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Thread: .5 CC and OCLT Test Question...

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    .5 CC and OCLT Test Question...

    The other night one of the kid swimmers in my pool noticed the pool light had some gunk on it. I started to investigate things further and noticed that the rock holding down my skimmer basket also was slimy. The pool skimmer itself was also very slimy feeling.

    My water has been pretty clear and my numbers have been good all season long. I have never measure and more or any less than .5 combined chlorine. I know that .5 can mean trouble depending on whether or not the water is clear.

    I would say my water is not up to par. While it is clear, it isn't crystal clear like it normally is. So I have started testing more vigorously. I have learned that my CYA has gone way down. I could barely get the dot to disappear giving me a reading of approx 15.

    I added stabilizer yesterday. I have been adding bleach to get it to shock level but the water is still not crystal clear. It has a slight opaque cast to it. So it seems to me that I need to learn why my water is unclear.

    The most likely culprit is something is growing in the pool. So now I am a bit unclear on where to turn. Should I start the shock process again or should I wait for more of the stabilizer to disolve? Also when I do start the shock process again and perform the OCLT test, do I need to keep the filter running over night?

    Here are my current numbers:
    FC 6.5
    CC .5
    TA 90
    pH 7.5
    CYA 15

    (these tests were performed yesterday, cya could have risen some but it takes awhile)
    10,000 gallon
    Viking Freeform Fiberglass Inground Pool. FNS Plus DE Filter Pentair Challenger .75hp pump

    NC KANSAS44

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    Mod Squad woodyp's Avatar
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    Re: .5 CC and OCLT Test Question...

    I'd make sure and brush the whole pool down to break that slimy feeling "film". Maintain your shock level for the level of CYA you just brought it up to.
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    Richard320's Avatar
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    Re: .5 CC and OCLT Test Question...

    Brush and bleach. Don't neglect things like ladder rungs and behind the pool light.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
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    BoDarville's Avatar
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    Re: .5 CC and OCLT Test Question...

    If you have algae, you should shock the pool.

    Do you recall how much stabilizer you added? That will determine your shock FC target. The current low CYA may have resulted in much of the FC being lost to sunlight. That opens the door for algae to set up shop. The fact that your water isn't crystal clear is another sign that algae is present, but has not manifested itself with a full-scale bloom yet.

    Normally, I would suggest that you lower pH to around 7.2 before beginning the shock process. However, since you just added stabilizer, that will lower pH a bit depending on how much you added. So, in this case, I would not take further steps to lower pH .

    The filter should be running 24/7 while going through the shock process. Be sure to check filter pressure frequently as you may need to clean/backwash more frequently than normal.
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    Re: .5 CC and OCLT Test Question...

    OK. So I am a couple days into this now. I have been trying to maintain shock level but it has dropped below a couple times before I could catch it.Regardless, I have dumped about 6 gallons of bleach in the last 2 days.

    The water still appears hazy, not crystal clear. I added about 10 oz of stabilizer the other day and current cya is 25. I just added 10 more ounces.

    Current numbers:

    pH 7.3 (added some borax to compensate. )
    TA 90
    CC .5
    FC 12 (added another gallon of bleach)


    I have been running my DE filter non stop. The pressure on it has actually dropped from 17 to 15lbs. What would cause this? I am starting to wonder whether I actually have a chemical problem or a filter problem?

    Is it possible that my filter is simply not filtering as well and therefore the hazy water? I will continue shock process but am starting to wonder if I will ever get there. Am I just dumping $ and bleach down the drain?
    10,000 gallon
    Viking Freeform Fiberglass Inground Pool. FNS Plus DE Filter Pentair Challenger .75hp pump

    NC KANSAS44

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    Re: .5 CC and OCLT Test Question...

    You didn't post your Calcium Hardness (CH) number, but I assume it's not extraordinarily high. If it was, then that could cause cloudiness, though usually only if your pH was higher (given your TA which is not unusually high).

    It does seem like your filter isn't capturing the particles in the pool, for whatever reason. Then, there's Ben's 100 Reasons for Cloudy Swimming Pool Water.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
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    linen's Avatar
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    Re: .5 CC and OCLT Test Question...

    To determine if you still have something being sanitized/oxidized by chlorine I would do the OCLT. If that passes, and your CC is <0.5, then I would look at the filter.
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

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    Re: .5 CC and OCLT Test Question...

    I will try and run an OCLT test tonight if it doesn't rain. Water looks better this morning but still not perfect. I should note that I wouldn't really describe my water as "cloudy." I would describe it more as "hazy". One might ask, "what is the difference?"

    I guess in my mind I would say, that it is like looking through a pair of eyeglass lenses that are not perfectly clean. There is a bit of haze to the appearance as if there is thin layer of oily substance on the lenses.

    As far as something being wrong with the DE filter, I am led to wonder.....what could it be? I would think if there was a leak and/or hole in something I would be getting DE in the pool. I don't see any. If there wasn't enough DE I would think the filter pressure would be very high. ??? My filter pressure is basically where it was with new DE.

    One issue I haven't mentioned is that I have been wondering if the pipe dope I used to fix a leaky plug in the return line might have been leaching out into the pool water. Last night I removed the plug (circled in left side of picture) and cleaned as much of the pipe dope off as possible. Could this be making the water hazy?

    10,000 gallon
    Viking Freeform Fiberglass Inground Pool. FNS Plus DE Filter Pentair Challenger .75hp pump

    NC KANSAS44

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    harleysilo's Avatar
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    Re: .5 CC and OCLT Test Question...

    Not sure about the pipe dope, my experience with that is water doesn't affect it (remove it) meaning i would doubt it would get removed from where you put it and be getting into the water.

    When was the last time you opened up your DE filter and really cleaned it? Might be something you should consider. I'm sure you've read to only add 80% of the required amount of DE back into your filter after a backwash as the backwash doesn't remove it all. We had a recent thread that showed the problem of constantly over adding and not cleaning. My DE filter was NASTY after 1 year of no breakdown and 2 back washes. However i was noticing hazy or cloudy water.....
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    Richard320's Avatar
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    Re: .5 CC and OCLT Test Question...

    Quote Originally Posted by Thinkly
    ...
    As far as something being wrong with the DE filter, I am led to wonder.....what could it be? I would think if there was a leak and/or hole in something I would be getting DE in the pool. I don't see any. If there wasn't enough DE I would think the filter pressure would be very high. ???
    ...
    Coating the grids with DE should raise the pressure slightly; maybe not enough to see on the gauge, but every setup is unique. If you're low on DE, it will leave bald spots on the grids where water can get through without being filtered, and the pressure will also be slightly lower because there's less resistance to flow.

    Forgive me for not hunting through your post history to check, but when's the last time you broke down the filter and really cleaned it and did a full recharge?

    It's also a long shot, but is it possible the multiport valve is letting some water bypass the filter?
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    Re: .5 CC and OCLT Test Question...

    I opened the pool the first week of April I believe. At that time I removed all grids, inspected, cleaned and reassembled. I have had to backwash it once so far and that was right after opening and removing all of the winter's dirt etc. Since then the pressure rose from 15 (normal starting) to 17 lbs. Then in the last couple of days (after running continually for days) it went down to close to 15-16 again which is where it is now.

    How would I know if the multiport is letting some water bypass the filter?
    10,000 gallon
    Viking Freeform Fiberglass Inground Pool. FNS Plus DE Filter Pentair Challenger .75hp pump

    NC KANSAS44

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    Richard320's Avatar
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    Re: .5 CC and OCLT Test Question...

    Quote Originally Posted by Thinkly
    I opened the pool the first week of April I believe. At that time I removed all grids, inspected, cleaned and reassembled. I have had to backwash it once so far and that was right after opening and removing all of the winter's dirt etc. Since then the pressure rose from 15 (normal starting) to 17 lbs. Then in the last couple of days (after running continually for days) it went down to close to 15-16 again which is where it is now.

    How would I know if the multiport is letting some water bypass the filter?
    Typically, you see water dribbling out the waste port if the gasket isn't sealing.

    My filter pressure varies a lot depending on where I have the suction and return valves set. Be sure you aren't comparing pressures in different modes.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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