Pentair IC40 and low chlorine level, nitrates?

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bobca1

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Feb 27, 2016
40
Agoura Hills CA
I'm having problems this season with the system being able to keep chlorine in range. System is about 3 years old. First year worked great consistently had 2-3ppm all summer with IC40 set at 25%. Second year started out ok but then I had to increase output to 50% to keep chlorine in range then started getting lot of white scale collecting below the returns so I acid cleaned the cell and after cleaning it was good at 25% again. So I clean the cell now when I start to see low chlorine which was couple more times in past year, but now this is not helping. I cleaned the cell few weeks ago and keep increasing the output but I can't get chlorine level up. I know it's making sanitizer because if I do a 24 hr super chlorinate cycle I will detect chlorine but barely 1ppm. Had the water tested at local pool store to confirm my numbers. PH, CYA, are good. I was told I have nitrates at 30ppm and will need to drain my pool and refill. Does this sound right are the nitrates consuming all the sanitizer, or could the IC40 be failing?

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The problem could be simpler but it is hard to know without proper test results from one of the recommended test kits we talk about here- either the TF100 or K2006.

If you have the right amount of chlorine for your CYA level in your pool then you don't need to worry about nitrates. It could be that you have an underlying algae issue which you have been managing to keep at bay by the regular addition of chlorine from your SWG. We also don't trust pool store results as they are often unreliable.
 
By far, the most likely reason for good success one year, and then spotty results creeping in, is algae gaining ground due to chlorine levels that are too low for your CYA level. Clear water is not a sign that algae is not growing in the pool. Only your own test results will tell you for sure. I don't sell test kits or anything, but if I did I would sell the TF100. I believe if you include the speedstir, which people here really like, you'll get free shipping. TFTestkits.net. You will save that money back before the summer is over through pool chemical savings.

I'm with Jezza on nitrates - eliminate algae and they don't matter.

Have a quick read through this article: TFPC for Beginners

I don't think there's anything wrong with your saltwater chlorinator, because if there was, you would not have chlorine at all. Many people who use TFPC never need to clean their saltwater chlorinator cell, because the most common cause of the flakes is poor water balance, and is easily avoided. (provided the pool store is avoided!)

So, a couple things to do. Click the link in my signature - Read before you Post - and do the part that says "Edit My Signature" to add your pool details. You'll also see how to post your water test results. You can post the pool store results, but please note the source when you post, so that anyone answering is aware of the source. These steps will help you get the best possible advice.

Beyond that, let us know which way you'd like to go, and if you'd like to try TFPC, start taking a look at pool school. (button at the top of this page)
 
Yes I am getting some light green algae in the deep end of the pool that easily brushes off, which I know from experience is due to lack of chlorine. I test it and its 0 so not much surprise there! I have Taylor k2006 kit using the sbd titration test so i know my test is accurate. My CYA is at 60, which I think is on low side, the pool guy that did my setup wanted it at least 80. I know I need to get the chlorine up which I can do quickly by adding liquid, but my question is why is the chlorinator not able to keep up? CYA too low, or the algae or nitrates sucking up sanitizer fast as its being made? The chlorinator is at 50% this past week and chlorine is still 0. I am running another super clorinate cycle but when I tried that last week it only made it to 1ppm after 24 hours. Thank you both for quick reply! Thats why I posted here I knew I would immediately get expert advice, have had great success posing here previously! I'll check your links out tomorrow.
My pool is in ground plaster about 20k gal. Attaching full test results (from Leslie's)
 
bobca1 said:
Yes I am getting some light green algae in the deep end of the pool that easily brushes off, which I know from experience is due to lack of chlorine. I test it and its 0 so not much surprise there! I have Taylor k2006 kit using the sbd titration test so i know my test is accurate. My CYA is at 60, which I think is on low side, the pool guy that did my setup wanted it at least 80. I know I need to get the chlorine up which I can do quickly by adding liquid, but my question is why is the chlorinator not able to keep up? CYA too low, or the algae or nitrates sucking up sanitizer fast as its being made? The chlorinator is at 50% this past week and chlorine is still 0. I am running another super clorinate cycle but when I tried that last week it only made it to 1ppm after 24 hours. Thank you both for quick reply! Thats why I posted here I knew I would immediately get expert advice, have had great success posing here previously! I'll check your links out tomorrow.
My pool is in ground plaster about 20k gal. Attaching full test results (from Leslie's)
Click to expand...
95131c993184778545dff636d9d7a41e.jpg
 
Thanks, that's helpful

With 60 CYA, your bare minimum FC would be 3 PPM to prevent problems and the target would be 5 PPM FC, so that's what let the algae get started. You've seen algae, so that gives you two pieces of evidence that you need to SLAM. The quickest fix is start that right away, but you need a FAS-DPD test to do it because you will use FC levels around 24 PPM FC. You will also need the CC (combined chlorine) test to know what's going on, and to know when the SLAM is finished. You can buy just the FAS-DPD kit from TF test kits.
Pool School - SLAM - Shock Level And Maintain

To verify the need for a SLAM, it's possible to do an OCLT, but I'm quite sure the pool will fail the test. You would raise the chlorine with chlorinating liquid up to about 9 PPM FC and then do the OCLT Pool School - Perform the Overnight FC Loss Test (OCLT)
It tells you if organic contaminants are causing the FC to fall. You do this with the SWG off. You top up the chlorine just before sunset, wait 30-45 minutes for it to mix. Test the FC, then leave it till morning. In the morning, before sunrise, ensure its mixed (either run pump for 30 minutes or leave it on overnight). Measure FC again. If it drops more than 1 PPM between the two readings, the only explanation is organic contamination. If the test fails, then it's the same process - SLAM to eliminate the source of the problem.

Once the algae problem is eliminated, your SWG is capable of maintaining a safe FC level. To replace 2.5 PPM FC with an IC40 in your pool when it's clean would take about 7 hours at 100%.

I think 3000 PPM salt is just enough for your IC40 and wouldn't hurt to be a tad higher, but that would be in your manual. The TA is a bit high but that can be dealt with later, to reduce your acid consumption a bit. But but but, I'm basing that on pool store numbers, and I'd rather not trust those at all. I would trust your tests with a kit over theirs any day.

Read up on the SLAM and how you can fit it in to your life, get the test kit ordered, and we can take it from there.
 
We really shouldn't trust the pool store CYA test either. They tend to under-report CYA, which would lead to a SLAM that either takes way longer or doesn't work. So consider either the full TF 100, or order the CYA test along with the FAS-DPD kit. Consider the XL option (extra FC reagents) because the SLAM uses a fair bit.

It's going to see a bit daunting, but then your maintenance will drop down to minimal, and the water will really look and feel great as well.
 
Yep unfortunately your experience is familiar to me- and it was what led me here a few years ago and started my journey with TFP. If you have had visible algae you are going to need to SLAM the pool.

Once you get algae, it consumes large amounts of chlorine and a SLAM is the only way to get rid of it once and for all. It is about adding elevated but targeted levels of liquid chlorine for a sustained period. Note that this a process and not a one time shock. Things like phosphates and nitrates are just something made as a big deal by pool stores to sell you chemicals.

At some stage you have dropped below the minimum FC for your CYA level and this is the opportunity algae needs to set in. Unfortunately warmer temperatures tend to make the problem worse. See this chart Chlorine/CYA chart

SWG's are great at adding small doses of chlorine slowly over a regular period of time. Therefore you need to regularly test and adjust either your chlorinator run time or pump run time to ensure that it is making chlorine to keep you around the target range for your CYA level at all times.

Could you give us a full set of results from your K2006? You may also need some extra supplies of the testing reagents particularly the FAS DPD testing reagents
R-0870 powder and R-0871 titration reagent for an anticipated SLAM and some more CYA R-0013 reagent is always handy.
 
You're right their test was way off. I just tested myself used up my last R0013 and I get CYA of 90. Also last night before posting I added 1 bag of their "powder plus" and the SWG has been running 100% for past 12 hrs. Just checked FC is now 5ppm and CC is 0. I'll read up on SLAM now. I am heading out of town for vacation in one week and will be gone for 10 days so if I do SLAM then i'll start it when i get back from the trip.

Some more information. I do use a cover to control evaporation and keep the pool warm. Usually the cover stays off for the weekend. Pool temp stays around 85-90. I notice when the cover is on I get more algae.
 
And they were wrong on salt too. I checked it using K-1766 kit and I get 3800. The SWG is registering 3950. So I am done with Leslie's they were the ones that told me to add 2 bags of salt in the spring. I guess another example of them just trying to sell more chemicals - I'm sure no surprise to folks here on TFP ;) So given these salt results and the high CYA looks like I should drain and replace a foot or so of water? I need to fix some tiles that came loose anyway that will make that easier to do at same time.
 

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Check out the link in my signature "Read before you post" and it will explain how to add your pool details to your signature. There's some other great tips there that will help you get the best advice. We can discuss the drain/refill when you're ready to get underway. Glad you're able to take charge of your pool with better information :)
 
Yes as much as it pains- a drain is in your future and I would definitely wait until you get back. I wouldn't stick anything else in your pool now other than bleach/liquid chlorine.

Is it right to suggest you guys have water restrictions? I would suggest a 50% drain if that is possible to mainly get your CYA down to a manageable level for your SLAM- if not you can SLAM but it will just require a higher level of liquid chlorine.


I guess you have shown that it is always best to do your own testing- no one cares about your pool more than you.
 
Jezza said:
Yes as much as it pains- a drain is in your future and I would definitely wait until you get back. I wouldn't stick anything else in your pool now other than bleach/liquid chlorine.

Is it right to suggest you guys have water restrictions? I would suggest a 50% drain if that is possible to mainly get your CYA down to a manageable level for your SLAM- if not you can SLAM but it will just require a higher level of liquid chlorine.


I guess you have shown that it is always best to do your own testing- no one cares about your pool more than you.
Click to expand...
Yes water restrictions still in place at least for outdoor water watering I believe pools too. I should only need to remove 10% to get the salt down to 3600 and CYA to 80. Or maybe I can just add liquid Clorine for next couple months to keep at 5ppm and deal with later this summer.
 
Just a heads-up and reference point, for CYA 90, your minimum FC level for keeping a clean pool clean is 5 PPM FC. The target would be 7 PPM FC. With an algae load in there, I would suggest higher until the SLAM can be done.
 
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