FC steadily decreasing

[micloud]

Hi all,

FC has been steadily decreasing over the past month:
Today: FC 4ppm (CYA 60… maybe 50)
2 weeks ago: FC 6ppm (CYA 60)
4 weeks ago: FC 8ppm (CYA 70)

I’m running my SWG at 70% for 12hours a day (which seems like a lot), so it feels odd that my FC isn’t higher or at least maintaining. I have passed OCLT two nights in a row. About a month ago I did change my VS pump to a lower speed of 1750rpm. The pump used to be running at 2450 rpm, which is where the pool guy used to run it last summer, but after reading a bunch that rpm seemed excessive so I reduced it.

I’m wondering what is causing the FC loss. I’m still within a safe range, but I don’t want to wait until its a problem to figure this out.

My first thought is that the CYA has also been decreasing, would that be the cause? If I raise it up, will the SWG then begin producing more FC?

How about the lower pump speed? Could that be a cause? From what I’ve read it seems like other people run theirs even lower that mine, so it seems unlikely?

Could this be a faulty SWG? Its only 2 years old.


Thanks,
Matt

 

[ajw22]

Running your Truclear cell for 70% 12 hours will generate 3ppm of FC in your 13,000 gallon pool.

At 70% each 4 hours gives you 1ppm of FC.

Your pool can easily need more like 4ppm of FC in these summer months.

Run your pump for 16 hours a day to generate 4ppm or 20 hours a day to generate 5ppm. Find out what pump runtime increases your FC then lower the run time a bit.

 

[micloud]

Gotcha! Didn't realize the SWG needed to run so long. I've increased SWG to 20hrs/day to see if I can get the FC back up and will then experiement with the times. I'll bump my CYA back to 70 as well.

 

[pjt]

I've increased SWG to 20hrs/day to see if I can get the FC back up

If you need an immediate boost, use LC.

 

[Whynotme]

Only thing I can add is to find out what your salt level is. Some generators won't produce chlorine if salt levels are too low or too high.

 

[micloud]

Only thing I can add is to find out what your salt level is. Some generators won't produce chlorine if salt levels are too low or too high.

Hi thanks… How do check the salt level?

Also I ran the SWG for 20hrs yesterday and my FC has come up by 1ppm. Which seems like it jives with what ajw22 said.

 

[pjt]

How do check the salt level?

Your signature shows you have a TF-Pro Salt. Perform the salt test.

 

[cwswifty]

This is somewhat anecdotal but the last 2 weeks I’ve had my SWCG on the highest setting of the Summer (50%) to maintain FC levels. When is the “normal” UV peak in the Summer? Could there have been recent solar flares or something contributing?

 

[jark87]

One other suggestion, just for peace of mind. Do the Overnight Chlorine Loss Test. If your pool passes, you’ll know there’s not an organic issue with chlorine consumption.

Perform the Overnight FC Loss Test (OCLT)

The Overnight Chlorine Loss Test tells if the SLAM is finished or if you need to start a SLAM. This article says how to do the OCLT.

www.troublefreepool.com

 

[micloud]

Your signature shows you have a TF-Pro Salt. Perform the salt test.

Funny I've always wondered what those extra orange reagents were and always meant to look it up. I'm surprised that Taylor makes no mention of these in their test kit paperwork. Anyhow thanks for the recommendation, I'll will do this test later today.

 

[micloud]

@jark87 ...thanks yes I passed 2 consecutive OCLT earlier this week, so I'm good there thankfully (I had a successful SLAM a couple months back).

@cwswifty ...thanks per google looks like the normal UV peak for Los Angeles is in July. Last summer I had a pool guy (our first summer with the pool). He occasionally would dump some LC into the pool and never made any adjustments to our pump or SWG (he basically did nothing, best decision ever to cancel that service). So I'm learning the ropes this summer and am discovering that its totally normal to run the SWG basically 24/7.

 

[micloud]

Salt is low (about 2200ppm) and per Jandy Trucell ideal level is 3000ppm. Maybe it'll work more efficiently once I get the level up.

 

[wireform]

While you dump the new salt in the salt cell should be off 24 hours and supplement with LC for the duration.

 

[Whynotme]

While you dump the new salt in the salt cell should be off 24 hours and supplement with LC for the duration.

Why does it have to be off? I've never turned mine off when adding salt.

 

[wireform]

Because if undiluted salinity in the water gets by the cell it'll overheat so for the sake of your wallet we recommend off.

 

[cwswifty]

Why does it have to be off? I've never turned mine off when adding salt.

My Jandy manual says to make sure it’s off but my interpretation is that’s for initial startup only. Adding a bad or 2 during the season I do not shut off the SWCG.

 

[wireform]

My Jandy manual says to make sure it’s off but my interpretation is that’s for initial startup only. Adding a bad or 2 during the season I do not shut off the SWCG.

View attachment 604904

True for a bag or two but I then also do the following, empty way back in the shallow and also shut the main drain where gravity will pull it faster then you'd believe. I dropped my stirr bar in the shallow literally at the foot of the stairs in a fairly large pool and it disappeared and watched it take off all the to the to the MD in minutes. The salt will follow the floor too so just valve off the drain and you're good.

 

[Saturn94]

My Jandy manual says to make sure it’s off but my interpretation is that’s for initial startup only. Adding a bad or 2 during the season I do not shut off the SWCG.

View attachment 604904

I don’t see anything that indicates that this is just for initial startup. It’s great if you haven’t had any issues, but personally, given the potential risk to expensive equipment, it simply isn’t worth the risk. For me it is no big deal to turn off the SWCG for a short time for the peace of mind.

As a guideline for pool owners with such a wide variety of pool setups, I think TFP takes the correct position recommending the SWCG be turned off when adding salt.