Chlorine level hard to maintain

[Tmmeekins]

Hi - I'm not a new pool owner but as always, i'm running into new problems. I am having an issue (actually started last season) where i seem to continue and lose chlorine. I have a Fiberglass pool (36X16) that has a SWG system. I feel i'm pretty on top of my chemistry readings and use the LaMotte system to daily check my FC, PH, and ALK. I monthly check my Calcium and CYA. I also check my phosphates every couple of weeks because I understand that is something that can eat away at chlorine. Yesterday, for example, I tested my FC and it was just over 3 and my CYA was 59 - this was taken in the AM. No one swam yesterday and we didn't receive any rain. The PH was 7.4 and ALK was 74 so I did add in some increaser as well as added some CYA to try and get it up to 70. This AM I checked and it was down to 2.5 FC where my PH was 7.5 and ALK was 104 and CYA was 69. I added some reducer. Last week I tested my phosphates and it showed around 200 so I added some Phosphate reducer. Below are some other facts/things and I'm just looking for thoughts:

- I just cleaned my filter (cartridge (CS200)) and it was seemingly dirty. I do this about every month, or sooner if it seems I get a bit of air in my pump basket
- I currently have my SWG up to 90% which seems outrageous. I used to be able to manage my FC with no more than 40% or so running the pump at a slower speed.
- I run the pump around 2200 rpm 24 hours a day.
- when it was not as warm (in the upper 80's/low 90's in Richmond, VA this week) it didn't have an issue with generating or maintaining the chlorine so the heat def. has a factor, but I still can't figure out why i would need to even consider anything close to 100% (esp. when it still is not keeping up).
- Total Chlorine is always within .10 or so, which I believe tells me it isn't really working that much?
- I did add a couple pounds of shock over the weekend which took it above 5 for FC but again, it has been dwindling ever since.

Any suggesting or things to consider - i'm all ears. I am wondering if with a clean filter I might see some improvement?

Thanks
Mike

 

[Ibanezsvo]

i'm pretty new to pool stuff and you've probably already checked this but the one thing you didn't mentioned was inspecting the chlorinator cell. - have you checked it for scale build up? that could cause this problem.

 

[jedigrover]

1) How old is the SWG's cell? They don't last forever, and as they get toward the end of their life they tend to have less output--resulting in having to increase the percentage and it not keeping up the chlorine levels (doesn't matter what method you use to chlorinate, if the pool is exposed to air and especially light, chlorine will be consumed). The job of the SWG is to continuously generate chlorine to make up for that.
2) Don't chase pH and TA numbers. You don't have to micromanage it.
3) Total Chlorine is Free Chlorine + Combined Chloramines. So being within 0.10 is a good thing, as it means you don't have much in the way of organics actively consuming the chlorine. That doesn't mean that you don't need it. As I stated before, sunlight will break down chlorine (that's the primary reason for the CYA). If you don't maintain a good FC residual, any random algae and bacteria that comes into the pool will start growing. Just like you bathe everyday so the bacteria that lives on your skin doesn't make you stink, you keep the pool chlorinated to keep the nasties out.

My guess is your SWG cell is showing its age. With increased heat and sunlight, you have higher chlorine demand--regardless of bather load. It might not be able to keep up.

 

[Tmmeekins]

1) How old is the SWG's cell? They don't last forever, and as they get toward the end of their life they tend to have less output--resulting in having to increase the percentage and it not keeping up the chlorine levels (doesn't matter what method you use to chlorinate, if the pool is exposed to air and especially light, chlorine will be consumed). The job of the SWG is to continuously generate chlorine to make up for that.
2) Don't chase pH and TA numbers. You don't have to micromanage it.
3) Total Chlorine is Free Chlorine + Combined Chloramines. So being within 0.10 is a good thing, as it means you don't have much in the way of organics actively consuming the chlorine. That doesn't mean that you don't need it. As I stated before, sunlight will break down chlorine (that's the primary reason for the CYA). If you don't maintain a good FC residual, any random algae and bacteria that comes into the pool will start growing. Just like you bathe everyday so the bacteria that lives on your skin doesn't make you stink, you keep the pool chlorinated to keep the nasties out.

My guess is your SWG cell is showing its age. With increased heat and sunlight, you have higher chlorine demand--regardless of bather load. It might not be able to keep up.

Hey - thanks for the reply, and yes - that would have been good info to include . This is actually only the second season with the cell, so with it happening last year too I don't think it is the cell age. I actually contacted the manufacture last year to ask for help/suggestions and that is where the phosphates and such came from. I did go through the exercise of taking the cell out and putting it in a bucket - activating it and ensuring it was making chlorine, which it is.

Agree with all your other statements - i'm just still not sure why it requires such a long runtime of the cell (currently at 90%) to try and keep up. Not sure if 90% will or not, I'll find out in the AM I guess.

 

[Tmmeekins]

i'm pretty new to pool stuff and you've probably already checked this but the one thing you didn't mentioned was inspecting the chlorinator cell. - have you checked it for scale build up? that could cause this problem.

For the first time every, I actually took the cell out and stored it over winter versus just leaving it in. When I did that, I cleaned the cell (acid and heavy water stream) before storing. I have had the pool open only 5 weeks or so, so i haven't checked for build up but just going under the assumption that it should still be relatively clean from the pool closing and then storing inside over winter. I will def. check it out though.

 

[jedigrover]

So...
1) every time you acid wash a cell, you are also stripping some of the rubidium or iridium plating off and reducing the cell's life. Only de-scale if scaling is actually present. And then, use the weakest solution you can get away with. If you have scale, look at your CSI (saturation index) and adjust pool parameters to keep out of the scale-forming region.

2) What is your pool size (gallons) compared to what the cell is rated for? We usually recommend a cell size rated for 2x your pool size. The size ratings from manufacturers are for ideal conditions, not real-world conditions.

3) The pool product manufacturers have caught onto the phosphates game and use it as a boogeyman to avoid honoring warranty. We have good evidence from another post today that removal of phosphates does not magically help a cell that isn't keeping up.

4) What brand / model of SWG are we talking about?

 

[Tmmeekins]

So...
1) every time you acid wash a cell, you are also stripping some of the rubidium or iridium plating off and reducing the cell's life. Only de-scale if scaling is actually present. And then, use the weakest solution you can get away with. If you have scale, look at your CSI (saturation index) and adjust pool parameters to keep out of the scale-forming region.

2) What is your pool size (gallons) compared to what the cell is rated for? We usually recommend a cell size rated for 2x your pool size. The size ratings from manufacturers are for ideal conditions, not real-world conditions.

3) The pool product manufacturers have caught onto the phosphates game and use it as a boogeyman to avoid honoring warranty. We have good evidence from another post today that removal of phosphates does not magically help a cell that isn't keeping up.

4) What brand / model of SWG are we talking about?

Pool is around 14K gallons and my salt cell is a Jandy Aquapure 1400 which is rated for 40K.