Pentair IC 20 not keeping up with chlorine generation!!!

[bchimbor]

Year old above ground pool, gunite, screened in FL. Water chemestry good.. PH 7.6, Salt 3600, CYA 80, Phosphates almost 0, Alkalinity 100, Calcium 70, Nitrate 0. But chlorine at 0 even at 100% output for 8 hours a day with IC 20. This is the 3rd unit from Pentair in a year!!! First one died after 8 month, second was tested to produce at dimished capacity. It seems I have a huge chlorine loss. I have to add liquid chlorine ( gallon) every other day. It is a mystery so far to all people I spoke. BTW.. water temperature is 80F, air temperature 83 F. No pool use in about a week. After adding gallon liquid chlorine during day... get up to 4ppm, but next day mid day is at 0. The IC 20 is still running even I add chlorine. Can somebody help me please? What can cause such a huge chlorine loss? Is the 3rd unit I got also bad? Why can I not generate chlorine? BTW. the unit is only 3 weeks old and clean. PLEASE HELP!!

Barb

 

[Melt In The Sun]

Welcome to TFP!

How large is your pool? I presume it's in-ground, not above-ground as you stated.

How are you testing :?: Strips, drop-based tests, pool store? Since you have phosphate and nitrate results, I'm guessing they're pool store results. We always recommend that people get a good test kit (TF-100 or Taylor K-2006, see TF-testkits link in my sig), rather than using test strips (horribly unreliable) or a pool store (some know how to test, most don't).

Something funny is definitely going on with your chlorine levels. Here are a few possibilities from off the top of my head:
- your pool is much too large for an IC-20 and you need a bigger cell
- you have algae growing (may be there even if you can't see it) and it's consuming chlorine as fast as you are adding it
- your CYA number is wrong and you don't have enough, so the sun is burning off your chlorine very quickly

On an unrelated note, assuming those test results are correct, your CH is too low for a gunite/plaster pool.

 

[bchimbor]

Sorry, it is NOT above ground. It is in ground...It is 14,000 gal. Water testing is done on weekly basis with a professional company. There is no algea in the pool and have professional maintenance each week... filters are all clean and main filter in Pentair unit is brand new ( replaced after one year). Stabilizer is allways between 60 to 90 for the past year. The chlorine should be between 2 -4 pmm. I do not seem to be able to generate that ( but was able last year when it was originally installed... I had to even lower the output to 60% at 5 hours a day.

 

[openpool]

Hmmm....do the internal blades get bathed with muriatic acid every quarter?

It might not be a bad idea to find a way to corroborate the pool company's test results with a DIY test with either of the 2 kits that everyone loves to talk about here.

 

[dmanb2b]

Sorry, it is NOT above ground. It is in ground...It is 14,000 gal. Water testing is done on weekly basis with a professional company. There is no algea in the pool and have professional maintenance each week... filters are all clean and main filter in Pentair unit is brand new ( replaced after one year). Stabilizer is allways between 60 to 90 for the past year. The chlorine should be between 2 -4 pmm. I do not seem to be able to generate that ( but was able last year when it was originally installed... I had to even lower the output to 60% at 5 hours a day.

Welcome to TFP

Not doubting you but be very skeptical of testing by "professionals" and the related maintenance. They may be using strips which are well know to be inaccurate and if they really provided any value add maintenance, you wouldn't be here struggling with a chlorine demand issue on your own. There are great maint co's out there, but as many members here will tell you there is no way to know what's going on in your pool unless you can verify these "good" results for yourself.

Have you had a chance to read through pool school? If your CYA is between 60 and 90, your FC should be between 4-7ppm. It sure sounds like you have organics and may require a good shock cycle. The best way to confirm if this is the case is to perform and overnight FC loss test. pool-school/overnight_fc_test

You'll be well served by investing in a good drop based test kit, such as the Tf100 from tftestkits.net or the taylor k2006...gives you peace of mind and takes the mystery out of pool water chemistry

 

[bchimbor]

This is brand new unit only 3 weeks old and blades are shiny. I have tested my pool water with 3 indepent family owned pool companies. They all had the same results as stated above. There does not seem to be anything wrong with the water as far as they can tell. I assume they did much better job in testing ( even metalls) that I can ever do with a bought kit. Even when the Pentair rep was here 3 weeks ago he had a test unit and used my pool water to see the generation. It was perfect. He also had no answer for me and told me that all is according to manufacturer's recommendations. IT is a big mystery. I hope I do not have to drain the pool and replace water!!

 

[bk406]

I assume they did much better job in testing ( even metalls) that I can ever do with a bought kit. !

Actually this isnt true. You can do a much better job with a drop based kit.
3 units in that period of time tells me something else is wrong.
A few questions. When the IC-20 is running, is the green cell light on? Is the green salt light on?
Have you tried running the pump and the IC-20 24/7 to see if you can get the chlorine level up?

You should do an overnight chlorine loss test as described here

pool-school/overnight_fc_test

This should give you an idea if there is something in your pool using up chlorine. The other issue is that the IC-20 could be a bit small for the pool. I have an IC-40 on a 14,000 gallon pool and it works great. The IC-20 is designed to chlorinate a 20,000 gallon pool, but at 100% output.

 

[dmanb2b]

This is brand new unit only 3 weeks old and blades are shiny. I have tested my pool water with 3 indepent family owned pool companies. They all had the same results as stated above. There does not seem to be anything wrong with the water as far as they can tell. I assume they did much better job in testing ( even metalls) that I can ever do with a bought kit.

Metals perhaps they can test that are not in a TF100 or Taylor kit I recommended, but as for the other parameters you are assuming incorrectly. There is no mystery here. Try this...1) turn off your SWG, 2) add liquid chlorine after sundown to reach 5ppm FC. 3) Measure your FC and record it any time before bedtime. 4) Wake up before the sun hits the pool and re-measure FC. If you lost more than 1ppm, you have organics consuming your FC faster than the swg can maintain and you need to shock. Shock is a process, not a product, if you do not understand this feel free to ask and we can explain. It's that simple. Two main drivers deplete FC, sunlight and organics...elimate the sunlight and you can test to see if you have organics.

Since their testing is so good, have they confirmed your CC level is 0.5ppm or less. Here is what I can measure with my "at home kit"

FC up to 50ppm with 0.2ppm increments (+/-0.2ppm accuracy)
CC - Same as FC
TC = FC + CC = TC
PH 6.8-8.2 to within 0.2 accuracy
CH - 10ppm increments to well above 1000 if needed, but honestly you are better off draining if that's the case
TA - 10ppm increments
CYA - 0-100ppm to within +/- 10ppm accuracy
Accucheck Salt strips = +/- 200ppm accuracy

Honestly, that about as precise as you'll ever need to be with a residential pool, again unless metals are a concern and that is not causing an FC demand issue as you have described.

Not many independent pool shops spend that much on reagents, especially when they are in the business of selling chemicals you usually do not need.

edit...BK406 is giving you great advice as well

 

[bchimbor]

Thanks for all the tips. Very valuable. It seems the tip about organics maybe the key. I did actually test chlorine about two weeks ago in the evening ( was 3ppm after dumping a gallon chlorine that day) and then next morning ( was down to 0.5 ppm). I even tested the IC20 on boost button for 24 hours to see if it As far as the testing, none of the companies are using strips. Even the Pentair guy did test with drop kit very much like the one recommended. It did seem to me that the readings were accurate since all four different people and companies came out with the same results using drop kits. But none of them could explain my dilema. The Pentair guy was just harping on phosphates and that they have to be 0 in order for the unit to generate ANY chlorine. That seems odd to me. He even claimed that because I have screened in pool that this is what is causing my chlorine loss. Gee...do you know how many people have screen in pools in FL??? You can not be without it. How come other millions of people have no such problem? As far as the unit size IC20 ...it was recommended by pool contractor and Pentair. I think it was ok size because last year during the hot summer with the original unit I had to go down to 60% at 5 hours per day and was keeping consistent 3ppm chlorine. But that unit died. Was not sure if Pentair products are reliable. I do regret after so much hassle ( 3 units later withing 13 month!) to bought it. My neighbors have Hayward for 6 years and NEVER had problems.

I will read up on how to schock the pool. Any good advise how to do it properly is welcome. I hope this will solve it.

 

[dmanb2b]

The Pentair guy was just harping on phosphates and that they have to be 0 in order for the unit to generate ANY chlorine. That seems odd to me. He even claimed that because I have screened in pool that this is what is causing my chlorine loss. Gee...do you know how many people have screen in pools in FL??? You can not be without it.

Run from this guy as fast as you can. Phosphates are the new craze at pool stores to sell products. Phosphates are a food source for algae, but if your pool is properly chlorinated, you do not need to worry about phosphate levels.

Shocking your pool if you lose more than 1ppm FC overnight is your solution

Here are the instructions from pool school (button on upper right of this page)

pool-school/shocking_your_pool

 

[Guest]

I had a similar issue with my Goldline AquaRite. Had to run my pump 10-12 hours a day to keep up and always adding Liquid CL during the hot months. I gave up and went to a peristaltic pump (Rola-Chem) and a 15 gallon Carboy (Chlorine). Now I buy chlorine every couple months and the Rola Chem regulates my chlorine. I only have to run my pump 6 - 7 Hours during the summer months.

 

[susa]

this thread illustrates also one of the reasons I chose to install the Pentair IntelliChlor IC40 rated for 40,000 gallons but my pool is only 15,000 gallons.

hopefully OP gets issue resolved.

are there any useful pointers in the water balance for SWCG post?

 

[swbill]

I had a very similiar problem with my Aquacell T15 (see my post "Cannot maintain FC with SWG"). Turned out to be organics (nanscent algae bloom). Fixed by keeping correct shock level until the overnight FAS-DPD test indicated no FC loss. Make sure you get the right shock level (read the Pool School section on Chlorine/CYA Chart) and don't make the same mistake I did which was not shocking long enough. One last thing, you really need your own test kit, they are worth every penny. Good luck.