Chlorine Levels Drastically Low w/ green lights on SWG

[kc101]

I had my 24,500 gal, gunite pool built w/ a Pentair Intellichlor IC40 installed in 2007. For nearly 5 years the SWG worked beautifully w/ no complaints. During that time, I've maintained the SWG's sanitizing output levels at 40% w/ no problems. In March of this year I replaced it w/ another in kind.
For the last month I have been struggling to maintain a free chlorine level of 2.0 in my pool. I've maintained my PH (+,-)7.5, CA (+,-)60, TA(+,-) 100, Salt(+,-)3400. I've increased my run time from 8 hrs/day to 12 hrs/day. I've also increased the SWG's sanitizing output level to 60% and recently up to 80%, resulting in little or no change to my free chlorine level.
I have just completed a "Boost" mode, running my sanitizer at 100% for the last 24 hours. My chlorine level is: FC= 1.4 & CC= 1.0.
Is it possible that my SWG is defected? I'm really at a lost as to where to turn from here.

[Watermom]

I cannot help you with your SWCG question, but someone should be along who can. I just wanted to tell you that you should get some bleach and put in the pool while you work out this problem. With that low of a FC reading and a CC reading of 1.0, you may have an impending algae bloom. Go ahead and shock the pool to the needed level based on your CYA reading. (Check the Best Guess Chlorine Chart in my signature below.) For reference, in your pool, each gallon (4 quarts) of 6% bleach will add about 2.5ppm of chlorine.

[JimK]

I had my 24,500 gal, gunite pool built w/ a Pentair Intellichlor IC40 installed in 2007. For nearly 5 years the SWG worked beautifully w/ no complaints. During that time, I've maintained the SWG's sanitizing output levels at 40% w/ no problems. In March of this year I replaced it w/ another in kind.
For the last month I have been struggling to maintain a free chlorine level of 2.0 in my pool. I've maintained my PH (+,-)7.5, CA (+,-)60, TA(+,-) 100, Salt(+,-)3400. I've increased my run time from 8 hrs/day to 12 hrs/day. I've also increased the SWG's sanitizing output level to 60% and recently up to 80%, resulting in little or no change to my free chlorine level.
I have just completed a "Boost" mode, running my sanitizer at 100% for the last 24 hours. My chlorine level is: FC= 1.4 & CC= 1.0.
Is it possible that my SWG is defected? I'm really at a lost as to where to turn from here.

It's entirely possible that your new cell is defective and has failed prematurely. Do you have somewhere you can take it to be tested? I would think it's still under warranty.

[kc101]

Looks like my next step is to call Pentair & ask about testing/trouble shooting. Thx

[JimK]

Looks like my next step is to call Pentair & ask about testing/trouble shooting. Thx

Meanwhile, like Watermom said, get some bleach in that pool ASAP!

[kc101]

I spoke to a Pentair technical representative concerning my IC40 and he thinks high phosphate levels could be causing the problem. I see nowhere on my K-2006 how to test for phosphates. My current levels are: PH 7.3, CA 50, TA 100, Salt 3400. When not adding bleach, my FC is struggling to maintain 1.5. I've increased my run time to 16 hours & my SWG output levels to 100%.

Can someone tell me how to test for phosphates? Thx

[kelemvor]

Phosphates aren't something we'd normally test for because maintaining adequate chlorine levels makes them entirely irrelevant. My local pool stores will test salt cells for me (no charge because they hope to sell replacements), which I'm pretty sure simply involves sticking the cell in a bucket of salt water, and connecting it to a controller and verifying it produces the bubbles and verifying chlorine was added to the water.

Did you get that salt reading from your SWCG control board or from a separate test kit? If the former, you should get a test kit for salt - either a k-1766 or aqua check salt strips. You can probably find the aquacheck strips in a local pool store, perhaps even the 1766 (I got mine in a local pool store). You can also order them from the links to amazon.com provided here: http://www.poolforum.com/pf2/showthread.php?14994

I didn't see a CYA reading in the information you posted. If you have low (or no) CYA it could cause the symptoms you describe as the generated chlorine would be quickly wiped out by the sun. Once the chlorine level is below the level you need based on your CYA then you could have stuff growing in the pool which would further increase the chlorine demand and correspondingly your FC reading. You definitely have something growing with a CC reading of 1.

So, I would:
1. Test the cell
2. Verify your salt reading
3. Clean up with regular chlorine/bleach as watermom suggested.

If the cell and salt readings are OK then it may be a matter of simply getting caught back up. SWCG are great for producing chlorine slowly and preventing algae, but once growth has started it's VERY difficult to clean up without adding sanitizer manually.

[kc101]

I've got no SWCG control board just the IC40 & it's LEDs. For salt testing I've got a LaMotte Salt Tester that I've had for a few years. My levels have been fine.
CYA reading has been 50-60 ppm, so that's not the problem. (I abbreviated it CA in original post).
I'm testing FC,TC,PH, CYA CH & TA w/a Taylor K-2006. All have been fine. That's why I suspected a problem w/ the SWGcell.
I've been adding bleach and getting my FC up to 10 ppm. I thoroughly brush my gunite, removing any algae that my exist. Then when I let just the SWG pick up from there the FC steadily decreases to 1.5 ppm, regardless of my run time (now up to 16 hrs) our my SWG output setting (now up to %100).
The Pentair technician claims it has to be high phosphate levels. I'm not convinced. I just ordered a Taylor K-1106 and will get back to him when I confirm my phosphate levels.
Thanks for your input kelemvor