.

In the advise you kindly gave me you said I should check CYA and TA levels, do I need one of the test kits you recommend to do this? I have contacted Taylors who do not have any distributors in Thailand, I can get some strips from Bangkok as a stop gap, what do you suggest.

The first batch of Chlorine I used was Dichlor granules which reacted a lot faster and did not need topping up as much as the Trichclor powder which is best to use? Dichclor was twice the price of Trichclor!

We are now into the hot season in Thailand and daily temperatures are in the high nineties so the pool is a very welcome retreat. The water is pale green but clear and there are no visible foriegn bodies in it. Is is OK to use or should I close it down until I can get a good test kit and suppliers of chemicals.

I apologise if some of what I write is not very clear but hope you will be able to advise a speedy remedy to the problem.
Regards
Mike Court
 
You are in the beginning stage of an algae bloom, and you need to get chlorine into the pool quickly. The Sodium Hypochlorite you have is a good choice to quickly raise the chlorine. It's a stronger version of laundry bleach. Your chlorine needs to get up in the 15ppm range fairly quickly or you are in for a mess.

You can't get by with weekly testing of chlorine levels. You need to test at least once a day, and probably twice a day until you get a feel for it.

If your pool is new, you may not yet have CYA problems, but you need to be able to test for it. I'll PM Duraleigh and have him check this thread about the availability and cost of his kit there.
 
I just wanna add to the replies so far.

You are definitely going to have an algae bloom and it is vital that you take action immediately to avid a break out. Algae control is very important and it can cost a fair amount of money to rectify if left alone for too long.

You need to add chlorine and maybe a little more than normal, leave the water for a while and then do a PH check. Once you have done the check you will have to take the next step in maintenance such as more chlorine or acid.

Hope that helps :)
 
Thanks John T and Oscar D
Your comments and advice are most appreciated. At this time of the year in Thailand when the farmers are getting their fields ready to grow rice there is a lot of burnt chaff embers and dust from ploughing in the air and my pool seems to be a receptacle for it all, I therefore keep it covered when I am not using it.
This morning I took the pool cover off and noted spores clinging to the side of the pool, I brushed them off and added about 2.5 liters of Sodium Hypochlorate, this has cleaned the water and it is now clear again with no hint of a green colour. The cover is a heavy PVC material and stops the entry of dust and leaves but will it have an adverse effect on the chemicals in the pool?
I recovered the pool and checked for Ch again this afternoon, there was a minimal rise in CH but not enough to make a real difference, the Ph level had not altered and is still only 6.8. I have now added 2 liters of bleach to see if that has any effect.
I note that your advise is to add chemicals through the skimmer system, I do not have a skimmer, should I add chemicals through the recycle tank or direct into the water?
I have ordered a test kit from Duraleigh but it may take a few weeks to get here. Your previous advise was to increase the CH level to about 10ppm, as my test kit only goes to 3.0 should I triple the amount needed to reach 3 in order to get close to 10?
I am fairly confident that I can get Baking Soda albeit in small quantities, and Bleach is readily available but there is little difference in the cost as against Dichlor. Borax, I am not sure about where I can get that.
I will probably run out of my remaining stock of Trichclor and Soda Ash in the near future before I can replenish stocks, how badly will that effect the water in my pool even if I keep it covered until supplies have been received.

I have become a TFP supporter and thank you for your help so far.
Regards
Mike Court
 
You can add bleach/Sodium Hypochlorate by pouring it slowly in front of a return while the pump is running. Most of the powders can be pre-dissolved in a bucket and then slowly poured in front of a return.

You don't want to leave your PH that low for too long. You can raise PH with soda ash. Dichlor and trichlor both lower the PH, so you typically need to be adding soda ash regularly as long as you are using either of them. It is important to keep the PH above 7.0. Ideally PH should be around 7.5 or 7.6, but that is not as critical.
 
Thanks Jason
Please excuse my ignorance but what is a return? My pool has a concrete channel around the perimeter to catch run off and returns water to the holding tank. Should I add the bleach/Dichclor etc. where the channel funnels into the tank.
I apologise if I am being thick but this is all new to me. I have had the pool for 2 years and before this month I have never had a problem with the water cleanliness.
Regards
Mike
 
Hey, Mike,

A return is the opening thru which the water is "returned" to the pool.

The returns are probably a little better for adding chems than the channel you're talking about.

Do not overlook your low pH very long.....20 Mule Team Borax is a laundry additive and here in the US, is commonly found in most grocery stores. Soda Ash is around if you look hard for it. You might google "soda ash" and "thailand" and I'll bet you'll find it.

Read thru the articles in "Pool School" there's a wealth of info in there.
 
Hello Dave
Thanks for the advice, I think I can get Soda Ash fairly easily although its a 250k round trip to get it!
As regards the return system to the pool, my returns are all under water and out of reach so I have been disolving Chlorine powder and Soda Ash then poring it in from the side of the pool. Is this OK?
Regards
Mike
 

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my returns are all under water and out of reach so I have been disolving Chlorine powder and Soda Ash then poring it in from the side of the pool. Is this OK?
Click to expand...
Sure. The idea is you are quickly diluting and evenly mixing the chemistry into your pool.

I have a question for you. You and SPP (from Thailand,also) both have "holding" tanks. I'm not sure I understand their purpose or how big they are. Is it easy to explain? They virtually do not exist here in the states.
 
Hello Dave
Thanks for your comments.
My 'holding tank' is a seperate chamber constructed at the end of the pool and is used to add fresh water from the mains and stored there to top up the pool when necessary. I think this chamber is also used when recycling water through the sand filter. It holds approximately 8cm.
I hope this is of use to you.

Having read through the BBB section of the Pool School it seems that ordinary bleach is the best form of chlorination as the others seem to have added side effects in lowering pH and TA. The Dichclor granules costs about 272$ per 50 kilos and the Trichclor powder was 151$ per 50 kilos. I have not managed to get a cost of buying Bleach other than in 2 liter bottles at 2.12$ a bottle. If I have to use twice the amount of liquid bleach to the chlorine powder or granules it may be more expenxsive. Do you have a similar situation in the States?


Regards
Mike
 
Holding tanks are used to keep the water in the pool at a uniform level even though water is evaporating and getting splashed out. The plumbing is setup to hold the pool at a constant level, while the level of water in the holding tank varies. The trough in an infinite edge system serves the same purpose (in addition to it's more obvious purpose of catching the spill over).

In the US, bleach costs a little bit more than trichlor if you count things based on adding the same amount of chlorine. After taking the additional costs of maintaining the PH at a uniform level, bleach is a better deal than trichlor.
 
Thanks Jason
I think I am nearly there, my pool has now returned to a normal colour and looks to be free of the green stuff. Thanks to all of you for your helpful comments and advice.

I have added Soda Ash and Chlorine. The chlorine level is now above three as the colour is deeper than that in the test tubes, Soda Ash is still showing to be deficient at 6.8, I have added approximately 7kgs (pool size 78000 liters) how long should I have to wait before testing again.

Do you know any members in Thailand as I am having trouble in finding Borax, maybe they would know where I can buy it.

Thanks again
Mike
 
We have a couple of members from Thailand: frankthailand and stevehaigh both mention that they are from Thailand. I seem to remember at least one of them also having problems finding borates, though that was a while back and I can't find the specific topic.
 
Hello Jason
Hopefully this will be my last question for a while as I think I troubled you enough just lately.

I am trying to get the pH level to the correct amount, I have worked out that my pool holds 78000 liters. Using the pool calculator, if the level at present is 6.8 I need to add approximatley 4 Kgs of Soda Ash, I have added double that amount but still get a low reading on the test kit.
Am I doing something wrong or not doing enough, I would appreciate your advice on this
Regards
Mike
 

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