Pentair IC40 chlorine production down

[tpribors]

Our pool is 21000 gallons. At the beginning of the season (and for prior years) I ran the IC40 at 60-70% for about 8 hours per day to get good chlorine levels. Lately the chlorine in the pool has been lower than what the cell used to generate so now I'm having to run at 90% just to get hardly anything. The "More" self test says 40%. It's been a warm summer here in Vegas and water temp is mid 80s (83-85) in the morning going up to 89 (with solar heater) by mid afternoon. CYA was down to 50 and I've kept it at 70 so I added some more but that doesn't seem to help.

Sometimes after a big storm or something I would put the unit on SuperChlorinate mode and overnight the test strip would be off the chart. I just did it the other day and overnight running did raise it up but not as much as in the past.

The unit is 5+ years old (we are now in season 6). I've cleaned it and there is little calcium buildup and the plates seem to be in good condition.

So the question is do these units produce at a steady rate forever or as they age should I have to bump up the output to keep up?

 

[mknauss]

The SWCG output will degrade slightly but really should not be noticeable. How are you doing your testing? If my CYA drops below 70 the FC consumption goes way up.

 

[ajw22]

What is your salt level? Tested by what?

 

[tpribors]

Thanks for the responses!

Re #2: I test almost daily with AquaCheck test strips. This particular batch doesn't test CYA but I take a sample in to Leslies whenever I need acid. The last of the strip tests with CYA was 4-6 weeks ago and it was in the 50 range.

The Leslie's store I usually go to used to use the chemical test but now they use some kind of cartridge based test (this test uses a relatively small amount of water injected using a syringe into a disc for all of the chlorine/ph/alkilinity/calcium/CYA/metals/phosphate/salt tests). Both tests correlated well to the strips. I do their test because they have salt and phosphate tests. I had reason to doubt the Phosphate results (it went from 200 to 2500 in two weeks) so I took a sample to another store with the chemical tests and the cartridge and chemical tests did correlate.

So to #3: Salt results were 3000 using the meter test and 3200 using the cartridge test. My Pentair system however, has always reported the salt level higher than this. Today it is 3900. In fact, I had the IC40 replaced after the initial installation because the reading disagreed so much. The replacement read the same. I tried to get them to replace the main board but they wouldn't. The Pentair docs say it will auto-shut down at a little over 4000 so I try to keep it at the 3700 that the docs say they want as measured by the Pentair system. (Salt reading does increase with water temp, and like I said earlier, water temp during salt cell operation will range from 83-90.)

 

[tpribors]

Just another tidbit although I think it's probably "normal" - I have to add about 1/2 gallon of acid (31%) every other day or so to keep the pH down and the chlorine up. Sometimes I need a little more. I like to keep the pH at the lower end of the 7.2-7.8 range. I know the chemical reactions that the salt system uses to generate chlorine. It does consume more during hot weather. Keeping pH is mostly the reason I run a daily test strip.

PS. I see "mknauss" is in Laughlin, NV so you know about the pool in the desert...

 

[tpribors]

Is there a way to "test" the Pentair SWCG? Leslies at one time had a testing unit that could test Hayward and similar units but it didn't handle the Pentair.

Can it be rebuilt? I suppose this has been covered somewhere but the quick scan didn't mention it.

 

[ajw22]

You need to get the K-1766 Taylor Salt Test to sort out what your real salinity is. A low actual salt level will give lower output.

 

[tpribors]

You need to get the K-1766 Taylor Salt Test to sort out what your real salinity is. A low actual salt level will give lower output.

I'm not going to invest in a boatload of test materials. I trust my pool place to do that. The Pentair unit has read high since the beginning and I just compensate for it. The people from the place that Pentair subs their warranty work through ran it through two different meter type testers and got the same results that were about 600 below what the in-circuit reading was. (Pentair docs say it can be +-500) Plus, the Leslies I went to used to have the meter type tester and went to the disc based system and the other store with the meter tester are all within 100 of each other. I'm confident the salt is 3000-ish.

 

[mknauss]

Without proper testing we cannot provide guidance.
Good luck.

 

[tpribors]

So you don't believe that the tests from two different locations using different testing methods aren't accurate? Come on. I'm an engineer and been measuring things for 50+ years this way and these results are verified. The salt is 3000+-. And has been for two years since the last water change.

What you're telling me is that I can't test a reputable pool supply company that does tests for thousands of people every week. I did the liquid tests for two years at the beginning. Cost me a lot of money and used the same exact materials that Leslies did and Leslies doesn't charge me

 

[ajw22]

Optimal salt level for the ICXX is 3600. If your salt is 3000 then you are 20% under and will get 20% less chlorine output.

Yup, there are many threads here of pool companies giving their customers inaccurate test results. It sells more chemicals for them. They have no business reason to be accurate.

 

[Stoopalini]

Optimal salt level for the ICXX is 3600. If your salt is 3000 then you are 20% under and will get 20% less chlorine output.

Are you sure about that? Everything I've read (no personal experience yet, mind you ...) has led me to believe the salt content doesn't correlate directly to the chlorine generation; or at least not to the extent you are stating (ie: 20% below optimal level will result in 20% less chlorine being generated).

 

[ajw22]

Are you sure about that?

In my experience chlorine output is pretty much proportional to salt level.

You see it being used in products like the low salt Hayward Aquarite sold outside the US. Uses a T-15 cell with half the salt for half the chlorine output. Give it the usual salt level and you get normal Aquarite output.

 

[Stoopalini]

In my experience chlorine output is pretty much proportional to salt level.

You see it being used in products like the low salt Hayward Aquarite sold outside the US. Uses a T-15 cell with half the salt for half the chlorine output. Give it the usual salt level and you get normal Aquarite output.

Interesting ... Pentair lists the same salt content requirement for all their cells (IC15 all the way to IC60). They state 3600ppm as optimal, with 2600ppm the low cutoff, and 4500ppm the high limit. They don't have different ppm requirements based on the IC size.

 

[ajw22]

Interesting ... Pentair lists the same salt content requirement for all their cells (IC15 all the way to IC60). They state 3600ppm as optimal, with 2600ppm the low cutoff, and 4500ppm the high limit. They don't have different ppm requirements based on the IC size.

That is because they change the plate size in the cells to produce smaller cells at lower cost. The cell plates are the most expensive component in the cell.

A cell is designed for a plate size and salt ppm combination. Some cheap cells require 4000 ppm or more salt to get rated output because they save money with small plates. Those cheap cells also tend to burn out quickly.

 

[Jimrahbe]

I have the IC40 in three pools.. I don't see any correlation between the salt level and the amount of chlorine produced.

Obviously, you need to stay in the approved salt range.

I must admit that I have never run the cells at the upper end of the salt range..

Thanks,

Jim R.

 

[tpribors]

Today I pulled the cell to look more closely at it. The last time I cleaned it I just ran a quick acid bath and put it back because it wasn't too dirty, but I didn't inspect closely. Today was an extra maintenance day so I pulled it to inspect closer.

I conclude based on the wear at the trailing edges in the picture below that about 1/2 the plates have lost material. The picture shows two sets marked that have lost some material at the end of the plate and have lost their shiny silver end. Note the last one is not bent, that's just the optical illusion of the picture angle. It is actually worn in a curve less at top and bottom, more in the middle. It looks like there is wear on outer left two, three middle and right two. If these are "out of the circuit" that would explain why I'm down to about 1/3-1/2 production...

Oh well, mfg date is in 2015. Even though it says 40% I guess 5 years out of one of these isn't too bad.

 

[tpribors]

How are the different IC20/40/60 different? Is it possible the blades that look fine aren't used in the IC40 and it's not that they are still working but simply that they aren't used and that the blackened ones are the operational panels?

 

[mknauss]

How often did you clean the cell with acid? Each time you reduce its life. Proper water chemistry maintenance can eliminate the need to clean with acid.

The different cells use different lengths of cell plates. Also number of plates, I believe.

 

[tpribors]

How often did you clean the cell with acid? Each time you reduce its life. Proper water chemistry maintenance can eliminate the need to clean with acid.

The different cells use different lengths of cell plates. Also number of plates, I believe.

I generally clean the salt cell whenever I clean the filters. Once in the spring when we bring the pool on line, then every 3 months until I put it down for the winter usually in mid-Nov (yes, with the solar heater and blanket I usually get from mid-March to April to mid November). If we get a big dust storm that makes the bottom look like a corn field I will clean the filters and the cell (we haven't had a dust storm like that yet this year). The cell has never built up enough calcium to worry too much about. There is never more than a crust on the leading and trailing edges of the blades. I usually leave the wash on for about 5 minutes then rinse with water and the crusts almost always fall off. I think maybe I've only had to repeat it a couple of times in the 5 years.

As you are probably aware being in Laughlin (we are in Las Vegas) out of the tap the CH level is abysmal. We've never needed a water softener for the house until we moved here. I drained and filled it in early 2019 and the CH level is now at 600 (627 from the disc based test, 627 from the same water sample using the chemical test).

In reading here I think the phosphate level may be a contributor to the chlorinator problem as well. Its at 2500. I had stopped chasing it since the removers didn't seem to reduce it as much as they projected it should but last weekend I noticed some algae building up in two corners that don't get as much circulation as other areas and this is with the chlorine at 3. (and that is what started this whole discussion since to get there I had to run the cell at 90% duty cycle as mentioned above.) I just dosed it with some BIO-DEX Max but haven't gotten a test yet. I need acid so I'll check it later this week.

All in all if it is the cell I got 5 seasons out of it so I don't think that's too bad...