PLEASE HELP--Chemicals balanced but have algae

[aesweeps]

Hi. In April of this year we had our liner replaced in our in-ground pool. Water has been great up until last 2 weeks. Chemicals are balanced and readings are listed below, I use the Taylor K-2005 kit. I've been finding small patches of algae, not a lot but enough to know it's there and needs eliminated. I find it in corners or along the wall, and around the frame of the steps. I brush it all away and then shock it. Usually find it again 3-4 days later in corners and such. I had a little trouble in the beginning getting chlorine levels balanced, and aboout 3+ weeks ago I was having trouble getting alkalinity normal, it was a bit high at 150 but now is normal level. Hoping someone can offer suggestions on what I should do, and why algae is starting to grow. I always thought if the chemicals were balanced then no worries of algae. Pool details: 25,000 gallon vinyl liner, 2 skimmers, full sun--no shade. Not sure if any of this is needed but for chemicals I use: Arm & Hammor Baking Soda from Sam's Club (for pH add), Aqua Chem Chlorinating granules from Lowes which has Trichlor-s-triazinetrione: 71.8%, Boron sodium oxide: 8%, Other Ingrediets: 20.2%, Available Chlorine: 65%), and Aqua Chem Chlorine 3" tabs for in-line chlorinator. Thank you so much for any help that is provided. Anna

FC-2
TC-3
pH-7.6
Alkalinity-100
Calcium Hardiness-100
CYA-62

[Watermom]

I have no idea what Boron sodium oxide is or what you have used it for. But, I can tell you that if you have algae, then your chemicals are not balanced.

You need to shock your pool up to about 20ppm if you want to get rid of the algae. Chlorine levels are based on your CYA. More about this connection between the two in this chart:> http://pool9.net/cl-cya/

You have to maintain this shock level until you are able to go from sundown one evening to sunup the next morning without losing more than 1ppm of chlorine and you also have no more than 0.5ppm of CC. By the way in case you don't know, FC + CC = TC. So that means that you have a CC reading of 1ppm. Ideally, you want your CC reading to be 0.

With your kit, you aren't going to be able to measure chlorine readings past 5. But, if you buy the Taylor K1515 add on kit, that combined with the K2005 kit that you already have will in essence give you everything that the K2006 kit (that we recommend to everybody) has. Then, you will be able to measure high chlorine levels.
You can find the K1515 by going through this link that takes you to Amazon:> http://pool9.net/tk/ (The kit will not be available locally.)

In the meantime, go to Walmart and pick up a OTO/Phenol Red kit (yellow and red drops) and use this. The scale on this OTO kit also only goes to 5 but if you use the chart at this link, http://pool9.net/oto-chart/, you will be able to decipher what the colors mean when your chlorine goes past 5ppm. (Your current kit cannot do this as it will bleach out at high chlorine levels.)

Your pH, alk, and CH all look fine.

I would suggest just using bleach for your chlorine. No more chlorinating granules and no more tabs. Those products all have CYA in them, and your CYA is high enough.

In a 25K gallon pool, each 121-oz jug of generic Walmart 8.25% bleach will add about 3ppm of chlorine. You can use that to help you figure out how much bleach you add whenever you test to get your chlorine back up to shock level of 20.

Keep your pump running 24/7 while you are working to clear this and also brush the pool whenever the chlorine is high. What kind of filter do you have, by the way?

Hope this helps. Welcome to the Pool Forum!

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[PoolDoc]

@WaterMom: "Boron sodium oxide" is just a BioGuard name for borax . . . to make people feel like they are buying some thing special worth the price they (over)charge.

@aesweeps: To get rid of algae, you'll need to keep your chlorine level closer to 15 ppm . . . and you'll have to get the separate FAS-DPD test to add on to your K2005, so you can measure those levels. Stabilizer splits your chlorine in 'active' and 'protected' components. With your CYA and FC level, your 'active' chlorine is high enough to sanitize, but not high enough to kill established algae. Read the Cl-CYA page to learn more: http://pool9.net/cl-cya/. The testkit page links to the Taylor FAS-DPD add on kit you'll need: http://pool9.net/tk/

. . . membership upgraded.