Clear, but no chlorine???

[CarlD]

Dropping from 33 to 30 overnight? Perfectly normal! when you are super-shocking it's harder to maintain the FC...and you only dropped 9%. I wouldn't worry about that at all.
What I'm wondering is why your CC is so high and not dropping with FC > 30.

PS: I'd run the FAS-DPD test using the 5ml line instead of the ten. If you don't have that line you can either guess where it is or use a kid's med cup that comes with cough medicine with a 5 ml line. Each drop then is 1 full ppm rather than .5. It will take less time to do the test, use half the R-0871, and certainly be accurate enough at those high FC levels.

[BigDave]

I pretty much agree with CarlD, the FC loss is not such a big deal but the CC consistent at 3ppm.
Two questions:
How much bleach did you use yesterday?
Is there any chance that a bromine product has been put in the pool.

[mary jo]

OK- it was actually a 5ppm drop (35 down to 30). Did I wait too long to take the morning test? (should I test before sunrise ~ 6:00?) Yesterday is was overcast and rainy all day. This morning it's sunny.

I added 1 1/2 jugs yesterday. Yesterday morning's initial reading was 35 so I didn't need to add much to keep it at 30. I added the last jug @ 9:00 and tested at 11:00 and got 35.

Not sure what bromine is, but the only chemicals ever put into my pool this season: pH up (about 15 lbs), phos-free (1.4L) and 3" chlorine tablets for the inline chlorinator.

[CarlD]

It's still not a big change--if it dropped from 35 to 20 or 15 we'd be concerned, but from 35 to 30? That's OK.

Bromine is an alternate sanitizer to chlorine. It's more expensive, has a number of drawbacks, but is much more resistant to heat in hot tubs. It also doesn't "play well" with chlorine.

pH Up! is nothing more than Sodium Carbonate, aka Washing Soda, just overpriced.
3" chlorine tablets are Tri-chlor tablets--if they are 99% they are good. But for every 10ppm of chlorine they add, they add 6ppm of CYA/Stabilizer, plus push pH down.
Not sure what's in the Phos-Free, but I doubt there's any bromine in it.

Combined Chloramines can be all sorts of chloramines, not just the one bromine mixed with chlorine produces (monchloramine?) All kinds of things can be metabolized to form them, but guessing which one(s) caused the CC=3 is beyond me.

[BigDave]

1-1/2 jugs of 8.25% in 15,000 gallons is a daily chlorine demand of about 8ppm which still seems high to me.
I asked about bromine because bromine can create a permanently high chlorine demand.
I will put together another summary of this thread later today and ask PoolDoc or Richard to take a look.

For now, I'd maintain shock.

[PoolDoc]

Just checking in on this thread; obviously some good progress has been made.

But I have a couple of suggestions.

1. Unless you know of some reason not to do so, remove the Nature2 cartridge, even though it's old. ANY cartridge or filter media is a potential reservoir of accumulated oxidizable 'goo'.

2. For the same reason, clean the filter cartridges. Be sure to do it correctly. Spraying them off (with the hose; NOT with a pressure washer!!) is a good intermediate cleaning, but a full cleaning, which should remove any oxidizable 'goo' that could create chlorine demand takes more. See http://pool9.net/cart-clean/

3. It wasn't clear to me whether you ever inspected light niches or other recessed or hidden areas in the pool. If there are any such recesses, and if it's at all possible, inspect them. It does happen that such locations will fill completely with live 'slime'. Physical cleaning is required; otherwise, the slime will just 'recover' when chlorine levels drop.

Good luck!

[mary jo]

WOW- just checking in to ask about the Nature2 and cleaning the light niche…
to reply to your suggestions:
1. Nature2 cartridge: to be clear- remove old cartridge and clean the empty vessel? No way to remove the whole unit huh?
2. New Pentair filters installed a few weeks ago. Initial pressure set at 10, it is now 12. Strainer basket is clean and no debris.
3. My husband is home for the day: Should he clean the niches today or wait and see for a few more days? Don't think there are any other hidden areas: built-in ladder, built-in stairs, skimmers look clean, never much in them at all.
is there a youtube vid that shows the process of cleaning a niche (besides turning off the circuit breakers)!

I also took a look in the auto pool cover "pit". Removed the incredibly heavy concrete cover pads to find just a little wet/dry debris (mostly leaf pods). No funky smell or dead animals... The pit only goes down about 8" before you hit gravel backfill. Poured and wiped the cover with diluted bleach water as is was rolling up and unrolling.

the lawn guys were here and i closes the cover to see if any grass/debris was getting onto the cover. I don't think it is: the pool's elevation is much higher than the grass area: 5' drop on one end (foundation wall) and 45 degree slope to grass on the other.


btw: How do you remove and clean the lights when the FC is 35? You can't safely go into the pool at that level, right?

[PoolDoc]

35 ppm is not dangerous to people at all. With a CYA level = 150 ppm, 35 ppm FC is LESS aggressive than pool water that has 1 ppm FC and no CYA! (There is a difference -- 1 ppm FC will be used up rapidly by swimmers in the water; 35 pp will not. The 'extra' held by the CYA will continuously replace the 'active' chlorine as it gets used up).

But, it *may* be 'dangerous' to some swim suits, so wear an old one. It will also be somewhat irritating to your eyes, but, when trying to open the light niche, it would be best to use goggles or a mask regardless of chlorine level. In most cases, there's a single screw that needs to be removed to allow the light niche to 'flop' out.

This video, from Inyo pools, comes closest to showing what's involved. Obviously, you don't need to focus on the bits about actually replacing the bulb or lamp.

[mary jo]

OK- watched the video. Seems like it's something I need to do. I'm assuming that any slime or goo I find will have a color? Meaning that if the niche is not covered with visible goo, than I just need to wipe it down and re-assemble?
Good to know that high FC levels won't melt your skin off or anything. I've got an active imagination where chemicals are involved….

[mary jo]

Yesterday @ 5:00 pm my husband cleaned the light niches: One niche and light fixture perfectly clean. The other had a very small amount of brown stuff in niche and on fixture- wiped w/ a white cloth, let everything soak for 20 minutes before my husband had to leave town. I then scrubbed the skimmers again. Don't know if it's important but for first time ever I noticed a thin ring of solid black at the very top of the water line in both skimmers. It looks and feels like black grease, but wiped off w/ chlorine and cloth. hope this does something…anything else to clean or check?

overnight numbers:
last night - tested @10:00pm FC=33 CC=3
this morning - tested @7:00 FC=33 CC=3