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.