Interesting Site For Those With ORP and Acid Feeders

smallpooldad

Well-known member
Aug 6, 2008
429
Honolulu
Anyone like to comment, his idea seem reasonable for those of us with ORP controllers and acid feeders in a both a non salt water system and a salt water system, particuarly for older pools.

I know it deviates from the standard CYA method but is it worth considering?

He feels that this is suitable for residential pools with a moderate load (not commercial where one would have to feed the pool all day), targeting an ORP of 650 by raising the ORP at night presumably to above 650, my guess is 700+, by running the pump only when it is dark or starting in the late afternoon. Trial and error as regards to feed %, power, and pump running time until one acheives the desired effect depending on pool size of a minimum CYA of 650 before the pump starts up. He runs his 26,000 gal pool from 4pm to midnight.

If one had a pool party one could always switch it on prior, during, and after to neutralize the load, or add liquid chlorine.

The only down side I can see if that if your cell failed you would get an algae bloom but that would happen with a CYA pool as well. So one still needs to make sure ones unit is working daily. But are there any other side effects I am not aware off?

http://www.truetex.com/poolcontrol.htm
 

JasonLion

TFP Expert
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May 7, 2007
37,880
Silver Spring, MD
His system is entertaining and has some very interesting engineering, but his analysis of CYA is deeply flawed. He bases a fair bit of his understanding on a paper by Kent Williams which contains several errors and misleading statements, and he then extrapolates from those mistakes to make further mistakes/misunderstandings of his own. Nearly everything he says about CYA is wrong in one way or another.

Using zero CYA, as he does, is possible, however it requires using significantly more chlorine than you would use with CYA, tends to increase hair damage and fading of bathing suits compared to pools using CYA, and is more trouble prone.

ORP automation isn't really desirable in an outdoor residential pool. ORP sensors present challenges, both inherent and as a practical mater, that make them more work to use and less reliable than simple percentage based automation common on most SWGs.

His ideas about astronomic timing are very interesting, though I don't think he goes far enough. Day length is only one aspect of chlorine demand. Others, such as water temperature are at least as important. Systems like the AutoPilot temperature compensation system and the TightWatt timers both have essentially the same advantages as his astronomic system, since all three depend on factors that correlate fairly well with UV chlorine usage. Some more advanced system that took several indicators into account could be even better.
 

smallpooldad

Well-known member
Aug 6, 2008
429
Honolulu
Jason,

Interesting comments, well I think I will continue with my normal CYA set up once I have resolved my current issues. But I do have a few questions when you have time as this is obviously not as urgent as helping someone having an algae breakout.

Question 1: Why is it more trouble prone?

Question 2: From what you have wriiten it seems that this type of system is ok for indoor pools. Am I correct in that assumption.

Question 3: What systems are even more advanced than Pool Pilot etc?

Thank you for the quivk reply.
 

JasonLion

TFP Expert
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LifeTime Supporter
May 7, 2007
37,880
Silver Spring, MD
1) With CYA at zero, FC can fall to zero in a couple of hours. With CYA in the water it would tend to take a couple of days before FC fell to zero. Those extra days give you more time to react before algae gets going.

2) Indoor pools and commercial pools experience dramatic changes in chlorine demand with varying bather load. In those situations simple percentage based control is useless, and ORP is worth considering despite it's disadvantages.

3) I said "could be" :) I don't think that anyone actually sells a system that is more advanced than the AutoPilot Total Control or Hayward Sense and Dispense for residential use.
 

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
12,082
San Rafael, CA USA
Remember that the active chlorine level in pools maintained with the FC/CYA ratios recommended on this forum are roughly equivalent to having around 0.1 ppm FC with no CYA. It is very difficult to maintain such a low FC level everywhere in the pool. The smallest chlorine demand can consume that chlorine locally so the sanitation and oxidation will be very inconsistent. The usual way to compensate for this in indoor pools is to have a higher FC level, usually around 1 ppm FC or more, but that is an active chlorine level that is over 10 times higher so oxidizes swimsuits, skin and hair that much faster and probably produces 10 times the amount of very irritating and volatile nitrogen trichloride when ammonia (and probably urea) are oxidized.

Using CYA as a chlorine buffer lets one have a fairly low active chlorine level that is still very sufficient for killing pathogens, preventing algae growth, and oxidizing bather waste, but also has a large chlorine reserve so that you don't run out locally.
 
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