SWG Installed - When to test for FC?

[rverette]

Before the pump starts? (looking for lowest level before replenishment occurs)
After the pump turns off? (looking for the highest level at the end of the cycle)

Some other time?

As per the Pool Calculator, the FC with an SWG should be around 3. So, I see a problem with measuring 3 just after the pump stops - it'll get pretty low before it comes back on the next day.

In contrast, If my goal is three just before the pump comes on, it must be higher than necessary from the night before.

So, what's the best time to measure?


Thanks.

PS: Pump runs about 10 hours a day.

 

[George N]

Mine is tested each evening after the sun goes down.

 

[RobbieH]

If you have the pump shut off at dusk, you should not lose FC overnight. That'd be the same as failing the OCLT! Mine runs from noon to 8 PM. Keeps my pool at about 4ppm all day. On weekdays I usually check my FC around 5:30 PM. Seems as good a time as any for me. On the weekend, I'll check it usually around 11 AM, which is before the SWCG and pump have fired up for the day. I've found little if any difference in my numbers.

 

[harleysilo]

Hi! Do you know what your CYA/Stabilizer level is?

It will take some trial and error for you to work out run time and the % at which your SWG is generating to keep chlorine at the proper levels. If you are going to run your pump on one continuous cycle for 10 hours, and then it stays off for 14 then I would measure your Chlorine levels before the pump starts. This way you know that your Chlorine is not dropping below the recommended level at your CYA ppm.

Personally i'm still experimenting with mine, currently I have mine set to run 4 hours total in 4 separate cycles.

 

[harleysilo]

If you have the pump shut off at dusk, you should not lose FC overnight. That'd be the same as failing the OCLT!

This is an interesting point. So people without SWG have to add chlorine manually every day the same as people with SWG's are adding chlorine every day. No without these additions at some point chlorine levels will fall. At what point is it failing the OCLT vs. failing to replenish Chlorine?

If nothing is in the pool is consuming chlorine, and it is dark out, you shouldn't loose any chlorine, right? What about if it's daytime and your have a good amount of CYA, will you still loose some or none (assuming nothing in the pool to consume it?

Should a SWG not be run at night then as it just adds chlorine that won't be used (assuming pool is free of algae and other organics) and lead to raising your levels above the recommended?

 

[RobbieH]

Yep, if you just add liquid chlorine, it is pretty much a daily job. That's why I put a SWCG on my pool! On a pool my size, I was carting A LOT of chlorine!

Daytime you'll lose FC just from the sun, even with CYA in the pool.

You can run it at night, but my opinion is it makes more sense to run it in the day when the sun is eating FC. Also that is usually when the wind is blowing pollen and such into the pool, so I'd rather run my pump then regardless of salt water or not.

With CYA of 70-80, your SWG probably won't take your FC to levels of concern even if run at night.

 

[bobodaclown]

I check mine in the AM usually before the SWCG kicks in. If I sleep in then I check it when I get up as long as it's in range I don't sweat it. I'll add a gallon of chlorine bleach if I'm having a party or heavy bather load as prevention. Otherwise I maintain at 4 PPM or greater.

 

[harleysilo]

Yep, if you just add liquid chlorine, it is pretty much a daily job. That's why I put a SWCG on my pool! On a pool my size, I was carting A LOT of chlorine!

Daytime you'll lose FC just from the sun, even with CYA in the pool.

You can run it at night, but my opinion is it makes more sense to run it in the day when the sun is eating FC. Also that is usually when the wind is blowing pollen and such into the pool, so I'd rather run my pump then regardless of salt water or not.

With CYA of 70-80, your SWG probably won't take your FC to levels of concern even if run at night.

Now to add one more twist...I keep my pool covered unless we are swimming, so basically it's nighttime all the time except for 1 hour or so on a weekday evening and several more hours on a weekend day. So I may be getting 10-20 hours or sunlight a week.....