Sudden cloudy water, why?!?!

[ChiknNutz]

A bit of history on this spa. Bought it used, but in really great shape. First filled it and balanced chemicals. Seemed to have a hard time keeping enough chlorine in it and got to looking at the chemicals the previous owner used...biguanides. I then did a full spa decontamination (per instructions I've found referenced on here). Refilled and balanced, using full BBB method. Did the spa refill on May 20th and water has been crystal clear since, no issues. We use it quite a bit, nearly daily and I am very diligent about testing and balancing. My typical routine is to add about 4 oz. bleach when I get home from work, use the tub and then add 4 or 5 more oz after use. I last added chlorine and checked balance on June 6th. Today, June 8th, I open and am horrified to find really cloudy water AND it kinda stinks. I am assuming this must be organic contamination of some kinda, but am at a loss as to why or what.

Readings today AFTER adding 6 oz. of 6% bleach at about 6 PM, readings taken at 9:30 PM:

FC: 3.0
CC: 1.5
pH: 7.4
CH: 130 (reading taken on 6/6 and have since added 3 more oz. of CH+)
TA: 60 (reading taken on 6/3)
Temp: 101 F

FYI, the filter is a 2-stage and was in good shape on last refill, but I think we have a lot of iron in the water (well water) and the filter almost immediately turned rusty colored. Tonight, I replaced both with brand new ones, so will see if that helps at all. Thanks for any assistance offered!

 

[teapot]

Time to go back to school..................
pool-school/shocking_your_pool

 

[ChiknNutz]

Took it to shock level for about 24 hours and seems to be back to normal. With the pool, I rarely have to shock, guess it's a different story with a spa (weekly shock it seems is typical).

 

[chem geek]

If you are using enough chlorine, then you normally don't need to shock the spa (except to catch up, as with this time). I assume you used Dichlor initially (or pure CYA) to get the CYA level to around 30 ppm or so and then you switched to using bleach, correct? In a hot (104ºF) spa, the amount of oxidizer needed to handle bather waste from every person-hour of soaking is 3-1/2 teaspoons of Dichlor or 5 fluid ounces of 6% bleach or 7 teaspoons of non-chlorine shock (43% MPS). It's possible you aren't using enough chlorine though 8-9 ounces should handle 1.6-1.8 person-hours of soaking (so 2 people for 45-55 minutes). Nevertheless, if you are adding enough chlorine, you should have at least 1-2 ppm FC measurable before your soak (before adding any chlorine, of course).

Of course, it's possible someone urinated in the spa which would use up the chlorine rather quickly.

 

[ChiknNutz]

Yes, used Dichlor to get the CYA technically to around 30, though my test results don't confirm that (other posts on the subject). Now using 6% bleach. The kids were in the spa over the course of this issue, so it is possible that they pee'd in there, regardless of how many times we tell them not to B-/

I've seen you reference these figures elsewhere about the typical FC requirement...thanks for that. Question...what FC level should I shoot for right before a soak? Should I try to hit somewhere around 6 or so to help account for the FC reduction during the soak? Or, should I just wait until AFTER the soak to add more chlorine? So, either a little before and a little after, or a lot after?

 

[chem geek]

Question...what FC level should I shoot for right before a soak? Should I try to hit somewhere around 6 or so to help account for the FC reduction during the soak? Or, should I just wait until AFTER the soak to add more chlorine? So, either a little before and a little after, or a lot after?

Well, this is really up to you. Most people don't like smelling chloramines or even chlorine during their soak so tend to target 1-2 ppm FC before their soak. At that level, the monochloramine that forms from the ammonia in sweat and urine isn't noticeable since it's roughly at the same level as that found in chloraminated tap water.

A few people want to ensure rapid disinfection during their soak, similar to that in commercial/public pools and spas. In this case, you want to have a high enough FC such that there is still measurable FC right after the soak. Though the ammonia from sweat and urine will react in a minute or less with the chlorine, the urea is slower to react possibly taking some number of hours. So having the FC at the start of the soak set to around 1/4th to 1/3rd the total needed to handle bather load would probably be enough to last through an hour of soaking. Of course, the real way to tell these things is to test the FC right after a soak and just set the FC level high enough at the start of the soak to still have 1-2 ppm FC at the end of a soak.

Generally speaking, unless you are going to be soaking with strangers, having 1-2 ppm FC at the start of the soak should be fine. The bacteria you shed still get slowly killed by monochloramine (enough to inhibit uncontrolled bacterial growth) and they don't have time to reproduce in large numbers. It's the uncontrolled bacterial growth that you could ingest and overwhelm your immune system that you want to avoid which is why you need chlorine in the water during the long time between soaks. Commercial/public pools and spas have a faster kill standard in order to avoid person-to-person transmission of disease, but this is less of an issue in residential pools and spas. So having a brief period of low disinfection rates is not as serious as it would be for commercial/public pools where one infected person could infect dozens if not hundreds of people.

Now, that said, no manufacturer can say this since it would be a violation of the FIFRA rules since the EPA regulates what can be said. You are supposed to use registered pesticide products, such as the disinfectants used in pools and spas, according to label directions. Specifically, there is wording: "It is a violation of federal law to use this product inconsistent with its labeling." See this link for more info. In practice, the government doesn't go after people who could potentially harm themselves by misuse of such pesticide products -- the language is mostly for protection of others as with commercial/public situations and for protection of the environment. So not maintaining proper levels in your own pool or spa is technically a violation of law, but no one is going to go after you for that (though someone else using your spa could sue you and refer to the law, though I've never heard of such a case that referenced FIFRA in this situation), but if you improperly dispose of the chemical then that is something that could get you into trouble.