Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 7 of 7

Thread: Zero chlorine in pool with Intellichlor IC-40, algae growing

  1. Back To Top    #1

    Zero chlorine in pool with Intellichlor IC-40, algae growing

    I had my Ig pool completed 4 weeks ago. We started using it 7/29. I have never had any readable free chlorine in the pool by dipstick or color change test with the unit set at 50% on low speed or high speed, running it at least 12 hours/day, 7am to 7pm. I am using the TF-100 kit. My pool is approximately 36,000 to 37,000 gallons and my pb has the Intellichlor IC-40 installed. Chlorine pucks have been added once by my pb, and twice by by his pool maintenance company in response to low readings since the pool was opened. The initial water delivery contained 2-3 ppm FC. i never considered there might be a problem with the chlorinator even though FC was always zero because I had clear water and saw no algae and also because I am new to all of this.

    Last week we started growing a brownish green algae in patches of the deep end walls of our pool. Not staining- it's algae. The water, however, remains clear. Algae only on walls of deep end. I asked the pool maintenance guy and my pb about this and they said go up on the intellichlor to 70%. I was a bit skeptical that 50% output setting should produce a level of zero chlorine (the water on color change chlorine testing is always clear as water and the pool maintenance guy also got 0.3 ppm chlorine the day after shocking the pool by his own testing). I jacked it up to 100% and ran it for 12 hours on low speed (I have a 2-speed 2 hp sta-rite pump)-still zero chlorine. I then ran it at high pump speed for 12 hours longer-still zero chlorine. Then 24 hours straight on high pump speed- still zero chlorine. CYA is 50. pH is spot on at 7.2 to 7.6 (adding acid twice a week). Total alkalinity is 70.

    I shocked the pool last week and the algae cleared. It reappeared 5 days later (noticed it again 3 days ago), again only on walls of pool in deep end. Despite this, the water clarity is good. No green to it at all.

    The Intellichlor unit has all green indicator lights consistent with normal operation. It is working whether it is on high or low pump speed. I raised the issue with the pool maintenance guy. He tested the IC-40 cell and he says it is producing chlorine.

    What could be the problem here? Is my Intellichlor unit undersized for my pool (should I have the IC-60 instead)? My pb and pool maintenance guy (who "follows" the pool builder to get new clients, providing free pool school) say that I need to run it longer even after they left it on low speed for an additional 8 hours and high speed for another 7 hours. You guessed it- still zero chlorine. I told them that something needs to be done. It seems a foregone conclusion that the present unit is either not working properly (although testing reportedly shows a cell that does produce chlorine) or the pool is too large for the unit and overwhelming it. This unit has a "superchlorinating" function which is supposed to hike the chlorine level above 10 ppm from what I understand. I can't even get 0.5 on 100% output which is essentially the superchlorinating setting. Use of the pool has been modest as we don't have the patio installed yet.

    Please help. This is beyond frustrating and I would like to get this settled before the pool is closed for the summer. Thank you.
    36K Gal, 22x44 ft, Pebblesheen, Sta-rite 2 HP two-speed pump, Sta-rite 450 Cartridge filter, Sta-rite Maxitherm Propane Heater, Intellichlor IC60, Polaris 280 with booster pump, deep heat returns, Intellitouch Automation system with Mobiletouch wireless controller

  2. Back To Top    #2

    Re: Zero chlorine in pool with Intellichlor IC-40, algae gro

    search the forum, there are a number of posts on where to get a water sample to determine if the chlorinator is working.

    Also you should read pool school here to learn about the chemicals. Have you added any cyanuric acid (AKA conditioner)? Chlorine is very rapidly destroyed by the sun, CYA stabilizes it. In salt water pools we recommend that you have a CYA level of about 70-80.

    You can look at to see how much you need to add based on the size of your pool.

    You should get a good test kit so you can test the CYA levels and chlorine levels yourself. Pool stores are pretty much completely incompetent.

    You either want a TF 100 or a Taylor K2006
    17,800 gallon, IG pool, 595 sq feet (17x35x4.5 avg rectangle), Hayward 525 cartridge filter, diamondbrite, 2 hp 2 speed hayward tristar filter, Stenner 45mhp10 automatically chlorinating

  3. Back To Top    #3

    Join Date
    Jun 2012
    Louisville, KY

    Re: Zero chlorine in pool with Intellichlor IC-40, algae gro

    Something is not right at all. Either you're not producing enough CL for a clean pool or you're not producing enough CL to keep up with consumption of the algae.

    Go to pool school at upper right and read up on shocking process. You've got a test kit, you've got bleach, but this is on the PB in my humble opinion. You have no sanitizer. They need to fix, and they need to fix now without cost to you.

    I'm trying to help, but I don't know much about SWG. What is the test results for salt in the pool? I can't believe the PB would be so incompetent to not know a SWG needs mucho salt for your size pool. Hopefully others can chime in on sizing.

    I'm thinking through this and I keep coming back to you don't have enough salt, but I can't believe this would be so overlooked. Again, I don't know much about SWG but without proper salt levels, it will never produce enough CL. The amount of salt to add to the water for a 37k pool would be a pallet load with fresh water.

    Again, I don't know much about SWG...just trying to help. 37k gallons to reach 3000 ppm salt means almost 1000 pounds of salt to the water.

    Oh, welcome to the forum. These folks will get you straightened out right quick. I can hear the desperation in your post, that money you spent and having troubles with your brand new pool, no worries, we're here to help. A pool is supposed to be trouble free, and following this forum/guides mine truly is.
    18x36 inground vinyl lined, Hayward sand filter and tablet chrolinator, approx 18k gallon

  4. Back To Top    #4
    UN1017's Avatar
    Join Date
    May 2012
    Sacramento, CA

    Re: Zero chlorine in pool with Intellichlor IC-40, algae gro

    Welcome to TFP!

    Just as spidey07 says you need to follow (to the "t") the shock process in Pool School. That will do two things:

    1. Get rid of your algae problem
    2. Get your FC level up so your SWG can maintain once at the desired level.

    Pentair says your SWG is properly sized for you pool, but since you are near the upper limit of the unit, it is not a surprise that it could be having difficulty maintaining. If your salt level was off, your SWG should have told you by now.

    We got bits and pieces of your test results but give us a complete list like this:


    You have a proper test kit and clearly the ability/desire to take control of your pool, so I would stop looking to the pool service guy and only bother with the PB if your SWG is broken or there is something that they are clearly responsible for. When you have a minute update your location in your profile and put your pool specs in your signature line. The more info the better.
    15'x30' IG - Roman-style - 14K - Pebble Fina Classico
    Filter: Jandy CL460 Pump: Jandy Stealth SHPF1.5 SWG: Jandy AquaPure 1400 Cleaner: Jandy RayVac Test Kit: TF-100 w/SpeedStir

    Chlorine/CYA Chart----Extended Test Kit Directions----SLAM

  5. Back To Top    #5

    Re: Zero chlorine in pool with Intellichlor IC-40, algae gro

    Just a quick response to your questions- I will put info in signature line later today.

    Plenty of salt was added by pool service guy(20 forty pound bags) and I added three more to bring salt level to 3200-3450 (proper range). It has stayed in this range (per readout from intellichlor and my own testing). Again, intellichlor indicator lights say all is well with the cell's production, salt level, etc. ( all are green, not flashing). I have the TF-100 test kit.
    On another forum, Scott, whom you all probably know as Poolguy, commented that the unit is undersized because the rating of the IC40 is based on 100% output for 24 hours. What I take it to mean, based on what Scott indicated, is that a 40,000 gal pool would need to have the IC40 run at 100% output, with pump on 24/7 (which very few people do) to maintain adequate FC. Maybe I did not interpret this the right way but I think I did.

    Although stabilizer level might be slightly on the low side, I can't believe this thing can't produce any measurable chlorine based on that alone.

    I appreciate all of your responses and any additional ones. Thanks
    36K Gal, 22x44 ft, Pebblesheen, Sta-rite 2 HP two-speed pump, Sta-rite 450 Cartridge filter, Sta-rite Maxitherm Propane Heater, Intellichlor IC60, Polaris 280 with booster pump, deep heat returns, Intellitouch Automation system with Mobiletouch wireless controller

  6. Back To Top    #6

    Re: Zero chlorine in pool with Intellichlor IC-40, algae gro

    A couple more things....

    Your interpretation of Poolguy's comment is correct. SWG ratings are typically at 100% output for 24 hours/day.

    One possibility is that you have the beginnigs of algae and all of the chlorine being produced is quickly working to kill the algae.

    A SWG isn't really capable of raising FC to target FC from zero. It is usually recommended to get the FC to where you want it by adding bleach. This will be especially true with the relative size of your unit.

    To really understand what is happening, an accurate CYA number is needed.

    If it were me, I would raise FC with bleach to around shock level for your CYA level and do an OCLT to see if there is algae. If you pass the OCLT (no algae), then trend the FC over several days without adding bleach to see how well the SWG keeps up.

    Good luck!
    23,000 IG Plaster pool w/ spa, Pentair FNS Plus 48 DE Filter, Hayward RS1000 Main pump, Polaris booster pump, CPSC48 SWG, Legend pool sweep. Dallas, Texas, Full sun, Taylor K-2006

  7. Back To Top    #7

    Join Date
    Jun 2011
    Long Beach, CA

    Re: Zero chlorine in pool with Intellichlor IC-40, algae gro

    Your main problem right now is that you have algae in the pool and are trying to control it with the SWG. A SWG is meant to keep your chlorine at a stable level only. It will not clear a pool with algae given your pool size and SWG size. The good news is that you have the tool, TF-100, to clear up this problem but you need to follow the advice here at TFP to avoid putting anything in the pool that you do not need.

    You need to follow the shock process, pool-school/shocking_your_pool. This is a process and must be completed or else the algae will never go away. Three criteria must be passed before the shock process is finished:
    1. The water is clear.
    2. CC<=.5
    3. Pass the OCLT, pool-school/overnight_fc_test

    Please post all of your test results:

    We can help you some more once we see these results.

    I did read Scott's reply in the other forum and he is correct in saying that your unit is undersized for your pool. To compensate you will have to run the pump longer than needed and run the SWG at a higher percentage than normal. This will cost you more in electrical costs and the cell will have a shorter life span. When sizing a SWG the unit should be rated 2 to 3 times larger than your pool size.
    16k gal plaster with raised spa, Jandy DEV60 filter, 2 HP 2-speed SHPF Jandy Stealth pump
    Hayward Aqua Rite T-15 SWCG, Jandy LXi 400k BTU NG heater, 350 sq.ft. of Sun Star solar panels, TF-100 Test Kit, Dolphin s300i Cleaner
    Test Kits . Pool Math . Chlorine/CYA Chart . The SLAM Process

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts