Pool Nub

[PoolDoc]

Increase the number of drops of phenol red you use, and see if you can get a more definite color.

[Michaelam]

Started SWCG this morning before I left for work. When first started, it is programmed to run on "super chlorinate" for three hours. Got home this evening to crystal clear water, and was finally able to do a full test set using the K-2006. Here are the results:

FC: 9 ppm
CC: 1 ppm
TC: 10 ppm (Did a second check using OTO and came up with about 4 ppm) Up until this point, when I get home, there is typically 0 ppm Cl in the evening (left over from bleach add night before & no CYA)
pH: ~7.6 (1 drop of acid took it to ~7.4)
TA: 120 ppm
Hardness: 130 ppm
CYA: ZERO (hadn't added any at this point)

SWCG manual calls for the following:

FC: 1-3 ppm (I'm out of spec high)
pH: 7.2-7.8 (though the manual also says these pools tend to settle out around 7.8)
TA: 100-200
Hardness: 200-300 (I'm out of spec low)
CYA: 30-60 ppm (I'm out of spec low)

I used bleachcalc and came up with ~7 lbs CYA for a 30 ppm move. However, I only added 3 lbs tonight.

Questions:
1) My SWCG is oversized, I assume after tomorrow, I will need to dial it back somewhat. True?

2) Is the hardness level a concern? If so, what should I do?

3) If bleachcalc is correct, I should see ~15 ppm CYA tomorrow. Correct? Should I then make another add to slowly get into spec? Once I'm there (30-60), what is ideal?

Thanks for all the help. This site is great. I'm already getting glazed over stares when I tell people I'm using the BBBSWCG method of pool chemistry control.

[PoolDoc]

? #1 => Yes, turn the unit down as needed.

? #2 => Do NOT raise the calcium level, yet.

? #3 => Not necessarily, CYA can take several days to dissolve.

And, more:

4. Do try to run high CYA (~80 ppm) for most SWCGs; Do NOT try to run 1 - 3 ppm FC -- it's too low.

A number of guys are running SWCG systems with FC = 5% of CYA . . . but many of them (most?) are in western, or west coast areas that are dry and do not have the humidity, thunderstorms and the like that can leave algae in every bit of dirt and on every leaf. I'd recommend the higher levels you see in my Best Guess Chart (blue signature block).

[Michaelam]

Update:
After our first three days of use, here are my latest results from tonight:

FC: 6.8
CC: .6

pH: 7.6
TA: 120
Hardness: 130
CYA: ~55

NaCl: 4200

Chlorine is a little high, but I'm going to try the SWCG internal timer to dial back production at night. With the exception of hardness - recommended 200-300 - everything else is in spec. I've lost some water due to evap, splashing, etc, so I'm going to need to add soon. That will get my NaCl closer to the ideal 3500 ppm. What about hardness? What should I do to adjust? Any special concerns for making a water add - other than check chemistry after?

Thanks for all of your help - my pool and water are looking great! (The neighbor's kids have already abandoned their pool and parked in mine. lol)

[PoolDoc]

You may want to push your CYA higher -- SWCG's run a bit better at the recommended 80 ppm CYA. But do NOT follow the mfg's 1-3 ppm FC recommendation; instead use the 5% rule (FC = 5% of CYA, or 4 ppm with CYA=80) as an ABSOLUTE minimum. Alabama is more like Chattanooga (the 5% rule was tested more on the West Coast in dry areas, where there wasn't algae in every puddle and on every leaf!), so you probably want to use my Best Guess chart, which is somewhat higher.

I wouldn't worry about the hardness (CH) - just use borax to raise your pH if needed and do not use bicarb or pH up (soda ash, sodium carbonate).

[Michaelam]

Since the 25th I've run my cleaner 2X and programmed my SWCG to not run between 10P & 6A & NOTHING else. Pool has been used every day by 3-6 people. Here's the latest as of tonight:

FC: 6
CC: none detectable
pH: 7.6
TA: 120
Hardness: 150

Couldn't test for CYA because I ran out of reagent - the K-2006 only came with enough to test CYA 6X. Need to order more. At any rate, water is crystal clear, looks and feels great. Can barely even tell it's salt water - & there is no Chlorine smell. Based on previous advice, I want to get CYA up a bit, but other than that, I'm down to what I hope to be my last couple of questions for a while. Is it now possible, chemistry-wise, for me to program my pump to shut down along with the SWCG (10PM - 6AM)? Anything special to consider for doing so?

Again, thanks for all the advice - it's been a great help!

[PoolDoc]

I can't think of a reason not to go ahead and shut down the pump, too. Just remember to run it a few minutes AFTER you shut down the SWCG, to clear the lines.