New automation project.

[zephyrbar]

Hi again.

I have been charged with the dubious honor of automating the sanitizer on our small comercial pool. We are located in Guatemala so rules and code are pretty much out the window, but we still like to do things (sort of) properly.

The pool is located within the grounds of a hostel for backpackers and the pool features a swim up bar (hence the need strong sanitization hardware)

I have estimated a bather load of 245 person hours a day over 7am til 7pm and it is a 33,000 gal pool. If we were to have a party that would increase to 400p/h est but this would not happen more than 3-4 times a year.

In order for me to automate the chlorine demand I have been looking at a ppm and ph module made by chemtrol that reads accurate? FC levels and has a relay output for swg or chemical feed. And one feed for ph adjustment. The literature says that the probe is not affected by the cya level but suggests a cya level.

In another post I read about typical chlorine demand per bather hour in a well vs poorly managed pool and have come to the unfortunate conclusion that due to the age range and the addition of a bar in the pool, a lot of them are not going to leave the pool to pee, I am going to need enough punch in the swgs to handle that when necessary.

Another question I now have is after putting some info into the pool calc and the effect of chorine gas on pH. It lowers it so if that is the case the pH would need to be raised by the 2nd chemical feeder, is this correct?

Any help is appreciated,
Chris

 

[jblizzle]

Just want to start off the discussion that we do not recommend the use of ORP sensors for chlorine. They just do not work well for outdoor pools with "higher" CYA levels. With a SWG, you would be better off just dialing in the % output and manually boosting the FC levels for high demand times.

Also, with the very high use and waste, some kind of supplemental oxidation would be a good idea ... like UV or ozone systems.

Why are you asking about chlorine gas? While it would lower the pH, a SWG actually tends to raise the pH.

 

[JasonLion]

The ppm sensors tend to foul fairly easily (especially from metals in the water), and need frequent cleaning.They are also expensive to replace. PH sensors work well as long as they are replaced at least every two years.

Yes, chlorine gas will lower the PH fairly quickly, so you need something to raise PH in the PH control feeder. Have you considered feeding bleach instead of chlorine gas? Bleach uses more storage area and loses strength over time, but it is much safer to handle/work with.

{EDIT}If you mean using a SWG, then the PH will either be stable or go up. You can make it go up by raising the TA a little. ppm chlorine sensors are essentially unusable with a SWG as the salt level required for the SWG will foul the ppm sensor very very quickly.{/EDIT}

 

[zephyrbar]

Ok I probably confused myself , I thought the lbs per day produced by a swg were entered into pool calc as chlorine gas?

I am not talking about an ORP sensor but a true FC sensor that measures the FC from 0.1 to 10ppm. A bit pricey but I cannot rely on any one person here to keep the pool chemistry in check every day. So my thinking was to automate the majority of it. I have read posts about the problems involved in using an ORP with the accuracy problems associated with cya levels and the ph swing. But I found a ppm probe that (supposedly) is not affected by cya levels.

Cheers.

- - - Updated - - -

I had considered bleach and I do get big containers of 10.5% bleach but the have to travel 280kms to get to me!

 

[jblizzle]

That is how the SWGs are spec-ed in the amount of FC they produce, but you are not actually adding chlorine gas that would lower the pH.

Can you provide info (link) to the FC sensor you are talking about?

 

[JasonLion]

ppm chlorine sensors are essentially unusable with a SWG as the salt level required for the SWG will foul the ppm sensor very very quickly.

 

[zephyrbar]

http://www.sbcontrol.com/salt_generators.htm would be the one I was looking at with their 255 or 265 control module. I called their tech support this afternoon and asked a few questions regarding swg, he said pre 2010 there were problems but they work better now.

I read you can clean these and they have a 2 year warranty. It sounded promising. For a commercial pool maybe viable?

Thanks again for any info.
Chris