High load commercial pool

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joeanho

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Dec 5, 2017
29
malaysia
Hi,

I am based in Kuala Lumpur, Malaysia and pool care here is very primitive and basic.

I run a small swim school catering to swimming classes for mostly babies and preschoolers. My pool is 4 feet deep and size of 40 feet x 25 feet. We have a load of around 700 bodies in the pool each week (parents need to be in the pool with their babies).

We have 2 SWGs and pump is running 24/7. It has been quite tricky to care for our pool since Day 1 and we have changed a couple of pool operators. There are no test kits available here except the OTO test that we are using. The test kits that are recommended here (Taylors and TP-100) cannot be shipped to Malaysia due to custom laws. The chemicals available here are very basic ones only. There are no pool shops to get pool water tested in.

Recently my pool has had a green tinge but clear water for the last month. 5 of my swim teachers have complained of dry, itchy skin breaking out in a rash. kids have stinging eyes from opening the eyes in the water without goggle. We spent $80 to get our pool water tested in a lab and these are the results.

PH 7.35
TDS 5002 mg/L
Free chlorine 0
Chloride as CL 3356 mg/L
TA 67 mg/L
Hardness 155 mg/L
Total Coliform 23 MPN/100L

The Coliform present is worrying and I am thinking should I drain the pool and replace the water? I don't know why there isn't any free chlorine when my total chlorine is high. I don't know what else to do. My Total Chlorine according to the OTO test is 3.0

Thanks
Joanne
 
Hi Joanne! Welcome to TFP!

I loved Kuala Lumpur and all of Malaysia. Kudos to you for your honorable work teaching little ones to swim. What a challenge you have there, maintaining a big pool without a proper test kit. Wow.

I'm going to defer to the more experienced experts here, I'm just bumping your thread. Looks to me like you have a CC problem. Which would account for your mystery FC and TC levels, and the stinging skin and eyes, too, but we'll need a sharper set of eyes to confirm that.

Do you have access to liquid chlorine? I think your bather load is exceeding your SWGs capacities, so you're going to have to supplement them somehow. Or perhaps one of them has stopped working and this is the result.

I think you're going to have to SLAM Process your pool, but I don't know how to do that with an OTO kit.

Stand by...

:bump:
 
Is the pool indoors or outdoors?

What type of environment is the pool in?

What model SWG do you have and do you know what the CL output capacity is?

Unfortunately your testing did not give your CYA level. Do you know if any CYA (stabilizer) was ever added to the water?

Draining and replacing the water periodically may be the best for you if you can’t do proper testing and check the water sanitation. Is access to clean water a problem for you?
 
Thanks for the quick replies. My pool is indoor and it is above ground concrete pool with tiles.

I managed to purchase a CYA test kit from amazon and CYA is 0. Black dot is super clear at the bottom of the tube.

My pool is only 15 months old. The SWG output is 45 each (not sure what units those are - but I was told it’s the biggest capacity) and one of them is brand new as I only installed it last month when one wasn’t enough. I also have a chlorine tablet feeder. The chlorine added (if needed) is granular chlorine of 65% (that’s what the pool guy told me).
 
An indoor pool does not get the suns natural UV rays to burn off CC that form when the chlorine does its thing. Your high bather load is creating CC causing the stinging. Indoor pools often have a UV systen to artificially do what the sun does in outdoor pools. Do you have a UV systen in your water flow?

Dichlor and trichlor tablets contain CYA as well as chlorine and will raise your CYA over time if you use the tablets. A bit of CYA is good. Too much CYA can create problems for you.

Do you know how many gallons of water your pool is?
 
I managed to order a Taylor’s FAS DPD test kit from Amazon. Hopefully it will arrive in a week. That’s the only one kit that they can ship to Malaysia. I looked at Pool School and SLAM articles. Since my pool is an indoor pool CYA is 0 now. Do I have to increase CYA to 30 to start slamming ? From what I know from the pool guy we cannot buy Cyanuric Acid in Malaysia. The only way to add CYA is thru the chlorine tablets. May I add it’s a heated pool too if it’s of any concern.
 
Here is an excellent thread for you to read, especially the posts by JoyfulNoise. He really knows his stuff (but don't tell him I said so! ;) ):

Cc slamming ?

Good job on ordering the Taylor FAS DPD test kit. With the CYA kit, and access to the lab tests periodically, you'll be in pretty good shape. Your OTO kit can give you the pH reading you'll need regularly. You can test CH and TA less often.

Add CYA with the tablets, that's fine, then switch to liquid chlorine when you have enough CYA.

I can't advise you about coliform, maybe someone else here can...
 
Being an indoor pool you don’t need CYA 30 for the SLAM Process. CYA does help buffer the chlorine harshness.

We usually say a pool is safe to swim in up to SLAM Process [FC/CYA][/FC/CYA] levels. In your case I would keep people out of the pool while you have elevated chlorine levels.

Do you have a source for liquid chlorine?
 
I would have to ask the pool guy about liquid chlorine. Yesterday I added 16 L of household bleach (about 4 gallons)- I used the pool calculator for this volume to achieve a SLAM level of 10. This morning the total chlorine according to the OTO test back down to 3.0 (as it was before I added the bleach). What does this indicate if anything? I would have imagined that total chlorine would be higher than that.
 

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Household bleach is liquid chlorine. Just make sure it has no additives of any kind. Do you know what % chlorine it is - 6%, 10%, 12%?

Loss of FC indicates that the CL is being actively used in killing algae and other organics in the pool. That is why the instructions for the SLAM Process say to continue with the SLAM Process until the pool is clear and you can pass an Overnight Chlorine Loss Test. When FC stays steady and no longer drops it indicates the pool is sanitary.
 
I used Clorox plus a generic brand as they didn't have enough stock of Clorox! The generic brand states its 5.25%. Clorox I think it's 6% from what I googled. Yes that's what I was thinking too the chlorine is all used up but then wouldn't it become CC thus my TC would still be high? But I don't have a free chlorine test kit yet so I can't keep testing FC and to do the overnight chlorine loss test.

My pool guy uses granular chlorine if we need to add chlorine in. He said it's 65%. Can I used that to shock instead of liquid chlorine?
 
Clorox bleach is a problem in the US where all the Clorox bleach says "Contains Cloroxmax Technology". Those are polymer additives that create foaming. We don't recommend that Clorox bleach be used in pools here in the US. Read your label carefully.

I would use the generic brand of bleach if the label does not say it has any additives.

Problem with granular chlorine of 65% is what the other 35% is. It is usually CYA or calcium. Using too much of it will give you high CYA or calcium both of which can only be rid of by draining your pool.

Keep doing the best you can until you get your Taylor DPD test kit.
 
Oh dear.. I did not know that about Clorox. I think the 65% has calcium but my CH is low only 155. Since I added my 2nd SWG a month ago I have not had to add any granular chlorine. Now my 1st SWG ins't working well as the cells need replacing only after 15 months!
 
What brand/model SWG do you have? I dont know if we will be familiar with it in the US.

What % generation do you run the SWG at?

You should have a CH of 250-300 to protect your tile grout.
 
Maybe some of our Australian membets can help with the specs on your SWG.

How many hours a day does your pump and SWG run?

A SWG is designed to generate chlorine for a certain number of hours. If you run yours at close to 100% for 24 hours a day 7 days a week it cannot be expected to last long.
 
Sounds like you need an extra SWG for the heavy bather load. Probably easier than adding the amount of liquid chlorine a commercial pool will require.

PS: Id think carefully before adding CYA to a commercial pool. CYA is banned from commercial pools in the US for good reason. It slows the sanitizing effectiveness of chlorine. In residential pools this isn’t a big deal, but in crowded pool, rapid killing of germs, bacteria, etc is critical to preventing transmission of these organisms. There really isn’t any reason to have CYA in a pool that doesn’t see sun.
 
spoonman said:
Sounds like you need an extra SWG for the heavy bather load. Probably easier than adding the amount of liquid chlorine a commercial pool will require.

PS: Id think carefully before adding CYA to a commercial pool. CYA is banned from commercial pools in the US for good reason. It slows the sanitizing effectiveness of chlorine. In residential pools this isn’t a big deal, but in crowded pool, rapid killing of germs, bacteria, etc is critical to preventing transmission of these organisms. There really isn’t any reason to have CYA in a pool that doesn’t see sun.
Click to expand...

If you are adressing the OP, she has 2 SWG installed in her pool. See post #4.
 

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