I'm going back to the pucks!

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C3Cl3N3O3

C3Cl3N3O3

0
Bronze Supporter
May 25, 2015
460
Fort Mill, SC
Pool Size
20000
Surface
Vinyl
Chlorine
Liquid Chlorine
Hehe well sort of. ;)

So my pool was a disaster last year with a CYA over 200 all all sorts of issues. Right in the midst of all that, my Hayward chlorinator got gummed up and quit working. So I changed that out to a Pentair myself late in the season, and around the same time discovered the TFPC method and changed over to that this year. So I did a partial drain and refill and got the CYA down to 40 for the start of the season (it was 80 when I closed but that's another subject...)

So this year things are going well. I just checked my numbers (Taylor 2006), and here they are:

Gallons: 20000
FC: 5
CC: 0
CYA: 35
pH: 7.8
TA: 80
CH: 50

The water is crystal clear. So I used to fight with acidic pH, and now it slowly floats up. It will float up to 7.9/8.0 and I'll have to do dry acid every few weeks or so, quite manageable. My plan is to run Trichlor only when I'm traveling for work, which is occasional. However, I've never actually run the Pentair for very long, so I don't even know where to set it to. I know my daily chlorine demand averages right at 2 ppm. So my plan is to run the chlorinator for 1 week with no liquid bleach to accomplish the following:

1) Find a decent chlorinator setting that will maintain chlorine for a week. Heck, find out if the thing even works.
2) Bump my CYA back up to 43 (35 + 2 ppm * 7 days * .6 ppm). My pool gets no shade and has a light swimmer load. I feel 35 might be a tad low, if I could get my chlorine demand down to 1.5 ppm / day that would be great.
3) Pull the pH back down

Hopefully this is a good plan. I think it's easier to adjust a chlorinator when everything is dialed in already with no excessive chlorine demand issues going on.
 
That IS a good plan. TFP is all about understanding how to MANAGE your pool water (not letting the part-time help at the pool store manage it) and that is exactly what you are doing.......testing and knowing what to do with the test results. Very nice work. :goodjob:
 
OK so after 10 days of the trichlor experiment, I have my results:

FC: 5
CC: 0
CYA: 35
pH: 7.3
TA: 60

I tried to measure the CYA as accurately as possible, going back and forth with the comparator and dispensing bottle a few times. It seems to still be right at 35, and didn't budge since the start of the test. This is a disappointing result. I used 6 pucks total (8 oz each), which should equal 10 ppm CYA rise for my pool. I know it is difficult to measure CYA accurately, but this should have moved the needle. Hmm.

EDIT: Also, the pool was not refilled or backwashed during the test.
 
Where did you get your pucks from? I got some from Sam's Club and they barely raised my CYA level. I have approximately 23,000 gallon plaster pool and CYA level was 30. After adding about 10-15 lbs of pucks, my CYA level only went up by 10. Pool math shows it should have gone up by at least 30.
 

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They are Aqua Chem Tabs Plus (3" x 8 oz). Since they eroded at nearly the exact rate predicted necessary to dispense 2 ppm FC per day, I can rule out "bad pucks". Unless these are magic "low CYA" pucks. Wouldn't that be nice.

- - - Updated - - -

pabeader said:
don't forget, it takes a week for the CYA to show. After it has gone into the pool.
Click to expand...

Is that really true in this case? I'm aware of that for solid stabilizer granules that take a while to dissolve. I wouldn't expect there's a bunch of undissolved CYA in my pool after running pucks for 10 days though.
 
I do the same thing whenever my CYA drops to 30. With our torrential tropical rains, I have lost 40 CYA this season already just from draining to waste extra water. I really find maintaing my pools fc is easiest at a cya of 60, and I don't have a swg. Mine is using pucks this week too.
 
pabeader said:
don't forget, it takes a week for the CYA to show. After it has gone into the pool.
Click to expand...

That's only when you add pure CYA through the skimmer to get caught in the filter because then it takes a lot longer to dissolve, especially in oversized cartridge filters. CYA added from Dichlor, Trichlor, or liquid CYA (sodium cyanurate) should register almost immediately after mixing in the water though with pure CYA if you use too coarse a sock, panty-hose, or T-shirt then granules could fall through away from a return or skimmer flow and those granules will take longer to dissolve.

I've used Trichlor pucks to slowly raise the CYA and it measures as expected though it's easier to see a 20 ppm change than a 10 ppm change. Of course if one has water dilution then one won't see much change.
 
Out of curiosity, what was the setting that you used on the Hayward chlorinator to add 2ppm? I have a pool size/ chlorine demand similar to yours, and at some point I will need to us my Hayward chlorinator for going out of town, and I have no idea what setting I would need....I'm just looking for a starting point and tweak it from there.
 
440dodge440 said:
Out of curiosity, what was the setting that you used on the Hayward chlorinator to add 2ppm? I have a pool size/ chlorine demand similar to yours, and at some point I will need to us my Hayward chlorinator for going out of town, and I have no idea what setting I would need....I'm just looking for a starting point and tweak it from there.
Click to expand...

The 3.75 setting seemed to do the trick. I assume yours is bottom fed, the same as mine. All bets are off with the top-fed installation.
 
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