Recent content by Tom ONeill

"wayner", The rate constants for photolysis of exposed HOCL/OCl- are affected only by the intensity of the UV radiation applied (received). UV radiation is a fairly fixed fraction of total solar intensity, and the amount received is also affected by atmospheric screening and altitude over sea...

Thank you JoyfulNoise for your input. It's very interesting that you can run consistently well at "FC/CYA ratio of 0.025-0.03 with 100ppm CYA". At what pH are you generally running? As an aside: I was recently talking with a very senior pool technician here in Tucson who said they had one...

Thank you "newdude". I hadn't seen this new chart guidance for SWCG pools. An improvement.

A couple of fundamental examples at 50 ppm CYA if I may: Chlorine loss to photolysis is the Big Bad Wolf. At 3.75 FC/50CYA, 0.075 Ratio, photolysis ppm loss is 1.56 times that of 2.5 FC/50 CYA 0.05 Ratio. At 5 FC/50 CYA, 0.1 Ratio, photolysis ppm loss is 2.16 times that of 2.5 FC/50 CYA 0.05...

Interesting that Richard recommended a FC/CYA ratio of 0.1. And I agree, as it's much better at maintaining sufficient disinfection of pathogens and also for better control against any algae growth. What stumps me is why, after all these past years, everyone is saying you really only need a 0.05...

Thank you for the detailed clarification.

Clarification: 4 FC/50 CYA, .08 Ratio vs. 2 FC/25 CYA, .08 Ratio. The PPM Chlorine not bound to CYA is Identical. At the same Ratio, all combinations of FC/CYA that have the same Ratio will have essentially the same unbound Chlorine level.

As a p.s., Richard's info from 2007 is actually more accurate than the results today from Pool Equations. (2014 last update, I believe). In the latter rendition Richard is calculating the loss rate against the Entirety of chlorine, not just what's exposed to photolysis. The entirety Is Not...

Thanks "mgtfp" for the reference to Richard's Pool Equations spreadsheet. I have been using it for quite a long time. It's a very comprehensive piece of work. I've used it often to "game" alternative operating profiles and really appreciate the ability to drill down to the fine details when...

I have noticed that for some years now it has been recommended for Saltwater Generator Chlorine (SWG) pools that the Chlorine/Cyanuric Acid (FC/CYA) ratio should be a minimum of .05 with a recommended 70 to 80 PPM CYA level, vs. the traditional .075 FC/CYA ratio. For the moment, set aside the...

Does anyone know of a reliable first-order or pseudo-first-order rate constant (or equivalent half-life time, from which I can get the rate constant) for the kinetic decay of aqueous chlorine in water (without photolysis or other reactions)? I have done a lot of web searching, read lots of...

A p.s.: I also appreciated the graphic you provided on the half-life curves at various levels of CyA. I had, however, already seen that when I first started "caring" about our pools. If you are running any chlorine into the pool at a relatively constant rate by any means (Trichlor, SWCG...

I appreciate your information on the CSI/LSI. Provides more detail on how it came about and how it applies. Thanks. After the county shut our pools down, and I then took over, we drained the pools entirely, cleaned them, refilled with fresh water and started over. We added granular Cyanuric...

I leave the measuring of grass heights and weed counting to the owners. Most of them could do with more outdoor exercise anyway. I just wish they would pick up after their dogs. We are currently running both pools at 50 ppm CyA +/- 2 ppm and 4 ppm FC, +/- 0.3 ppm through the day (it drifts, of...

Once again, Oops. Correction: "Now ask: What percentage (ratio) of Free Chlorine will be destroyed by the very same solar UV on December 21 (solstice) at noon? Ans: The percentage (ratio) of the unbound chlorine (HOCL/OCl-)." Should end: "Some percentage of the percentage (ratio) of the unbound...