Clear pool sucking up the chlorine

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Ryno98

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Dec 27, 2013
92
East Texas
My 1 month old pool has been crystal clear ever since the plaster dust went away. I have absolutely LOVED this site and treated it as pool gospel when it comes to testing (TF100) and using PoolMath to adjust. Everything has been great but it seems like I'm going through considerably more chlorine than I would expect. Cloudy days will consume approx. 3 ppm FC, but bright sunny days are eating 6-6.5 ppm FC!

My latest test results:

pH 7.8 (pool pretty much lives here despite 16 oz MA every night)
FC 3.5 (end of the day, prior to re-dosing. Bump up to 9.5 or 10 each night to account for daytime loss)
CC 0
CYA 30-35 (I think -- standard newbie lack of confidence on this test)
TA 70
CH 75 (stays persistently low -- might have to supplement this against all recommendations so far to keep CSI above -0.6 at lower pH - if I ever get there)

At least it's been consistent for the last 2 weeks. I have done a couple of overnight chlorine loss tests and passed. Of note, my pump doesn't run at night. I'm not sure if this would cause a false pass in the overnight test or not.
I've considered increasing CYA to 50 or so, but it still just seems like I'm loosing an excessive amount of chlorine, even at my current CYA level.
If it matters, I do have high evaporative loss on hot days as the wind blows pretty good at my house most of the time. I'm replacing about 1/2" per day.

Other than increasing CYA to around 50, should I be concerned about anything else?
 
Definitely bump the CYA up to 50 and see how that goes for you. :goodjob:
 
Back to basics......two things and ONLY two things consume chlorine.....sunlight and organics in your pool. A pool in your climate with 50 CYA will typically lose 2 ppm in a 24 hour period to the sun. If you are losing more than that, there can only be one logical conclusion.

Despite your OCLT results (which I would repeat...I think that's where the error is), there is simply no other factor that can account for your FC loss.
 
Thanks for the advice. I will add CYA to get to 50, then repeat OCLT if losing more than around 2 ppm/sunny day. Unfortunately is is pouring rain all day today so it looks like I will have to wait until tomorrow to get going.
 
Ryno98 said:
My 1 month old pool has been crystal clear ever since the plaster dust went away. I have absolutely LOVED this site and treated it as pool gospel when it comes to testing (TF100) and using PoolMath to adjust. Everything has been great but it seems like I'm going through considerably more chlorine than I would expect. Cloudy days will consume approx. 3 ppm FC, but bright sunny days are eating 6-6.5 ppm FC!

My latest test results:

pH 7.8 (pool pretty much lives here despite 16 oz MA every night)
FC 3.5 (end of the day, prior to re-dosing. Bump up to 9.5 or 10 each night to account for daytime loss)
CC 0
CYA 30-35 (I think -- standard newbie lack of confidence on this test)
TA 70
CH 75 (stays persistently low -- might have to supplement this against all recommendations so far to keep CSI above -0.6 at lower pH - if I ever get there)

At least it's been consistent for the last 2 weeks. I have done a couple of overnight chlorine loss tests and passed. Of note, my pump doesn't run at night. I'm not sure if this would cause a false pass in the overnight test or not.
I've considered increasing CYA to 50 or so, but it still just seems like I'm loosing an excessive amount of chlorine, even at my current CYA level.
If it matters, I do have high evaporative loss on hot days as the wind blows pretty good at my house most of the time. I'm replacing about 1/2" per day.

Other than increasing CYA to around 50, should I be concerned about anything else?
Click to expand...

holy cow! 6 - 6.5 ppm per day! duraleigh is right. repeat that OCLT because something is not right. id retest CYA too. Either you are wrong and you have very little CYA or something is growing in your pool.

on that CYA test, stand with sun at your back when you do the drops to white out the black dot. and this is one test you can do over and over. after you lose the dot, record the result, pour it back into the dispenser and do it again to double check.
 

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jblizzle said:
Add this to your profile so we do not have to keep asking as described HERE .
Click to expand...

Done -- Thanks.

I snuck out during a gap between rain showers this evening to get samples for testing. I lost 3 ppm today (since I added 10% bleach at 8 PM last night) and the weather was completely overcast and raining most of the day. I have more CYA to add but with the pool currently draining into the overflow drain I really don't want to chance it running straight down and out my french drains. Should I just go ahead and start SLAM at this point or wait until I get the CYA confirmed at 50 and run more tests/repeat a OCLT?
 
Update: I got my CYA to 45 (still a little left to dissolve in the sock - that stuff takes forever!) and despite this I STILL lost 6-6.5 FC on a bright sunny day (to further complicate my measurements, however, at least 3 toddlers were swimming on that day). Anyway, I went ahead and jacked my FC up to 18 last night. I had a busy morning and didn't get to check again until about 2 PM and FC had dropped to 7.5! CC <0.5, bright sunny day, clear pool, but still! -- 10.5 ppm loss! I know that you lose FC in the sun as a percentage of FC related to CYA, but this seems like pretty excessive loss for sun so I'm continuing the SLAM process. Jacked the FC back up to 20 and have the rest of the day off to mess with it now and brush the pool. I plan to repeat a OCLT tonight and see if I'm making any progress. I still can't get over the fact that apparently something has been growing in that crystal clear water.
 
Old thread resurrection - I think I finally found my problem! To update - I've been pretty much consistently dealing with intermittent excessive daily chlorine consumption despite having a clear pool and even passing the OCLT several times throughout. My pool features an entire back wall composed of gunite waterfalls - about 40 feet in length. The waterfalls work by the pump filling a basin or weir at the top, then overflowing into several lower basins and over "rock" ledges and things into the pool. The basins have drains plumbed from the bottom of each one leading to inconspicuous openings lower down where they drain into the pool. The drain openings in the basins are by necessity small so that the majority of the water cascades over the lip to create the waterfalls. Because of this I cannot see the inside of the drains. I only run the waterfalls every few days or so (it takes 3 pumps so lots of $$ in electricity). I think that this plus rain water draining and possibly collecting intermittently in the drain/basins has likely led to some level of algae growth inside the drains and away from view. This is also unfortunately not really accessible for any brushing or physical cleaning.

I'm still working on a solution to this problem. I'm considering putting the waterfalls on a timer to run for 20-30 minutes 3x per day, shocking the pool every couple of weeks and circulating through the waterfalls overnight, or maybe just accepting my fate and dumping extra bleach in the pool every day or so to compensate. Since the pool is clear and I never let the FC get below minimum levels, economics really becomes the primary driver for this situation.

Also, to give credit to the TFP forum, this has been discussed in slightly different forms in the past according to my recent search - but to my knowledge nobody has come up with a perfect solution...
 
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