Auto pilot nano not keeping up with chlorine level


Apr 6, 2017
Bokeelia florida
We have a 6 month old pool that has a auto pilot nano salt system.
when the system was first started and was set a 50% it would keep the chlorine level at 7.5 free.
we reduced the level to 25% and it dropped to 4.0 free. During that time we added muratic acid to keep ph levels in check. The need for acid slowed till is leveled off at about 48 oz a week.
then we lost our chlorine level and had to add chlorine to keep a free level of at least 3.5.
i contacted the pool contractor and was told to check the phosphate and nitrate levels.
we had a phosphate level of 975 which we treated with phosfree and now have a 0 phosphate level.
we still are not producing enough chlorine to keep a level without adding liquid chlorine.
our water chemistry has been even this whole time with not changes.
pool contractor sent out a service company and they checked the system and said it is working. I did see chlorine gas come off the element when it was in a bucket. They said it is a problem with the water. So I took a sample to their store without telling them who the service company was and explained my problem and they said it is a bad system as my water tests just fine. Not sure what to do at this point. Below is the current water chemistry.
fc 0.5
tc 0.28
ph 7.4
hardness 250
alkalinity 100
cya 66
nitrate 10
phosphate 0
salt 3000
system set at 95% but currently on boost system runs 7 hours a day
have not had to add acid in 6 weeks since issue started
volts 15.5 amps 5.5 amp hours 3200
just added 128 oz of liquid chlorine to get a free level of 6.0

pool is 10,000 gallons
pebble tec finish
solar cover is on
phosphates were from city water supply none added since phosphate treatment

I am about to give up on the salt system because no one can give me an answer

thank you in advance for your help


Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
Bedford, TX

Welcome to TFP... A Great resource for all your saltwater pool questions... :splash:

I've sat here for a few minutes thinking about how to respond to your questions..

There are several tests that you can do that will verify if the SWCG is working or not, or if there is something in your pool that is eating the chlorine about as fast as your SWCG can produce it..

The problem is without an accurate test kit, you don't have the ability to run any of the tests.

One test that will tell you how much (if any) chlorine the cell is making is done by testing the FC level just after sundown and they again just before sunup. (With the SWCG on all night).. The difference in the FC levels will tell you how much chlorine the SWCG produced overnight when no chlorine should be consumed by your pool.

Another similar test, is to test your FC just after sundown and again just before sunup. This time with the SWCG off all night. If the FC level drops more than 1 ppm, then some organic matter in your pool is eating the chlorine

You can also capture the water out of a pool return with the SWCG running and then compare its FC level with the FC level taken in an area away form any return eyeball.

This site is dedicated to pool owners testing their own water and then only adding just what is necessary to keep their pool water crystal clear, safe, and sanitized.

if you are interested, you might want to read this...

Thanks for posting,

Jim R.


Apr 6, 2017
Bokeelia florida
Thank you Jim for your reply.
i did test the water at the joint just past the cell with the unit on boost and the free chlorine level was only .3 higher than the free chlorine level at the deep end of the pool.
i will do both of the tests you suggest to see if something is binding or burning up the free chlorine level


Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
Aug 10, 2012
FL panhandle
Welcome to TFP!

9 times out of 8 when people think their SWG isn't keeping up it is because there is algae growing in the pool. I think the best way to check is to shut off the SWG and use bleach to raise FC up to 5 or 6 or 8ish and do an Overnight Chlorine Loss Test.


Apr 6, 2017
Bokeelia florida
I did the overnight test. The free cl starting level started at 9.1 and this am the free cl is at 6.4 so I am going to do the slam treatment and see if that will cure the issue.
In regards to the water it is crystal clear but I can see tiny little bit of what looks like black algae in the grout lines in a few places just above the pebble finish.
Thanks for the help and I will keep you posted


Mod Squad
TFP Expert
LifeTime Supporter
May 11, 2014
Franklin, NC
The free cl starting level started at 9.1 and this am the free cl is at 6.4 so I am going to do the slam treatment and see if that will cure the issue.
I have a question and a comment.....

What are you testing with to get a 9.1 FC level?

Please understand that a SLAM is not a single "treatment", but is a process that can (and usually does) take days to complete.


Bronze Supporter
Jul 23, 2015
Mayfield, KY
I have the same system, with no problems so far. What is the size of your SWG, and how big is your pool? It would be helpful if you added all info into your signature line. Good luck!!


LifeTime Supporter
TFP Guide
May 14, 2015
Cartersville Ga
Just a quick note. A SLAM is a sustained process of testing and redosing chlorine until all three criteria are met. At the start of the SLAM you should test and redose as often as you can. Ever hour or so would be best. Once the need for redosing starts to drop, then you can extend the time between testing and redosing.

Use the poolmath button at the top of the page to help guide you with your redosing.

Here is the link to the SLAM process: Pool School - SLAM - Shock Level And Maintain

{Guess I'm the slow typist for today} :)


Apr 6, 2017
Bokeelia florida
Ok I started the slam and had no major drop in ft levels over weekend.
so with auto pilot shut off the Fc level drops about .25 over night and 1.50 during the day in full sun with water temp at 88+.
if I run the auto pilot for a 8 hour cycle the FC level drops at the same rate as without the auto pilot.
so it's safe to say the it is not producing enough chlorine.
my FC level and tc are exactly the same so cc should be 0
water is gin clear if I add 10% liquid to keep fc level a 6.0

what is the fourms suggestion on dealing with the manufacture as we are still only 6 months old?
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