Salt generator not producing enough chlorine

Aug 8, 2015
65
Jeffeson, MA
New pool (2 months) that has hayward aqua plus with t-cell-15 for up to 40,000 gal. I also have a nature 2 sanitizer for 25-35,000 gallon pools. My pool is about 26,000 gal or so. My understanding is that by using the nature 2 it allows you to run your chlorine generator below the usual 1-3ppm and you can, in-fact, run the chlorine generator below 1-3ppm (.5ppm) and still have adequate sanitization of your pool.

I was told that I should be able to run the cell at a much lower % (25% or so or even less) due to the assistance of the nature 2 and that will greatly prolong the life of the cell. For the past 2 months the readings for the salt generator have hovered around 3600ppm, but on my test strips they only register about 1200ppm. This has been pretty consistent. I do taste some salt when swimming and they did put about 18 bags or so in when starting the pool 2 months ago but I have read a lot of posts that say the Hayward aqua plus readings could be off.

My issue is I keep all of the chemistry readings perfect (ph 7.5, Alk 100, CA 200, and CYA on test strips read between 30-50ppm and read much lower on my LaMotte Color Q photometric tester...usually single digits). However, my pool is around 90 degrees and I understand that can artificially lower the readings due to the high temperature so I have not paid too much attention to CYA on photometric tester.

The water looks clear and blue there does not appear to be any algae, the sides have no scale or slime, however I am running my salt generator at 45% and still every few days the chlorine levels are dropping to .2 and below unless I superchlorinate at 100% for 24 hours. I have done this almost every 5 days or so and think that I should be able to run the generator lower and should not have to shock that much based on what was told to me when I purchased. The pump is normally running for 10 hours every day.

It is a back yard pool that does not have a ton of bather load, just kids and occasional friends 3-5 days/week. I want to find out if 1. the salt generator is working properly (does not seem like it would need to be serviced already), 2. that the salt readings are correct (3600 vs 1200 on the strips), 3. Some other issue that I am not aware of or missing? Any help as to what it could be would be much appreciated.

Thanks,
 
Welcome. You sure have been told a lotta "stuff"! So here's my take on it. We do not recommend the use of the nature system at all. It adds metals to your water that can discolor hair, liners, etc. and create stains. You should pitch those salt test "strips" as they are horribly inaccurate. Consider getting one of the Taylor K-1766 drop based kits for that. But bottom line, if your cell is happy with the level it "sees" that's what really matters. Only thing worse tested on a test strip is the cya level, Yes, there is a drop based test for that-see the comparison of the tests we recommend in Pool School. Your CYA should be in the rage of 70 to 80 for your pool too. This will help reduce your FC burn off. And 3 would be the minimum for Fc in your pool at all times. Not 1. I would not be surprised at all if you have a very low level algae bloom waiting to blossom with your FC dipping that low.
 
Welcome to TFP :wave:
I agree with woodyp, while the nature 2 "may" increase the life of your cell, what it adds in the long run creates other problems. If sized correctly for the pool an SWG should chlorinate a pool just fine on its own without shortening its expected life span.


The best use of an SWG is for maintaining normal FC levels and for occasional boost to compensate bather load. It's great when your away or can't(or too lazy:)) check chlorine levels regularly.

If you need to slam pool, it's best to turn it off and let liquid chlorine do the trick and then get back to SWG

If you don't have a salt test kit, the only strips that even come close our the Aqua chek (which I currently use) BUT, I mainly go off the salt level reading on my SWG. As woodyp stated if it's happy with the level, then that's good

I am not familiar with your CYA test equipment, but with an SWG, it's better to have your CYA between 70 -80 as the SWG seems happier there ;)


Hope that helps... and again welcome
 
Thanks for your reply. I have been using a LaMotte Q7 test kit to check the CYA levels and it has been registering really low (usually single digits) but the test strips were always showing around 50ppm so I thought it was ok. It makes sense that maybe the CYA is in fact low and the LaMotte was probably right and that is why the salt may be generating the chlorine but it is not hanging around. I added some stabilizer yesterday and will continue to check over the next several days to see if I can get it up to the 70-80 level you recommend as it sounds like that should solve that issue and hopefully I should be able to turn the cell down and still generate enough chlorine.

- - - Updated - - -

I purchased one of the recommended salt test kits yesterday so that I can get an accurate read on the levels. The controller is registering 3500-3600 but I want to check to make sure it does not need to be recalibrated. Thanks!
 
95% of the time that your SWCG isn't "working" and keeping your FC low is that you have an algae outbreak. the SWCG cannot create enough chlorine to stop the outbreak and kill off the algae, but it tends to just keep it at bay from developing into a full blow green pool. before you do anything with your SWCG, I would turn it off, raise your FC level to around 15 ppm and do the overnight chlorine loss test (OCLT), see pool school. this will tell you if your problem is algae or the SWCG.

your salt level is not affecting the output. if the level is in range and your SWCG is showing it generating, then its generating. only time salt levels affect your SWCG is if you are getting a low or high salt warning.
 
Dan,
Ok, I just checked numbers this morning after purchasing a Salt Kit as recommended and the salt level is 3800ppm according to the Taylor K-1766 kit, so it appears close to what the salt generator is saying around 3500-3600 or so. I have been adding CYA slowly the past couple of days as it was registering 0 on Lamotte photometric tester and now it is at 20. Otherwise the water is blue and clear. I did a phosphate test kit and (unless I did it wrong) it seemed to register hight 1500-2500 or so. But most of what I read says do not worry about phosphates, that you need to take care of algae first. Would that be better with shock or an algaeside? Other readings are as follows:

FC = 2.5
CC = 0
PH = 7.4
Alk = 100
CH = 220
CYA = 20
phos = 1500-2500?

What should I do now? Should I continue to increase the CYA to 70 or so (as recommended in pool school for a SWG)? Or should I shock instead with some liquid sodium hypochlorite to raise the FC to 15 or so like you recommended even though I have no CC? Am I shocking because you think I am on the verge of a major algae outbreak or do I already have algae? Also, probably a stupid question, but if I shock should I turn the salt generator off or to 0% first?

Best,

Darin
 
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I think you should raise the CYA up to about 40 ppm and let the swcg run on the percentage it's set at now and see if your FC rises. If it does, then you're possibly ok and don't need to SLAM. If it rises significantly, then you can raise the CYA up to the recommended range.


I would abandon the nature2 recommendations and keep your FC according to the FC/CYA chart.
 
Thanks, I have been adding a some every morning and night the past few days slowly as I read that it sometimes takes a week to get an accurate reading and I read that you do not want to go over. The pool is going to be covered for about 3-4 days starting this thursday. Should I be ok if I add CYA until then and keep checking. We are expecting heavy rain later today/tomorrow.

Thanks
 

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Thanks, I will try that and do a OCLT test tonight.

make sure you raise your FC level high enough for the test. 10 is ok, 15 is better. add the bleach in evening after sunset and test again 30-45minutes later when the pump has been running. make sure your SWCG is off. record your FC level, and then retest first thing in the morning before sunrise-ish. be VERY careful to measure to the exact same level of water in the tube for each test. your drop should be 1ppm or less overnight. if its more, you have algae in the pool and a SLAM is needed.

BTW, what test kit are you using?? I wouldn't mess with CYA until after you do the OCLT.
 
I'm using a LaMotte Q7 photometric test kit. I have to break up a CYA tablet in the test tube and then put it in the meter after a few minutes and it reads it electronically. I got the same numbers (20) that the pool store I took it to yesterday got...however they used some kind of strips to test, but I did not tell him what numbers I got and he got the same so I think we must be close. I did not have a chance to grab some liquid shock today so I can't do the OCLT tonight, but when I tested the chlorine levels tonight (after dark) the FC has climbed to 4.18 from 2.5 this morning with the same setting on the SWCG. Could I still do the test if the pump and the SWCG are off all night and I check the FC levels first thing in the morning before the pump kicks in even though the levels are much lower than the 10-15ppm that you recommended? If it went from 4 to less than 3 would that still indicate an algae problem?

Thanks,
Darin
 
Lots of problems have been reported from folks using that LaMotte tester and it seems you're experiencing some. Can you put it aside and get one of the two test kits we recommend- The Taylor's K-2006 (no other #) or the TF-100. Both are available via TFTestkits.net and the Taylor's can be found on Amazon or occasionally locally.

Both kits use drop testing so its pretty clear and very precise. Strips are worthless and too vague.
 
To properly perform the OCLT If the pump is off overnight you should start it in the morning and let it run about 30 minutes before you take the sample. That gives the water a chance to mix in case there are areas if low FC.

I'd let things settle a little and get the CYA right and get the setting of the swcg close before trying to run the OCLT. Give it a day or so and then decide if you want to run it.

It is important to have the swcg off during the OCLT.
 
Readings tonight as follows:

FC = 4.5
CC = 0
PH = 7.5
ALK = 100
CH = 220
CYA = 34

I reduced my SWCG from 55% to 40% over the past day and a half and the chlorine levels have been slowly climbing and maintaining as I have been slowly increasing my CYA levels. I did not have any FC loss overnight (stayed right around 4) while the SWCG was off....not sure that means anything as I understand a true OCLT needs to have over 10ppm to be worthwhile, however the water looks blue and crystal clear. At this point should I just continue on the path that I am going and get my CYA levels up to the recommended 70-80ppm and adjust my SWCG to the right % to keep my FC levels around 4 which seems to be the recommendation in the pool school? Or does anyone think I could still have an algae issue? I am covering the pool every night with a solar cover...not sure if that makes a difference.

Thanks,
Darin
 
If your CYA goes above 70 then raise your FC target to 5.

As was noted above, so,dr everyone who has posted they used a ColorQ eventually had issues. Most dealt with reliability/repeatability of tests. Just for giggles, test the same sample of water multiple times to verify your numbers are stable.

You asked a question before about shocking your pool. If you maintain the correct FC/CYA ratio then shocking is never necessary.
 
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