Starting resurfaced pool

Great info PoolDoc!

2) So with all forms of chlorine adding some salt, no need to worry about rust with bleach then ;-) Re CYA biodegrading, I will keep an eye on it anyway and can add as needed. I just don't expect much loss if maintenance of FC level prevents slime.

3) To evaluate the LSI, I have so far used the watergram wheel in the K2006C kit *and* the water temp provided on the display of my Hayward H400FDN heater. I wonder what this temp really corresponds to now that you're mentioning this. I believe it is really close to what the temp is in the pool. Based on your explanation, I understand I only need to adjust the temp reading at the heater by +20 when it runs. I will take a look at the LSI calculator.

Re vacation/away time, I found a procedure about this on the Super Simple Startup Recipe page that does use polyquat. I guess this is what you were referring to. Interesting.

Re protozoan cryptosporidium, I found the procedure apparently from the CDC to fight it at this link: http://www.floridahealth.gov/healthy...ponse_reco.pdf

2) You could take it that way, but it's not what I meant. ;)

3) The LSI value that matters, with respect to your heater, is the LSI of the water 1/32" of an inch away from the interior of your heat exchanger pipes . . . and yes, THAT water will be at a higher temp than your pool water.

4) I'm working a vacation page. Polyquat can be a helpful tool with any approach. Basically, your options (which can be combined) are: use a feeder, use a floater, use an SWCG, use polyquat, maintain borates > 60 ppm, maintain phosphates < 100 ppB, follow HiC2 (high CYA + high chlorine) and raise FC > 30 ppm before leaving, cover your pool.

The crypto guideline has been updated since I last saw it. It was amusing to see how closely it aligns with what I tell guards: "It's not the nice t##d that will make everyone sick; it's the disappearing brown cloud!". Then, I usually 'share' with them information about a black bear's first meal after hibernation. S-)

PoolDoc:

2) Not sure I understood you. Do I need to worry about the salt that bleach adds and/or disappearing CYA?

4) I'll be glad to read your vacation page. Hope I don't miss it especially since I'd like to learn about borates and phosphates. That Phosfree product at Leslie's really has me wondering what benefit it could have....

5) I have CC and its level could rise. How do I get rid of it? increase TC 3 to 4 times my FC reading or in some other way?

If there are more current guidelines re crypto, it would be great to know even if there are no bears in sight here 8-D

Actually, the BEST way to manage the risk of crypto in YOUR pool is to keep anyone who's feeling a bit loosey-goosey S-) out of the pool. Instead, send them to the bathroom with a magazine and a bottle of loperamide (plug-em up) pills. :puzzle:

Over the past week or so, I have used seven 1lb bags of dichlor and things are looking pretty sweet around here. Chemicals are in balance but I have a question.

My CYA is now in the neighborhood of 30ppm and my TC at 3ppm (or 4) after I add dichlor at dusk stays there until the morning and drops to 1ppm after a long day of Texas sun.

Can I expect TC to drop less if I raise my CYA to 40ppm as Watermom recommended and even less if I raise it to 50ppm? (Right now with CYA at 30ppm, I believe I would need to add ~6 cups of 8.25% liquid bleach every day to bring TC back to 3ppm at dusk on an ongoing basis and it would obviously be great to have to use less bleach.)

As CYA increases, so does the half-life of chlorine in the pool. With CYA = 0, the half-life in clear shallow water is as little as 15 minutes!

However, the effective life of chlorine seems to go up as CYA increases, even when you maintain a constant available unstabilized chlorine fraction. For example, a pool with CYA = 20 pm and FC = 1 ppm has approximately the same available unstabilized chlorine as a pool with CYA = 200 ppm and FC = 10 ppm. But reportedly it takes MORE chlorine to maintain the first pool at 1 ppm, than it does the second pool at 10 ppm, assuming equal gallons, loads, sunlight, etc.

That's really something I need to experiment with.

Ok PoolDoc, so I should go up to the max recommended 50ppm CYA and expect to see chlorine last longer while initially having to use more to bring FC level not back to 3 but to 5ppm i.e. 10% of CYA level as per your target range earlier in this thread (which also happens to be the max recommended by the National Swimming Pool Foundation CPO Handbook Water Chemistry Guidelines I saw page 44 in the little guide that came with my K2006C).

I then hope the 5% FC bottom target (2.5ppm) is reached at least 2 days later this summer or more than 2 days when the sun is less of a fixture the rest of the year. At today's bleach prices (min 2.2c/oz in my area), there is a strong incentive to make it last as long as possible as it is more expensive than using trichlor tabs (was ~$99 a year though I was not necessarily on top of chlorine levels as I plan to be now and my CYA levels often went through the roof meaning algae).

Please ignore the CPO guidelines -- the info here is *much* more up-to-date. Chem_Geek, who started here in 2000 or 2001, has repeatedly tried --without much success -- to get the NSPF (behind the CPO) and the NSF to update their standards to reflect the work of Obrien (1972, I think) and Wojitowisc (circa 2000) and his own extensive analysis published here, on his personal home page, and elsewhere. (Wojitowisc' journal article in the JPSI was what gave me the confidence to publish my own observations in the first Cl-CYA page, which I called the "Best Guess Chart".

At this point in time, I'm pretty confident that Chem_Geek knows more about pool chemistry, from an comprehensive analytical view, than anyone else in the world. (Ernest Blatchley at Purdue is doing great work, but doesn't know about pools overall.) Add to that 10,000's of pool owners confirming not only my Best Guess chart, but Chem_Geek's analysis . . . and the CPO and NSPF are decidedly 'behind the times'.

But, given the fact that 'doing it right' would cost the pool industry literally $100,000,000's per year, their incentive to 'fix' things is small! ;)

Ben:

Very willing to learn based on updated info!!!

1/ "Wojitowisc' journal article in the JPSI" seems to be what I found at jspsi.poolhelp.com/ARTICLES/JSPSI_V5N1_pp20-38.pdf and the table on chlorine is indeed informative though not very legible. Your best guess chart reads much easier ;-) Any pointer to "Obrien (1972, I think) and Wojitowisc (circa 2000) and his own extensive analysis published here" (I could not find this)?

2/ Do you or Chem_Geek have a page summarizing updated recommendations kind of like what is on that page 44 of the Taylor guide but updated?

Thank you!

Simpler:

When everything is fine, no algae is present, and the bather load is light, FC = 5% of CYA (0.05 x CYA ppm = FC ppm target).

Under heavier load, 10%

With green algae, 15% - 20% or -- long term -- to remove black algae.

Mustard algae, 25% - 50%

With borates > 60 ppm, and especially, with phosphates < 125 ppb (0.125 ppm), the algae treatment levels can be lowered.