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Water Chemistry

This group is for in-depth discussion of pool and spa water chemistry issues at a more technical level suitable to a group for those who are interested.  The emphasis is on matching science and research to real-world observations.

Members: 75
Latest Activity: Feb 12

Discussion Forum

Cyanuric Acid for Indoor Pools? 3 Replies

Started by Howard J Knight. Last reply by Jory Jan 19, 2017.

flocculant 8 Replies

Started by Frank H Dashti. Last reply by Roohollah Akbari Jun 21, 2016.

Phosphates, Phosphate Removers and CuLator™ Metal Remover 57 Replies

Started by Richard A. Falk. Last reply by Richard A. Falk Apr 24, 2013.

Combined Chlorine-what is it exactly? 6 Replies

Started by David Rockwell. Last reply by Richard A. Falk Dec 29, 2012.

The mysterious case of the disappearing CYA 7 Replies

Started by David Rockwell. Last reply by Rick Larson Oct 10, 2012.

Natural Swimming Pools (NSPs) 1 Reply

Started by Richard A. Falk. Last reply by John Pustai Jul 27, 2012.

Enzymes 18 Replies

Started by Richard A. Falk. Last reply by Aaron Heiss Jul 5, 2012.

Oxidation-Reduction Potential (ORP) 6 Replies

Started by Richard A. Falk. Last reply by Richard A. Falk Jun 11, 2012.

Breakpoint Chlorination 4 Replies

Started by Richard A. Falk. Last reply by Richard A. Falk May 29, 2012.

CYA, TA, and the Langelier Index 1 Reply

Started by David Rockwell. Last reply by Richard A. Falk Feb 12, 2012.

SWG and borates 5 Replies

Started by Jeremy Hine. Last reply by Richard A. Falk Dec 4, 2011.

Air Quality Above Pool/Spa Water 3 Replies

Started by Richard A. Falk. Last reply by Richard A. Falk Nov 17, 2011.

Biofilms 28 Replies

Started by Richard A. Falk. Last reply by Richard A. Falk Jul 12, 2011.

Algae 3 Replies

Started by Richard A. Falk. Last reply by Richard A. Falk Jun 9, 2011.

Chlorine Dioxide 2 Replies

Started by Richard A. Falk. Last reply by Richard A. Falk Apr 8, 2011.

Total Dissolved Solids (TDS) 6 Replies

Started by Richard A. Falk. Last reply by Richard A. Falk Mar 19, 2011.

Active Chlorine Level and Disinfection By-Products (DBPs) 14 Replies

Started by Richard A. Falk. Last reply by Richard A. Falk Mar 10, 2011.

Lowering Total Alkalinity (TA) 5 Replies

Started by Richard A. Falk. Last reply by Richard A. Falk Feb 23, 2011.

Total Alkalinity (TA) and pH Effects 1 Reply

Started by Richard A. Falk. Last reply by Richard A. Falk Feb 21, 2011.

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Comment by Al Neumann on April 5, 2011 at 7:50am
Anne,
I hope you don’t mind if I jump in here, but I too was a little confused by your 1st post as to how an apparent bacteria test related to the enzyme discussion unless it was biofilm related, and I don’t think that was really discussed. I’m assuming from this post that this is a hotel facility and the issue is with the spa, as you mentioned the 30-minute turnover rate.

When we run into this problem, and all the apparent items seem to be in check, then the issue is often related to operator error in the sampling technique by contamination and or taking the sample to soon after heavy usage. If they are taking the sample first thing Monday morning, and had a heavy weekend of usage, then shocking the spa Sunday night would help. Are they taking the sample from the surface of the spa, or are they going down deeper. The surface water is the dirtiest.

Another area of chronic re-infection to focus on is biofilm related, and the skimmers are notorious for having pseudomonas just above the water line inside the skimmers and along the wall tile line.

However, the most likely cause for re-infections are filter related biofilms that occasionally break off and re-infect the pool. It may be time for a sand change, or at least open up the filter and remove and replace the 1st couple of inches of sand. Then shock the filter with a gallon of bleach, let sit over night, and then drain it, or heavy shock the whole spa, and drain it. Enzymes will help with the filter, but it takes time. Filter flushes work well, but changing sand is sometimes easiest and most cost effective. This is also a reason why I mentioned technique in taking the sample. They have to take the sample from the main body of water, and not the controller’s sensors flow cell, as its source water is usually coming from just after the filter.

What are they using for chlorine, liquid or Cal Hypo? What ORP are they maintaining? What combined are they running? How often do they drain the spa?

Hope this helps.
Comment by Ann Klute on April 5, 2011 at 6:34am

Pool/Spa samples are submitted weekly for bacteriological sampling.  This particular facility has failed 4 times out of 11 weeks so far this year.  I say he seems to be doing everything correctly as far as cleaning, shocking, maintaining chlorine, ph, alkalinity and hardness all within recommended ranges.  They take readings three times a day.  Turnover is within 30 minutes.  Reagents are new.  Hopefully he is taking the sample correctly.  Those are the usual items that I go over with the CPO's when they are having problems.

Comment by Richard A. Falk on April 4, 2011 at 7:38pm
Ann, can you please be more specific about how the water samples submitted to your laboratory are failing?  Are you talking about bacteriological testing, disinfection by-products (chloramines, THMs, etc.) or something else?  When you say they seem to be doing everything right, do you mean water chemistry parameters are within code limits?
Comment by Kevin Woodhurst on April 4, 2011 at 6:58am
What a great group and discussions... Thanks Richard...
Comment by Ann Klute on April 4, 2011 at 6:48am
Thank you for this discussion.  We have had people continually fail water samples submitted to our laboratory.  Since we also inspect the pools and spas we tried to figure out what could be the problem.  They seemed to be doing everything right and yet continued to fail their samples.  I will forward on the information to their CPO and keep this info handy for our newsletter.  Looking forward to more great info.  Thank you.
Comment by Richard A. Falk on April 4, 2011 at 12:32am

I've added a discussion topic on enzymes as a placeholder for now, but will have to get back to it to fill in more info.

 

Some enzymes are more delicate than others.  Many of the ones used in pools will last up to a week, though it really depends on the enzyme and the chlorine level so will vary by product/manufacturer.  Enzymes should last a lot longer in pools with CYA than in pools without CYA due to the differing active chlorine levels though exposure to UV is another factor that might shorten enzyme effectiveness.

 

DBPs can cause respiratory and ocular irritation and potentially increase long-term cancer risk so in that sense they can be RWIs though usually that term is reserved for pathogens (bacteria, viruses, protozoa, etc), not chemicals.  Would way out-of-balance pH that irritated the eyes be an RWI according to him?  Consider the source of information -- this teacher isn't always accurate.

Comment by David Rockwell on April 3, 2011 at 11:03pm
BTW, the teacher classified DPBs as an RWI. Technically they could be considered a source of RWIs...I guess.
Comment by David Rockwell on April 3, 2011 at 10:59pm

Are we ready for a thread on enzymes?

My question is that I have always envisioned that enzymes are relatively "delicate" in that they are easily destroyed or their effectiveness reduced in the presence of a strong oxidizer like ozone, high chlorine as in shocking the pool, or even high temperature as in a spa. In view of that it would seem that they would be better used as a preventive measure as opposed to a corective one. I'd like to repost a link that Al gave us regarding "designer oxidizers" like Truox. http://ppoa.org/?p=282. (Hope that worked). If a service guy comes up on a green pool, keeping the chlorine low enough to allow the enzymes to work seems counterproductive. Or are enzymes not as fragile as I imagine?

 

Comment by Al Neumann on April 3, 2011 at 8:31pm

Thanks Richard. I was thinking DPB's, but put down RWI's instead. I was also referring to the clarifier and/or the PRS System product, which encapsulates the oil in a chlorinated environment.

I have a tendency to agree with you that all in all, when all is said and done, that the enzymes would end up having more of a beneficial effect, as that is what I have seen when we do end up using them.

It's just that David's and your comments got me to thinking...you know how that is.

Thanks again.

Comment by Lester Eric Brehm on April 3, 2011 at 8:28pm
Richard, I really appreciate your input especially because you have no other motive but to find the facts and not to sell a product. Also because your not funded buy by  a major chemical manufacturer.
 

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