Pool water cloudy with light on clear othwerwise

[HouTX]

1. The pool has had very little to no usage until the last few days
2. Torrential rainfalls in Houston during the last week
3. Bather load has increased significantly over the last few days

The pool water looks clear during the day but at night with the light on, the pool water looks extremely cloudy with suspended fine particles (right in front of the light). Here are my current readings, what am I doing wrong ?

Filter run time 1 hour in the morning + 4 hours afternoon into evening, SWG 55%
FC 3
CC .5
pH 7.5
TA 75
CYA 50
CH 350

 

[Richard320]

Everyone has floaters. If you seal the pool so no dust can blow in and keep people out so there's no dead skin or hair coming off, and then filter it nonstop for a day, you could probably eliminate them all. But that's no fun.

 

[Azgirl71]

Your FC needs to be min of 4 and a target of 6 for your CYA of 50. Is there a reason your CYA is 50 since you have a SWG?

As Richard said run the filter 24/7

 

[HouTX]

I have added 8 lbs. of CYA over the last few months to get the reading at 50. I thought I was at 70 for a while but I am now attributing that to rookie test errors. I am confused however, are you saying it is normal to see cloudy water and particles in the direct beam of the pool light at night ? Should I still be running filter 24/7 and if so for how long ?

My FC level was at 6 and I thought that was overkill for my CYA level (based on the chart on this forum) so I reduced run time/SWG% in the last few days and just measured it at 3ppm. In hindsight that was not a good idea as the teenagers have started using the pool now along with their friends. I am planning on getting the CYA up to 70 in the near future.

 

[Richard320]

Even crystal clear water will have floaters visible in the pool light at night. I have a bunch. It's just a fact of life. It doesn't prevent me from being able to tell that the screws on the main drain cover are Phillips head. It's normal. I keep my pool clear with only 3 hours filtering a day, plus whatever it gets when I vacuum.

 

[HouTX]

The reason I am avoiding increasing CYA further (& pump run time= aeration) is that I want to minimize SWG run time. I have a perpetual rise in pH and adding MA 2-3 times per week to keep pH below 8 (I hate handling the stuff so I am trying to minimize its usage). I found a chart posted by ChemGeek a while back, and was going to shoot for a FC of 4 with CYA of 50.

 

[Richard320]

The reason I am avoiding increasing CYA further (& pump run time= aeration) is that I want to minimize SWG run time. I have a perpetual rise in pH and adding MA 2-3 times per week to keep pH below 8 (I hate handling the stuff so I am trying to minimize its usage). I found a chart posted by ChemGeek a while back, and was going to shoot for a FC of 4 with CYA of 50.

Actually, raising the CYA will cause you to lose less FC every day and let you run the SWG less. The minimum level is higher, but the amount you lose and have to replenish every day will go down. If your pool is in full sun all day, it could be substantial.

 

[pooldv]

Lower your TA to 60 and add borates to help with the PH. Here's how:
Pool School - Lower Total Alkalinity
Borates - Why and How

As for dust sized particles floating in your pool light, it is normal. My pool water is spankin clear, I don't see how it could be more clear, and there is itty bitty stuff floating in it. See pics in my build thread in sig.

 

[HouTX]

I have increased CYA to 70 as you suggested, and raised my SWG to 100% for 5 hours runtime and the pool is maintaining 4.5 FC. I would like to reduce the SWG run time to help manage pH better. It is very apparent from my limited experience that the SWG is excellent at maintaining FC, but not raising it substantially at a given pump run time. I am thinking of adding bleach to raise the FC to 6 and then gradually lowering SWG % to maintain water in the 4-6 FC range. Any flaws in this plan ? The dramatic change in SWG% was necessary to account for the increased CYA and the fact that the daily temp has jumped from cloudy mild 80's to sunny mid 90's at the time I raised my CYA. Pool gets about 8-10 hours of direct sunlight.

 

[chem geek]

The reason I am avoiding increasing CYA further (& pump run time= aeration) is that I want to minimize SWG run time. I have a perpetual rise in pH and adding MA 2-3 times per week to keep pH below 8 (I hate handling the stuff so I am trying to minimize its usage). I found a chart posted by ChemGeek a while back, and was going to shoot for a FC of 4 with CYA of 50.

I don't know what chart you looked at because the chlorine/CYA chart doesn't say anything about how quickly chlorine is lost due to sunlight. The chart in this post makes it very clear that higher CYA levels even with proportionally higher FC levels (so the same active chlorine level) has lower absolute FC loss. We don't know why this is for sure but suspect there is a non-linear CYA shielding effect of UV from sunlight protecting chlorine (and chlorine bound to CYA) at lower depths.

See the Pool School article Water Balance for SWGs where a lower TA, higher CYA, and use of 50 ppm Borates result in a slower pH rise over time and lower acid usage. The higher CYA in particular is what lets you turn down your SWG % ontime.

 

[HouTX]

That post was not about chlorine loss, but the absolute FC / CYA chart that you had posted. Lowering the TA to 75 has helped maintain pH in the mid to upper 7's thus far with weekly additions of MA (as opposed to multiple additions/week). I am not going to introduce Borates into the pool unless necessary (to stabilize pH). Right now I am trying to lower SWG% if I can, by augmenting the FC with chlorine and tweaking the % to keep it in the 4-6 range. So yes, now I will need to determine chlorine loss in my setting and your chart may come handy.