Stabilizer Mystery

[TonyPH12345]

Ok, folks... I've got a bit of a mystery on my hands, starting with a pool full of clinging green algae.

It's a concrete / plaster pool of about 9000 gallons, with quite a bit of green algae on its surfaces. It's chlorinated with a Rainbow Puck-type automatic feeder.

I've shocked it three times over the past two weeks with about 2 pounds of granulated chlorine each time (plain Cal Hypo, not the Dichlor or Trichlor type)

Very limited improvement seen in the algae.

So, I tested my CYA level and was surprised that it was ZERO. I mean, 30 seconds after adding the reagent, the water was still clear as a bell. And this is brand new reagent bought yesterday.

So yesterday I added one gallon of Instant Conditioner, where the label says that 1 gallon will increase CYA in 10,000 gallons to approx 30ppm.

This morning I tested again, and the CYA is only a trace. It does cloud up, but it's certainly not 30ppm.

What's going on?? What's happening to my stabilizer?? This is the first time in 13 years I've had to add stabilizer! Well, actually I had to add stabilizer once about 6 or 7 years ago when I did a total drain and refill. But you know what I mean.

Usually at the beginning of a season I do a partial water exchange to REMOVE high stabilizer.

I'm puzzled, and I'm afraid maybe something in the water is interfering with the CYA test, and I may be making the situation WORSE. I'm fairly sure that there is, in fact, NO chlorine after 24 hours by using both a DPD and OTO chlorine tests.

[PoolDoc]

I'm out of time -- I've got a Scout weekend I'm working with, and got near a computer, but can't stay -- so very, very briefly:

Your stabilizer has been 'eaten' by bacteria. Read this:
http://www.poolsolutions.com/tips/wh...sappeared.html

Meanwhile, raise your pH with borax to around 7.8 - 8.0 and than start dumping in 2 - 3 gallons of bleach every night. It is going to take a LOT. But, by the time the ammonia is gone, your algae will also be gone too. Expect to spend a week on this.

Do NOT use anything but bleach and borax, right now.

PoolDoc.

[chem geek]

You can read more technical info about this phenomenon in Degradation of Cyanuric Acid (CYA). You can also read about my personal experience with this in It Can Happen to Anyone - Zero Chlorine, CYA --> Ammonia.

[TonyPH12345]

Yesterday after I posted that, I added three gallons of 6% bleach to the pool. That was after I read 0 chlorine with both OTO and DPD.

24 hours later, a Color-match DPD is registering 2.0ppm FC and 3.0ppm TC.
An OTO test was WAY OFF the SCALE yellow. So I think the DPD is being influenced by HIGH chlorine, and in fact I still have chlorine after 24 hours.

The CYA test today is showing < 30ppm (it's cloudy, but the cylinder gets full before the dot completely disappears.)

Other tests:
- pH of 7.6
- TA of 120
- CH of 240

I'll keep testing each morning and see what happens with the chlorine now. I may have been "Crossing the Hump" as I called out for help.

[TonyPH12345]

Today, TC was back down to 1.0 with both DPD and OTO tests... 3 more gallons of bleach in... Pool looks lousy...

[aylad]

If the pool is green, then the chlorine is going to be consumed very, very quickly by the algae. The only way to get that cleared up is to get your chlorine level up to shock level (12-15 ppm) and KEEP IT THERE until the green clears up. If you shock it, then let the level come back down to 1 or 2 ppm, then it's not going to clear. Rather, the more consistent you are about keeping it up in the 12-15 range, the faster it will clear up. You need to add more chlorine to get the levels back up, at least 2-3 times daily, and more frequently if you can. Shocking is not a one-time thing...rather, it's a process that takes some time and sometimes LOTS of bleach. Keep that chlorine level up until the pool clears and until you're not losing more than 1 ppm of chlorine when testing after sundown and again before sunup.

AT this point, the CYA is not that important to getting the pool looking good--I would just concentrate on the chlorine.

BTW, your pump/filter needs to be running 24/7 through this, cleaning your filter as the pressure indicates. THe chlorine will kill the algae, but your filter is what will remove it from the water.........

Janet