High load commercial pool

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spoonman said:
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.
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I am not sure if this is accurate. I am going to do so rereading on this subject and ask our main "science" guy to chime in.
 
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.
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kimkats said:
I am not sure if this is accurate. I am going to do so rereading on this subject and ask our main "science" guy to chime in.
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CYA is NOT banned in the US from public pools. All pools are regulated at the local level either through county or city health codes and so the recommended use of CYA can vary by jurisdiction. Very few outright ban the use of CYA. Pathogen kill times are not slowed by the use of CYA - CT kill times are dependent on the FC/CYA ratio and so it doesn’t matter what the absolute CYA concentration is as long as the FC/CYA ratio is at the correct value. This is a HUGE source of misunderstanding in the industry and why CYA use is sometimes restricted - ie, the key concept of the FC/CYA ratio is ignored by most of the industry.

There is a VERY good reason to use some CYA in an indoor pool - it acts as a chlorine buffer and makes chlorinated water much less harsh on the eyes, skin and bathing suits. Water with zero CYA in it and an FC if 1ppm is 5 times more harsh than water with a 7.5% FC/CYA ratio. You also create more DBP and THMs faster in water with no CYA.

TFP recommendation is for indoor pools (as well as hot tubs) to use a maximum of 30ppm CYA in the water.
 
To the OP -

You should consider purchasing and installing a large UV sterilizer for your pool. It can be run in the off-hours of your business and it can help to greatly reduce bather waste. The biggest concern for your pool is the transmission of cryptosporidium which comes from human fecal matter. Crypto spreads through the sporolation (spore forming) of oocysts which are highly resistant to chlorine sanitation. Giardia is also another disease that can be a problem. UV sterilization can quickly and efficiently destroy chlorine resistant pathogens as long as the power and size of the unit is correct for your pool volume and pump turn over rate.
 
FAS-DPD kit and Slam questions

I own a small swim school in Malaysia and been having problems with high CC levels.

I just got my FAS DPD kit and have a few questions.

1. Would the water in the tube turn completely colorless ? I find it turns colorless and a about 20 seconds later it’s a bit pink again.

2. My CC is high. Even at 20 drops (25 ml test water) the water in the tube isn’t completely colorless. So my CC is at least 4.0??!!

I would like to SLAM my pool. My CYA is close to 0 and FC is 1.8. What level of shock should I be on ? My pool is an indoor SWG pool.

Thanks
Joanne
 
Re: FAS-DPD kit and Slam questions

Hello Joanne! :wave: Here in the states we tend to do things a bit different for public-type pools because of specific regulations. Not sure if you have those issues there. So please keep that in mind as I provide you with some possible actions to take. Also, since you have an indoor pool, they also have some unique issues to consider. So I'll try to answer your questions with those things in mind:
1 - Yes, colorless, then record your FC (or CC) right away. If you let the solution sit it will begin to change to pink again. Disregard that.
2 - Your math is correct (4.0). Sounds like you have some water issues and the SLAM Process is probably a good decision.

To perform a SLAM Process, we take our current CYA and go to the [FC/CYA][/FC/CYA] to find the corresponding FC SLAM/Shock level. In your case, you show next to no CYA. For our indoor pools, we typically advise about 20 ppm of CYA. The CYA can be lower because indoor pools typically receive no sunlight, so you don't need much CYA (stabilizer) like an outdoor pool. Also note that a pool with little to no CYA means the available free chlorine (FC) will be quite harsh on swimmers, swimsuits, etc. So you might consider increasing the CYA to "20". From there, you can increase the FC to "10" which is an adequate SLAM/Shock level to perform that SLAM Process.

Make sure before increasing the FC to that higher (10) level, you first add the stabilizer AND adjust your pH down to about 7.2. From there, you would maintain the SLAM level (10) until you pass all 3 SLAM Process criteria. Make sure to read all the details of the SLAM Process page to ensure success.

Joanne, if you have any concerns about performing a SLAM for your indoor pool based on local restrictions or the fact it is used as a swim school, you might need to discuss your options with local authorities. I hope that helps get you going. Let us know if you have any other questions.
 
Re: FAS-DPD kit and Slam questions

Note that Joanne said that she cannot obtain CYA in Malaysia.

Joanne, i do not know what the lowest FC level for CYA 0 will clear your CC. A FC level of 10 will work. But without CYA I would not let anyone in the pool until the FC drops below 3. That could take some time.

This forums methods are not setup to deal with CYA 0 pools.
 
Joanne, I merged this new "FAS-DPD kit and Slam questions" thread with your previous thread since they all seem to be related to the same issue. It's best we keep all the notes and input together. I didn't realize you had another existing discussion before adding my comments. You have plenty of folks helping you already, so by keeping all of this together it should help. Good luck!
 
The only chlorine I have which is supplied by my pool guy is 65% cal hypo. I put 2 kg in today to achieve a SLAM of 12 (I got that from the pool calculator app). Will do the FAS DPD test again tomorrow morning and report it here.

The only thing chemicals we put in are soda ash and salt and muriatic acid (hardly ever) and we also have chlorine neutraliser. I don't think we can get much more Chemicals than these.

My pool is clear but a green tint which I suspect is from copper in the water from old rusty pipes. We have installed a simple water filter last week for the pool and the filter cartridge turned brown in 15 minutes
 

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Joanne, you've had quite a few folks helping you, so I'm going to step-back and let those folks continue to help. I'll just leave you with a few very basic comments and let the others build on what you've done so far:
- Remember that in an indoor pool with no CYA, the chlorine gets strong very fast. There's nothing to buffer it.
- You mentioned you added cal-hypo for an FC of 12. I suspect that won't last long and the FC will drop. Cal-Hypo is not the best product for a SLAM Process and it's a bit more difficult to dose accurately and consistently. But as you noted, liquid chlorine (regular bleach) may be tough to get there. Also remember that with continual use of Cal-Hypo, your pool's CH level should climb.
- While the key to an effective SLAM is "maintaining" that SLAM FC level, I wouldn't recommend maintaining that elevated FC level with no CYA registering at all. It's just too strong. If you can't get any stabilizer, we may have to ask some experts to chime-in with their opinion on what may be your best course of action.
- A higher FC level (especially with no stabilizer) will aggravate any metals in the water. Copper already? ... perhaps. Maybe iron? Either metal in high enough form is troublesome and the only way to remove it is by water exchange. Copper typically comes from pipes and/or algaecide products. Iron can be from some hardware and/or well water.

I hope things go well for you. Feel free to back to this thread and use it as much as you need to. Good luck!
 
Thanks for all that info Pat.

I only managed to test it again this morning 14 hours after adding the 2kg of chlorine.

FC is 1.5 and CC is 1.0 and water is blue for the first time in 2 months !

I can only add more chlorine after the classes this afternoon and from the calculator I should add 1.4 kg.

No doubt I am not Slamming it the proper way as I should be testing and adding chlorine every 2-3 hours from what I read.
 
No doubt I am not Slamming it the proper way as I should be testing and adding chlorine every 2-3 hours from what I read.
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That is correct, but we understand you are in a unique situation. Do the best you can. Read-up on all the TFP references (many in my sig below) and hopefully you will get the better hand over there.
 
What Maddie said. Since you are doing a SLAM around the swim lessons you should test and dose as soon as the last person is out. THEN test again 30 later to see if you hit the goal level. Do this until you go to bed for the night. Yeah it will eat up your evening but it will help clear up that pool.
 
Ok tomorrow night I will stay back at my swim school to dose and test after the last swimmer and then test again in 30 minutes. From that result, what should I do next? Use the pool calculator to add more chlorine for shock level of 10?
 

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