Help, even bleach disappears

[bcrumb]

I have read many posts about shocking to kill algae and ben's best guess chart. I have tried to follow it but I can not get chlorine to stay in pool.
28k vinyl
FC 4(after using 17 Gals 8.25% bleach over past 2 days, plus 15 or more bags shock)
CYA 70
TA 100
ph 7.4
Goldline SWCG
All this year I have had to supplement with chlorine. Since I am a 12 year SWCG user, it is difficult for me to remember to add chlorine. Like I said, I have added 17 gals before today 9added 4 more today and 4 bags shock as well. Have not made new reading yet but so far, the highest I could get the reading was 12 and that did not last long. I saw new algae starting to grow at the base of the liner today even after the 17 gals of bleach. I am thinking that I have had an algae problem all year but was able to stay one step ahead of it and keep it from getting bad enough to see. Then I went out of town for a couple days and when I cam back it was growing everywhere although the water was not green, just cloudy. That is when I started adding the bleach, setting my goal at 20 ppm. Only I never can get there. The most I added at one time was six gals and a few bags of shock. Is my problem that I still have enough algae to destroy the chlorine I keep adding? Is it simply that I should have added enough to get to 20ppm all at once no matter how many it took? It is difficult to buy that many at once and scary to put that many in the pool at once. PS. for years, even when the water is clear and the pool looks good, I always have black or dark green algae in the grooves of the liner clips around the steps. Is this normal? I have to get a stiff bush mounted on an extension to get the stuff out of the clip grooves but it always comes back. Oh, yes and I have had to backwash de filter twice in past week. Today, I took it apart and cleaned it out really good, just in case any algae was hiding in there.
Update, after adding 4 more gals bleach today and 3 bags shock, I finally got the chlorine to read somewhere between 16 and 20. Hopefully I am on the right track now. How long do I need to keep it at this level?
Any advice will be greatly appreciated,
Brent

[CarlD]

First off: What are you testing with?
How big is your pool? Cannot estimate how much chlorine you need without that.
What is the ingredient of your "shock"? We HATE using "shock" as a noun rather than a verb here, because as a noun it can be ANYTHING--Cal-hypo, di-chlor, tri-chlor, lithium, "non-chlorine shock", sodium hypochloride. These things all add chlorine (except the non-chlorine) but add other stuff as well.

Plus, if you have algae, you have to kill it before the chlorine level can be maintained.

[bcrumb]

Sorry Carl. I tried to give all the relevant info. I did say 28k vinyl. 28000 gallons that is. Also the bleach 8.25 percent sodium hypochlorite from walmart. The shock is from walmart as well "pool essentials" and is trichlor. I am testing with the Taylor kit as recommended here, don't remember the exact numbers of the kit, but uses 5 drops 0001 and 5 drops 0002. You know the one that turns pink rather than the cheaper ones that turn yellow.

[CarlD]

Sorry, missed the first part.
What you are describing is a DPD chlorine test kit, vs an OTO test kit. DPD bleaches out at above 10ppm but usually around 15, but maybe sooner. The DPD Taylor kit is K-2005, not the K-2006 that we recommend. The difference is that the K-2006 uses the FAS-DPD chlorine test, not the DPD test. FAS-DPD can test to 50 or even 100ppm, and uses a powder first, then a liquid in a brown opaque bottle. The powder is, R-0870 and the brown bottle is R-0871.

If you're throwing in bags of Tri-chlor powder then I'll bet your CYA is now far higher than 70ppm. Trichlor adds 6ppm of CYA for ever 10ppm of chlorine. Stop using it. Don't use Di-chlor powder either.
If your Calcium level isn't too high, you can use cal-hypo--but the WalMart stuff is 48%--worthless. You'll need something over 60% or more.

So...Here's what I am GUESSING is going on
1) You're bleaching out a DPD chlorine test
2) Your CYA is now much higher than you measured, meaning, your chlorine isn't anything close to shock level for the CYA level.

Somewhere around here we have a key to the darker colors of the OTO (yellow) test kit. If you have an OTO kit, using distilled water you can double, triple or quadruple its range. And if it goes to "5" for chlorine, that means you can measure to 10, 15, or 20ppm.

Just mix equal amounts of pool water to distilled (I like to use a shot glass) and mix. In the OTO test if it says "5" it is now 10. If you mix 2 shots of distilled to one of pool water, "5" means 15. 3 shots--20.

[bcrumb]

That is what I was doing with my test kit. I took 4 ounces of pool water and added 12 ounces of tap water from the faucet (I know should have used distilled). Then I tested it to read around 4. Multiplied the 4 times 4 and translated that to read 16. Does this not work with that type kit? Even if I use distilled water? What about Kroger purified drinking water? I do not have the OTO test kit. I would be more likely to order the reagents you described above. Where can I get cal hypo?

[CarlD]

I don't know that dilution works with the DPD test. And, you should test the tap water FIRST before you use it to dilute...if it has a chlorine level it will add it. Same for the Kroger water.

Distilled water is sold in every grocery and chain drug store, so it's easy to get. Also, OTO kits are sold just about everywhere. But the BEST that is sold in retail stores is at Leslies--it's Taylor's own OTO kit, in a Leslie box.

Another really good one is the HTH 5-way drop test kit sold at WalMart (may be called a 6-way drop test kit now). It's an OTO kit as well but it's tests for pH, TA and CYA are pretty much as good as Taylor's.

The FAS-DPD test is sold as a stand-alone test by Taylor. I believe it's the K-1515--and using it with the K-2005 for the chlorine test instead of the DPD test makes the K-2005 the same as the K-2006.

Cal-Hypo powder is sold in pool stores, including WalMart (but not the stronger stuff).

There are Leslies stores all over the Atlanta area, but only one inside the beltway.

It's not that I'm a big fan of Leslies--but that they are the ONLY ones that sell exclusively Taylor drop test kits, even when they are badged (and overpriced) as Leslies own. And the quality of their pool chems is usually good, if also overpriced.

Personally, I found a store years ago that sells 12.5% Liquid Chlorine (same as bleach only stronger) in 5 gallon carboys for $20. They cater to pool maint services so their turnover is tremendous and their stuff always tests at 14% or higher. I use that. They are a good drive but I combine errands when I go there--Orthopedist, electronics supply store, Harbor Freight, better Home Depot than my local one, etc.