First tests w/TF 100 surprised me...

[hyperionguy]

Hi all,

I got my TF100 in the mail today. My initial tests look strange in the chlorine department.

PH = 6.8
TA = 50 (but isn't this the one that is affected by high FC?)
Hardness = 260
CYA = 60

FC = 13.5
CC = .5 (not too surprising I guess, there are a ton of acorns on the bottom for the last 4 days I have been gone) is this odd?

The chlorine strikes me as odd because I haven't shocked in the last 2 months. I have the newer Intex SWCG that supposedly puts out a lower percentage than the legacy units. My pool is 3,000 gallons and I have been running it two hours a day for the last 2 weeks (formerly 6 hours a day). I guess that explains my observation that during August when I was running it 6 hours a day I could actually smell chlorine when I sniffed the surface of the water.

Hmmm. Odd.

Any thoughts??

 

[dmanb2b]

Not surprising at all. With CYA at 60, your SWG should have no problem chlorinating a 3K gal pool. I use one (although the older model with twice the output) on our 13k gal pool and it only runs 3 hrs/day. I'm more concerned about your PH. PH tests falsely high when FC is above 10 and given you are at 6.8 with FC at 13.5 would suggest it is even lower...this also explains TA at 50, which is borderline too low, unless you are also running borates. I would let FC drop to below 10 and check PH again, if still low, it should be adjusted to 7.2 using borax.

 

[y_not]

Hyperionguy,

YAAAYYYY!! YOU GOT YOUR KIT!! WOHOOO!!

I feel that your TA is just slightly low, but maybe it's my interpretation of dmanb2b's prose.
For an SWG pool it's supposed to be 60-80ppm on TA to help reduce pH rise from aeration in the cell.

CH? Who gives a hoot, so long as you keep TA down.
Yeah, pH? Don't even remotely trust it with FC above 10ppm. pH only reads true at or below 10ppm FC.

I'm betting your FC is so high because of cooler water temps. Here in my neck of the woods, Central Oregon, with my pool temp running about 55-58 during the day, I'm seeing ZERO CL loss during the day on most days. It has taken weeks to drop from shock level of 12ppm down to 4ppm.
That leaves me with the question. What's your water temp?

Be careful /w the Borax, as it will also raise your TA. Using chemicals, you can't raise pH without also raising TA at the same time. I would add enough borax to bring your pool up by 10ppm TA, for a total of 60ppm. This will also raise your pH, but still undershoot it. Then aerate to bring pH up to where you want it and TA will remain the same, you could let the cell do this on it's own, or do it manually with a fountain or a return jet pointed to the surface. The proper range is 7.5-7.8pH for SWG pools. I'd shoot for 7.5, since it likes to climb.
The reason I'm suggesting the lowest numbers of each range, IE. the minimums. Because this way you can see how your pH behaves and whether it goes up or stays the same or close to it. If it climbs up on its own, then you haven't shot too high for either one. If it stays the same, then you're SET!!

It's easier to raise TA, than it is to lower it. It's very time consuming to do the latter, not to mention that once you add borates, it becomes much, much, much harder to lower TA!!
TA = Easy to bring up, hard & time consuming to bring down.
If you still get pH rise, you can always shoot for more borates. Just keep track of how much you add to raise your TA, then subtract that from your total when you go to do the full on borates addition.

 

[y_not]

<snip> I guess that explains my observation that during August when I was running it 6 hours a day I could actually smell chlorine when I sniffed the surface of the water.
<snip>

I should point out that the typical smell we associate with chlorine in a pool, is actually CCs instead. These are the byproduct of CL breaking down organics in the pool, it's CL molecules combined with ammonia molecules.

CC is bad, FC is good.
High CC's smell awful, they're an irritant and indicate the need to shock with bleach.
High FC when using bleach or an SWG to a slightly lesser degree smells sweet and fresh. Not irritating at all at most pool levels.

When I shocked my pool, about the same size as yours and had FC up to as high as 15ppm, I could sorta smell chlorine. But mostly I think it was the inflatable PVC ring.
When I'd take a sample, I couldn't even smell it on my arm/hand. What I did smell from the pool wasn't even remotely irritating, it was a pleasant smell.

 

[dmanb2b]

I feel that your TA is just slightly low, but maybe it's my interpretation of dmanb2b's prose.
For an SWG pool it's supposed to be 60-80ppm on TA to help reduce pH rise from aeration in the cell.

Hey y_not...sorry I guess I should have explained my position on that a little better....

TA at 50 or below can sometimes make PH unstable just as with high TA, unless there is an addt'l PH buffer such as Borates. Given this is a small intex pool, the SWG does not operate long enough as compared to a traditional SWG pool to create excess aeration/PH rise, so in my opinion TA of 50 is a bit too low.

Again, my main concern here is that PH may be even lower than 6.8, given the FC level is above 10ppm. Once FC falls below 10 and the OP adjusts PH to around 7.2, that should also raise TA some.

 

[y_not]

Sure, I understand. I just didn't want the OP thinking it was dangerously low at this point, about 17% at minimum.

I just wasn't sure whether you meant it was dangerously low, or just a bit but needed to come up.
We're on the same pg. though.

Dats all.

 

[dmanb2b]

TA is not dangerously low but I would not recommend running TA at 50 for this type of pool (17% imo is a fairly material deviation from our 60-70 guideline, but again that is only my opinion). PH at 6.8 is a problem and with FC above 10ppm it is tough to judge how severe.

My initial advice still stands, which after fixing the PH problem will also raise TA some:

I would let FC drop to below 10 and check PH again, if still low, it should be adjusted to 7.2 using borax.

 

[y_not]

I think it sounds like I'm actually completely disagreeing.
I'm really not at all.

pH low and inaccurate with high CL = Yes
Let FC drop to <10 or =10, then measure and adjust pH. Very IMPORTANT = Yes
TA low = Yes
TA Comes up /w borates to raise pH = Yes

When I posted that, I was likely thinking that the "low" moniker was based on std. TA recommendations for a non SWG pool. Assuming it was missed that the OP had one, or not thinking of the lower ranges for that application when your reply post was made.
Of course, totally missing the fact you're a mod and have like a gazillion posts and many years here under your belt. Oops.. DOH!
That 'borderline' is what threw my brain into a spin, made me think something else. IE. REALLY BAD! LOL
I'm too literal, which can have the effect of too extreme due to misinterpretation from over analyzing. haha!

Sorry bout that.

 

[hyperionguy]

Thanks for the input!

No Borates yet, but i've been researching it on TFP and I think I'll do it next year. Sounds like a fun experiment.

I don't have a pool thermometer yet. The weather is still in the upper 80s during the day and mid/lower 70s at night. So it is chilly water but not COLD. I still have it partially shaded with my 11' offset umbrella, usually used to keep the water cooler in the summer but used now to deflect a majority of the acorns falling right now.

I think I'll run the system in filter-only mode so there is no chlorine generation and let the ppm drop down to normal range.

Follow up question - if FC tends to hang at the higher level it's at now but my CC is not zero (.5 now), is the CC going to go away on it's own? I'm assuming that once i vacuum tree debris from the bottom and everything else is dead, it would fix itself.

 

[UnderWaterVanya]

Follow up question - if FC tends to hang at the higher level it's at now but my CC is not zero (.5 now), is the CC going to go away on it's own? I'm assuming that once i vacuum tree debris from the bottom and everything else is dead, it would fix itself.

Sure… as long as CC is only 0.5 and water is clear and you keep FC at or higher than the minimum FC level recommended the CC levels should remain at or below 0.5ppm.

Most of the time you are advised to treat CC of 0.5 or less as the equivalent of zero.

 

[hyperionguy]

Excellent!

Thx!

 

[hyperionguy]

OK, tested today. FC is approx 5, and PH is 7.1.

Still a little low, but not worth doing anything about.

Thanks for all your input!