Chlorinator not working properly

  • Last Post 15 April 2019
  • Topic Is Solved
Edward posted this 06 April 2019

Hi. Have had problems with chlorine levels all Summer. Last few years pool has been hassle free but not this year!

I believe now that the chlorinator is faulty - still producing chlorine but just at a much slower rate. It is self cleaning, we don't have hard water and no calcium buildup visible. As it is still producing some it has been hard to identify as I check the sunscreen levels, ph, salt etc... but I have now down tests in the evening with all levels good and it should produce about 2ppm over 5 hrs but is producing  about 0.4ppm. 

Any thoughts on this? Tips to confirm? All lights are healthy. The chlorinator is 2 years old.


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InyoRob posted this 08 April 2019

Hello Edward - The salt cells will begin to produce less chlorine as they start to fail. What is the make and model of your system?

Edward posted this 09 April 2019

It is a Zodiac LM2. Thanks for info - so could just be on the way out. Not great for only lasting 2 years but good to know a possibility.

I do however have a new theory that I would appreciate your thoughts on. Only thing that has changed since problem free pool is that we replaced the filter. This obviously means greater sucking power and it appears to be developing this vortex in the skimmer box which it means that it sucks air. Pump seems to cope with this and reprimes itself. Now, never had this problem before and I watch and keep the water level at minimum 1/2 way up the box level. But maybe with this new filter and extra suck I need to keep the water level higher???? If the vortex happening a lot obviously less chlorine produced. Thoughts on this vortex? Anything I can do other than raise water level? I read somewhere put a tennis ball in skimmer but how do I ensure that stays in. Any comments most appreciated. 

InyoRob posted this 09 April 2019

The vortex may play a roll in the lower chlorine output if the pump is constantly struggling to prime. A priming issue would result in a lower flow rate. If the flow rate were low enough, the salt system would kick off temporarily. Adding a couple of inches to the water level should eliminate the vortex. Do you have a weir door on the skimmer? A weir door would prevent the tennis ball from floating out.

Edward posted this 10 April 2019

Hi Rob, thanks for your reply. Yes, we have a weir door and so yes agree the tennis ball will stay in! Does it help the vortex issue? It seems that with the new clean filter there is now very little wriggle room with water level. Need to have at 3/4 height of skimmer box but not much higher or won't skim well but any lower this air vortex occurs! Any other solutions for this?

InyoRob posted this 10 April 2019

I've heard of the tennis ball trick but have never tried it. You shouldn't need to use a tennis ball. Can the weir door swing up and down freely? Sometimes they'll get stuck and that can create a vortex. 

Is the main drain pulling water? If not, open that up a little and that will take some of the suction away from the skimmer.

Edward posted this 11 April 2019

Hi Rob, as usual - thank you kindly for your time and assistance. Weir door working fine.

The main drain is closed - it doesn't have a filter or anything and so is it normal to open - won't it potentially clog up?

I think we now know the cause of the problem - we have a leak!! Last few weeks have been filling the pool more than normal but hard to tell due to evaporation and kids splashing but now watching it closely it is slowly dropping. So, now going through the process of trying to identify where it is.... and then call in a pro.

It doesn't appear to be in suction side as if the water is high the pump runs and no air enters the system. 

Next step seems to be to watch and see where the water levels out to. We have put on cover. 

Now, to find a competent professional! Wish we were in the US - your help and knowledge has been the best I can find.


InyoRob posted this 15 April 2019

Thanks for the update, Edward. It is normal to leave the main drain open. They are typically closed completely when you have a suction cleaner. The suction cleaner becomes the moving main drain.

Come back and let us know where you find the leak.

Edward posted this 15 April 2019

Thanks again. Leak found in outlet pipe for solar hot water heating. Very big job to fix properly - would need to lift up tiles and cut into concrete - have applied epoxy for now and leak has stopped. We barely ever use solar hot water and it is old style rubber one which is getting old. Thinking we might just fibreglass over the outlet holes.

Been watching closely and we were losing about 1inch per day with cover on. it was hard to realise we had a leak with evaporation and kids splashing... been having "troubles" with water cleanness for about a month and am guessing the leak has been there that whole time.