IntelliChlor IC40 Issues

I have a 29,000 gallon in ground plaster pool with all Pentair products, IntelliTouch control, IntelliChlor IC40, IntellipH, IntelliFlo VF pump, IntelliBrite LED light, and FNS plus 60 filter. The system is a little more than a year old on most parts and some parts less than a year. The IC40 is a year old this month.

The issue that I am having is the chlorine level has been dropping steadily over the past month or so. The system runs about nine hours a day. It should be enough, it was in the past and nothing has really changed. Last year the highest setting on the SWCG was was about 75%.

I have increased the output level to 100% for the past two weeks but it is still dropping and the free chlorine level is only 1 ppm today. I checked the salt level and it is 3600 the CYA and it is around 70 ppm everything is within specs. The water temp is 92F. I took the IC40 of to inspect the blades and they are clean no build up.

The only thing that was out of the norm was every once in a while the light showing the salt level was would flash high, but the next day it would be fine. So, I don’t know if that means anything. Everything else normal. The bathing load is minimal just me and my wife, except on Saturdays we usually have friends over but only 4 or five actually ever get in the pool. Any ideas that may help me figure this out.

What are your test results? It's possible the swcg is working fine but the chlorine is being consumed by something.

Just had Leslie’s check the water. This is what they came up with

Free Available Chlorine .5 ppm Low
Total Available Chlorine .5 ppm Low
Salt 3300 ppm Ok
Cyanuric Acid 80 ppm Ok
Total Alkalinity 90 ppm Ok
pH 7.8 Ok
Acid Demand 5
Phosphates 500 ppb High

I can’t use PHOSFree to lower the phosphates, because I am using Fiber Clear not DE. I asked the Leslie’s staff if this could be the issue he said not at this level. He feels that the generator maybe going out.
Pentair tech support emailed me back and they think it is the phosphates.

On a more personal note, I like your choice in beer.

Thanks
Damon

I think most folks on this forum tend to discount phosphate testing as useless; except for the purposes of selling stuff like phos-free. I'm no expert, so hopefully someone who knows more can weigh in. Personally, I'd shock with bleach just to see if you have something that you're fighting (even if you don't, you need to get chlorine in the pool while you're working through this problem). If you shock and you were fighting something, you'll probably have a nonzero CC level right after shocking. Also, if you are fighting something and you clear it out by shocking the swcg may then be able to keep up.

You should call pentair on the phone and ask them to help you troubleshoot. When I bought my house the swcg control board was bad and there was a diagnostic mode on it that tech support (in my case goldline/aquarite) used to accurately ID the problem based on the diagnostic numbers I read off to them from the control panel. Is the system still under warranty?

I also think if it were my pool, I'd try shocking the pool. Your cl is really low and you could have something starting to brew in the water which could be consuming the chlorine. See if you lose more than 1ppm of chlorine overnight after shocking.

Thanks for the info, I shocked the pool today with the powder shock, but I see it is mentioned using bleach for shock. Is liquid bleach better then the powdered stuff, should I shock it a couple times in a row? I also noticed a small spot (6 inch) of what appeared to be a greenish algae in the shade by the waterfall. I used the pool brush and it came right off. Other then that the pool is crystal clean or it at least it appears that way.

Thanks
Damon

Depends on what the ingredient is in the powdered shock. (I just noticed that you have a plaster pool and didn't list a calcium hardness reading in your post above.) If the shock powder is dichlor, then no, I wouldn't use it. It has stabilizer in it and your CYA level is already high enough. If it is cal-hypo, you might be able to use it but can't comment on that unless we know your CH reading.

You should shock until you can go from sundown one evening until within 2 hours of sunrise the next day without losing more than 1ppm of cl, and have no greater than 0.5CC. While you are shocking, test a couple times per day and each time take the cl back up to 25pm. (See the Best Guess Chlorine Chart in my signature below for the connection between CYA and chlorine levels.)