Green Pool in Thailand

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exception

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Oct 26, 2015
11
Pattaya, Thailand
Hi

I have just taken over a pool which has been off because of a problem with the SWG controller. This is (hopefully) now fixed (replaced burned out connector) so I would like to get the pool usable again. We are expecting guests in a week so my wife is on my case.

Prior to the SWG problem there was a pool guy who used to maintain it. He used sulphuric acid to adjust the PH, as far as I know that's all he ever added, he said he needed to add a little every few weeks. He stopped coming back in July around the time the SWG packed up. The water was also cleared about a month ago by a well meaning neighbor who was convinced it just needed a shock (before I found the burned out connector). He put in Trichlor and something to make the dead stuff sink and to be fair made it look nice, but with the salt cell not working it reverted to green within a week.

It's been rainy season here for the past month, the pool kept overflowing into the garden so I let out about a third of it, I figured it wouldn't hurt to lose some of the water as I wasn't sure what was in it. The rain has refilled most of it but it could take some more, perhaps another 3 inches. We have a borehole in the garden so no problem for water.

The pool is now very green and murky. I am now hopefully going to sort it out following the advice of this forum :)

I am pretty sure I need to follow the SLAM process to start with, however I can't find a test for CYA or the FAS/DPD kits here in Thailand. I have just ordered a Taylor K-2006 online but i have no idea if it will make it through Thai customs and even if it does it will take a couple of weeks and if I can do something in the meantime my life will be easier.

So I have at the moment only got OTO and Phenol for total Chlorine and PH. Is there anything I can do with just these? The general consensus here is just chuck in some Trichlor but i'd rather not ...
 
It's super hard to make any kind of meaningful changes without a proper test kit. What is the water situation like where you are located? Replacing the water may be the best option if you need the pool looking good quickly and do not have access to the proper tests before your deadline.
 
Hi thanks for the reply pinguy. Emptying seems drastic but could be an option - we are on a borehole so refilling is not so much of a problem. The only issue i see is that I think we have a waste tank under the garden somewhere but obviously it will not hold the full pool volume so I don't know where the water will go after that...
What process would I need to follow to empty and refill - should I let the sides and bottom dry out completely in the sun to kill the algae and then scrub it before refilling? Is there anything to use/avoid for this?
Alternatively I have plenty of sodium hypochlorite, and about 3kg of 90% TCCA, I can probably pick up a DPD test locally which will at least give me a clue about FC/CC levels, but my sticking point is not knowing CYA level and therefore the correct shock FC level to aim for. I only can estimate that the pool had 2kg of 90% TCCA added a month ago and since then about 1/3 of the water was drained out and refilled with rainwater. I can't be certain about CYA level before this as I have only been in the house since May. Is there a rule of thumb shock FC level to aim for without knowing the CYA level for certain? Or a way of monitoring the relative FC/CC levels to see how much sodium hypochlorite to add?
 
Agreed that you need to SLAM the pool to kill the algae. But, you have to know the CYA level to know what the shock level is and you have to be able to test FC to know how much chlorine/bleach to add. Waiting for the K-2006 test kit is the best option.
 
exception said:
Is there a rule of thumb shock FC level to aim for without knowing the CYA level for certain? Or a way of monitoring the relative FC/CC levels to see how much sodium hypochlorite to add?
Click to expand...
Unfortunately not, because the effective FC level is calculated as a % of CYA in the water.

If you did choose an arbitrary CYA level, I'm pretty sure the only risk would be wasting a lot of bleach without having much effect on the Algea. I don't think anyone here would recommend that though.
 
OK so the landlord came round today and apparently the last time the pool went green it was very expensive for him to replace the grouting on all the tiling. Something to do with it getting too acidic? Anyway he has made the decision that better change the water now than wait for the test kit to arrive so the pool is emptying as I write this.
Which process do you guys recommend I should follow to clean the pool before refilling? Most of the algae seems to be lying on the bottom so this is easy to sweep out with the waste water and where I have done so in the shallow end the ceramic tiles are already looking nice, but the white grouting has got the algae sticking to it. Should I leave it to dry in the sun or is there a recommended cleaning product to get rid of it? Any other tips?
 
Hi all, I have now drained and cleaned the pool, it is currently refilling direct from the borehole. I have read several helpful posts on the forum and it seems like I probably ought to SLAM the pool first as there is almost certainly residual algae to get rid of. Also I should probably do this before adding salt and then only switch on the SWG when the salt has had plenty of time to circulate? Does this sound about right? The only problem is that I still only have the OTO and PH test kit :(

My working plan is:

1) Check and adjust PH - I measured the fresh water filling the pool as <6.8. I figure I should aim for 7.6, I will add Soda as per the Pool Calculator once the pool is full
2) Add Trichlor to shock level. At the moment the CYA should be 0 ppm as the water is fresh but the Trichlor adds CYA so I am not sure what my target FC value should be? I need this so I can get the correct amount of Trichlor to add from the Pool Calculator
3) Without the FAS/DPD test I realise it is difficult to know when the SLAM process is complete. Is there any helpful information that can be gleaned from the OTO test or do I just work on adding extra Trichlor for good measure?
3) After some period of time [how long?] add the salt to 4000ppm & circulate for [12 hours?]
4) Switch on SWG & monitor salt level

Obviously any advice very welcome!
 
Some initial thoughts to your last questions:
1) Adjust pH to about 7.2 since you know you are going to SLAM
2) It's best to use granular stabilizer/conditioner (cyanuric acid) to increase your CYA if available to reach your initial target (i.e. 30ppm) quicker and accurately. Start this as soon as you fill the pool. Relying on tabs will take a while.
3) The OTO will tell you if you have chlorine in the water, and perhaps help confirm up to 5 ppm, but not at the SLAM level of say 10 ppm.
3) (again) ha. I suspect you can add the salt at any time. It should not have any bearing on the SLAM
4) Leave the SWG off during your SLAM. SWGs are not designed to maintain the high FC levels required anyways. Stick to just regular bleach until the SLAM is complete, then let your SWG start producing FC for you.

Your biggest limiting factor right now is the lack of the FAS-DPD to test FC at levels of 10 or above. You really need that part. Hope this helps.
 

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OK now I see the bit at the bottom of the PoolMath calculator . . basically even if I add all the Trichlor I have (about 2.5kg) the CYA level will only get to about 20ppm which is lower than recommended level for a SWG pool. So I will need more CYA for sure. I will aim for starting FC of 10ppm which will be inline with my low CYA level. Using Trichlor for this will raise my CYA to 6ppm.
 
Last night (Just to clarify I am UTC+7) I added 1.2 kg of soda ash as the pool was filling and 1kg of TCCA. The TCCA is in a tub which says "90% TCCA - Trichloroisocyanuric Powder". It doesn't mention any other chemicals and it is not marketed as a "Shock" treatment so I guess it is probably just what it says it is. The TCCA would increase the FC to 13ppm and the CYAppm to 8.2 based on the pool being full and assuming starting levels of 0 ppm for both. I added the chemicals as the pool was filling and when it was about 1/2 full with the pump circulating the water.
This morning the pool has a very green tint to it. When I brush the bottom I can see a light green sediment getting kicked up. The colour of the water makes the white brush appear to have a green tint when it is deeper than about 18" but the water is still clear to the bottom. I would estimate that the pool is currently 70% full.
This morning the PH read 7.2. Thanks pabeader for the link about the extended OTO test, I performed a few test this morning, the colour reference I have is up to 3ppm:
1. Standard test - fill to mark + 4 drops of OTO: > 3ppm, colour went straight to deep yellow and didn't change
2. 50% diluted + 4 drops OTO: > 3ppm, colour went straight to deep yellow and didn't change
3. 50% diluted + 2 drops OTO: > 12 ppm, colour went lighter yellow first then developed a more reddish tint. The bright yellow was close to the max reference colour, the reddish colour not comparable.
4. 50% diluted + 1 drops OTO: > 24 ppm, colour went lighter yellow first then developed a more reddish tint. The bright yellow was close to the max reference colour, the reddish colour not comparable.

My hopeful guess is that I still have plenty FC as evidenced by the initial bright yellow and that the green tint is dead algae which will clear with filtering time, does this seem right? Any suggestions for next steps, should I continue filling or circulate it as it is? Or drain and start again?!
 
A possibility which has just occurred is that the sediment is from the new water - the main borehole pumps into an IG plastic storage tank, controlled by a float switch. When the storage tank gets low the water in the house can get a little brown / cloudy so I guess there is sediment in the storage tank. To speed up the filling process I dropped a submersible pump directly into the storage tank and ran a hose to the pool - thinking about it now of course I probably just transferred any sediment straight to the pool :( . . something in the water is still making it look green though?
 
just repeated the OTO test: 50% diluted water + 1 drop OTO and it went straight to a yellow colour which is almost the same as the 3ppm reference colour - so presume this mean total chlorine of <> 24ppm. Couldn't discern any changes from pale to darker yellow this time. maybe no FC? The water has a chlorine smell, the pool is now 90% full. I had it just circulating most of the day to see if the green tint would clear and to get the sediment off the bottom, it does seem to have improved. It's had the sun on it most of the day too. Now the question is whether I should add more TCCA, i.e. continue the shock process? Test kit not expected for at least another week, no further chemicals added since last night..
 
I suspect that the OTO method just isn't going to produce the accuracy in FC testing you need. That along with the fact that you are forced to estimate your CYA level based on the TCCA additions makes conducting a SLAM very difficult for you. There should be no green in the water. If there is, and it brushed-up when you sweep, it's live algae. No amount of filtering or running the pump will clear the water. Proper chemistry is the only way to kill algae, and it is critical to know the exact FC and CYA level to do that. I suspect obtaining the proper test products is a challenge for you at your location, but you should keep working towards that goal. Also, pumping-in water from your borehole or any other source can be tricky since you don't always know if there are metals (I.e. iron) in the water. Metals can have an effect on water tint/color and future management.
 
thanks again Texas Splash. I know you are right and that accurate testing is the way to go about it, I really do appreciate that I need the FAS/DPD test . . . I have ordered online but I still waiting on shipping and customs clearance which will likely take several more weeks . .

As mentioned above I had to drain the pool previously as the landlord was not happy with it being a pond and I had to refill it as it is otherwise a safety hazard for my young children . . . now it looks like it will go green again unless I do something?

If I can't get the pool working myself I will get pressured into contracting a local pool maintenance company instead; as an example the previous pool company told me straight out that sulfuric acid is standard acid to use in SWG pools in Thailand. I have also heard that they simply shock with Trichlor whenever the water looks green, there must be something I can do that is better than that option? . . I was hoping the knowledgeable people on this forum would be able to help my to limp through until the FAS/DPD test kit arrives :)

Unless there are better suggestions I think maybe the following:
1) Add the remaining Trichlor (about 1.5 kg) which will raise the FC by 20 and the CYA to 20ppm total
2) At the same time add the salt to 4000ppm
3) Pump / filter for 24 hours
4) Adjust PH to 7.6 with Soda Ash or Hydrochloric acid as appropriate
5) switch the SWG on
6) hope the proper test kit arrives promptly

Obviously any input on the above welcome, I will see if I can get some CYA also. The thing I am concerned about is whether I am making the Chlorine level too high and the water unsafe to swim in?
 
hi all. this a continuation of the situation so keeping it in the same thread..
the short story is that I had to go away for 3 weeks immediately after filling the pool and I had someone take care of the chlorine levels while I was away. I kept a table of the readings they took which were generally near to shock levels for the whole time as best as could be determined using the "extended" OTO test. When I came back there was green (algae?) noticeable on all the grout between the tiles across the bottom of the pool even though the water was crystal clear. Is it possible this is the "root" from when the pool was previously green which had not been killed?

I immediately set the SWG to 100% + BOOST and started brushing and vacuuming but the green doesn't easily brush off it almost seems to be like the grout is stained? See below, shallow end cleaning has been partially successful but some of it just wont come off, the deep end is practically impossible:

ShallowDeep
grout_shallow.jpggrout_deep.jpg

The FAS/DPD test finally arrived and I tested the water yesterday:

FC 32
CC 1.0
CYA 50
PH 8.2 (assume not reliable)
TA 80
CH 75

I would appreciate any suggestions please.
 
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