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Thread: Beginner's Guide to Pool Chemistry Needs

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    Watermom's Avatar
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    Exclamation Beginner's Guide to Pool Chemistry Needs

    I copied this from a post made by a fellow moderator - CarlD. Very good information in a nutshell of the basics behind what pool chemicals are needed in a pool and why. It was originally written as a reply to someone about to install an above ground pool, so some of the info is aimed at caring for a vinyl pool. However, most of the info is relevant for all types of pools. Great post, Carl!

    OK, the BEST and fastest way to get up to speed is to go to the sister site, and start reading. Click on "Site Map" and go to the section marked "Info From Pool Solutions" and read everything there. No joke. It's very interesting and informative and will give you a wonderful foundation.

    All the chemicals and shorthand gets confusing. The idea is to keep your pool sanitary by killing all the algae, germs and viruses in it, and to keep its chemical level not too acid and not too alkaline.

    These 2 things, Chlorine(sanitation) and pH are the keys to pool care. Everything else is to keep them correct.

    pH is from high school chemistry--1 is super-acid (think pure hydrochloric or sulfuric acid). 14 is super-alkalkine (think pure lye). 7 is neutral. We want just slightly higher than neutral--7.3-7.8

    We lower pH if it's too high with acid--Muriatic Acid (Hydrochloric Acid) or Dry Acid (a powder). You can get Muriatic Acid at most hardware stores.

    We raise pH if it's too low with ordinary 20 Mule Team Borax which you can find in a green box in the laundry aisle at Walmart. You can use Soda Ash as well (sodium carbonate -- called Washing Soda) but it will raise both PH AND alk. If you only want to raise the PH, use Borax.

    Chlorine is our sanitizer. It kills algae, bugs, germs, viruses and is the ONLY sanitizer you should use for fecal matter. It also gets rid of excess suntan lotion, and other stuff. Our BEST way to add chlorine is with good, old LAUNDRY BLEACH! Yup, plain, unscented bleach is the best.

    We measure chlorine in our test kits. Sometimes they test "chlorine". This is actually Total Chlorine--the TC you asked about. Our better test kits test for Free Chlorine (FC) which is the stuff that does all those good things. The better tests also test for Combined Chlorine or Combined Chloramines--CC. This is the used-up chlorine that smells like disinfectant and irritates eyes. Its presence means you are metaboliziing something.

    TC = FC + CC. This is always. If you know 2 of the 3, you know the third. Test strips measure TC and FC, but not CC. Sometimes the TC is lower than the FC--that means the strip is no good. Generally, a good FC is 3ppm (parts per million). A good CC is 0, and a good TC is also 3ppm. But, how much chlorine your pool needs depends on what your CYA level is. See the sticky called "Best Guess CYA Chart" in the "Using Chlorine and Chlorinating Chemicals" section of the forum for the correlation between chlorine and CYA. If you don't use the appropriate amount of chlorine based on your cya level, you're going to have algae problems.

    Other tests are Total Alkalinity (TA or T/A), Stabilizer (CYA or Cyanuric Acid or Conditioner), and Calcium Hardness--Ca or CH.

    There are lots of other tests--TDS, SI, Acid Demand, Base Demand and they all sound important. They aren't and, unless something REALLY strange happens, you never, EVER have to think about them.

    Of the three TA, CYA, and Ca, these are important.
    TA, Total Alkalinity, is a measure of how well your water can keep from changing its pH. We like to see this be between 80 and 125 ppm. HOWEVER, in a vinyl pool it doesn't matter if it goes to 180...only past 200ppm does it become a problem. We raise TA with Baking Soda--good old Arm&Hammer. Lowering it is a pain in the patoot.

    CYA is stabilizer. You need this to keep your chlorine from breaking down too fast and leaving you with none. You have to buy this at the pool store. Aim for 30-50ppm Add less than you think you need because the ONLY way to lower it is dilute it by draining off water.

    Calcium Hardness is virtually irrelevant for a vinyl pool. But pool store guys will swear on their saintly mother's life that you need it for your vinyl pool. It's simply not true and is a waste of money. Calcium in the water prevents the water from sucking calcium out of concrete, plaster, or tile walls. It is not an issue in vinyl pool. It only matters to you if gets EXTREMELY high--500ppm.

    That's about it: Chlorine, pH, Total Alkalinity, and CYA are what you need to control. We use bleach, Borax, baking soda (the 3 Bs), muriatic acid and CYA/Stabilizer. You only need to buy CYA at the pool store--the rest can be purchased anywhere.
    Last edited by Watermom; 05-27-2010 at 10:06 AM.

  2. #2
    CarlD's Avatar
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    Default Re: Beginner's Guide to Pool Chemistry Needs

    I was asked to make a sticky out of this, but it's really just a re-statement of what I wrote in the post above. However, it may be a little clearer to some people....I suppose it would be best to rewrite them both, but I'm too lazy for that! Anyway, I hope this helps...Carl.

    it really isn't that hard. Once everything is in balance, you'll probably need to add some bleach every other day--probably between a quart and a gallon, but how much, I cannot say.

    It all seems SO confusing but it's not. There's two things that matter: Chlorine to sanitize your water, and pH to ensure it's neutral and not too acidic and not too basic.

    All total alkalinity is for (and the name is misleading to the laity) is it's a buffer for the pH--it keeps pH stable and from bouncing. You need it, but too much is a problem

    CYA/Stabilizer's job is similar, but for chlorine. It's a buffer that keeps chlorine from breaking down too fast, especially when exposed to sunshine (without which summer isn't summer). You need CYA, but too much is a problem

    Calcium is for concrete pools, not vinyl ones. It saturates the water with enough calcium to prevent it from leeching out of the concrete or plaster. Not an issue with vinyl. It's only a problem if it's too high.

    Other stuff: Most if it you should NEVER need if you follow the procedures discussed here.

    There's algaecide--most are copper or ammonia-based or foam and we recommend you NEVER use them. The only algaecide we recommend (and only as a preventative) is Polyquat 60%.

    There's clarifier and yellow-out and flocculant--(Polyquat
    acts like the last but otherwise most of us NEVER use these)--and pool stores push them.

    There's sequestering agents--this is only if you have problems with metals--maybe one in 100 of our members EVER need this--if that many.

    There's phosphates and phosphate removers. This is the pool store biz's latest scare tactic to sell you very expensive removers. Forget about it! Unless EVERYTHING we suggest here doesn't work, AND you have very high phosphate levels, that may be your answer--I can think of maybe 2 or 3 cases where it WAS necessary in the last 7 years.

    Finally, there's the chemicals you use. You can keep your pool indefinitely sweet and clean using the BBB's--Bleach, Borax and Baking Soda. Add to that Muriatic Acid and CYA(stabilizer) and that's IT!!!!!!

    But there's a catch--you have to have a good test kit, and use it regularly. We recommend something like a Taylor K-2006 kit as it can handle pretty much all the testing needs. In a pinch, a cheaper 5 or 6-Way test kit from Walmart will do. But, in the long run, investing in a better kit will pay for itself many times over. Regular testing will ensure that your pool has sweet, safe, clean, BEAUTIFUL water.

    Go to PoolSolutions.Com and start reading. Read EVERYTHING--then read it again...I went from totally lost 7 years ago to always having a "happy" pool. I was confident enough to go from a 4,000 gallon Intex 15' round donut (which doesn't owe us a dime from all the fun we had in it) to a 20,000 gallon 40x16 custom FantaSea with built-in, "invisible" solar heating. I credit and this forum for my education.
    Last edited by Watermom; 05-27-2010 at 09:56 AM.

    16'x40' rectangle 19K gal AG vinyl pool; ; Hayward T210 sand filter and 2 Speed Superpump 1hp pump; Solar heated. Test kit: PS 233; PF:6.3; Autopilot SWCG

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