Stabilizer Mystery

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.

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.

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.

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.

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

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

"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."

If you are describing these results accurately, you were measuring a pool with low FC and high CC. And, yes, high CC seems (sometimes) to show up as FC.

I've never known CYA to be metabolized that rapidly, but then I have no really info on just how fast it can be metabolized. But, it sounds like you've got an algae/bacterial soup that's eating your stabilizer (and turning it into ammonia) as fast as you can add it. My original recommendation (borax to 7.8 & 3 gallons of bleach each and every PM) was almost certainly the right thing for you to do. It certainly would help you resolve your green goo.

It doesn't sound like you've done that consistently.

Messing around with the CYA, TA, & CH now is more of a distraction, than an aid. You need to get the goo (and probably, the ammonia pooped out by the CYA eating bacteria) dealt with first, BEFORE you worry with the other stuff.

If you want to really understand, read Chem_Geek's articles. Otherwise, just do it.

Ben

Ben, I've given up on the DPD test. I'm measuring whatever the OTO test measures... Isn't that TOTAL chlorine? Ordered me a replacement K2006 since my previous one is "expired" and I'm out of FAS-DPD powder anyway.

At any rate, this AM I'm seeing OTO test off the scale again (water is almost brownish yellow after adding 5 drops).

Through this whole time, my attached SPA has not had a trace of algae in it. It was crystal clear and snow white as I wish my pool were... Odd, huh? But now it is developing what looks like metal stains...brownish orange deposits on the plaster... I've had that happen before and know how to deal with that, but I'm not going to touch that until this is resolved.

The "Algae" deposits are turning grey, and they're becoming easier to brush away. But what's under the brushed spots is not clean plaster... It's still green underneath. Other than adding this turbidity through brushing, the water is clear. So all the algae is clinging algae, not water-borne.

So right now I don't have a reliable way of measuring FC. In the mean time, if my math is right and I can assume the bleach is actually 6%, adding 3 gallons of bleach to 9000 gallons of water should raise FC by 20ppm, is that right?

Thanks, ya'll, for the hand-holding. We're only about 3 to 4 weeks away from Swim Season here in Dallas, and I'm sure hoping I don't disappoint my kids.

If you've got 3 weeks, and your filter is functioning reasonably well, you should be fine.

Grey is dead; green is live. (tho, I think you'd worked that one out ;-)

RAISE THE PH!

Adding chlorine to ammonia in a HIGH ph solution produces monochloramine, which is GOOD at penetrating clinging algae. Free chlorine is not. Monochlor is what Yellow OUT leads to, IF you follow the directions. It does work; it just leaves a mess to clean up. But you've ALREADY got the mess, so no worries there.

But, if you don't raise the pH, you'll tend to produce di- and tri- chloramines which are stinkier and are NOT good for anything that I'm aware of.

20 ppm is about right. If you brush and stuff, it will drop very quickly. But, you should probably stay out of the "brown" OTO range. I think 20 is dark dark orange.

Ben

I think I see something: Your CYA didn't rise because it takes 48 hours to a week for the CYA to dissolve properly...and if you've been vacuuming to waste you may WELL have vacuumed up and out the undissolved CYA particles.

You've got a gunite pool. If it were me, I'd get a 5 gallon carboy of 12.5% liquid chlorine and dump in 2.5 gallons. That should raise the FC by about 30ppm, which may just make a dent in the algae. 8 hours later, I'd check FC again, and if it dropped, I'd dump in the rest of the LC. Gunite/concrete/plaster can tolerate such high levels, unlike vinyl.

When you use the OTO, are you diluting it with steam distilled water? If not, look up the Shot Glass method. Mix one shot of pool water with one shot of distilled, and you can double the readings. Two shots of distilled to one shot of pool water and you can triple the reading. 3 shots distilled, quadruple. Beyond that you will probably be losing accuracy.

Yeah, I didn't mention that. I'm titrating the pH up to 8.0; I've never used Borax as pH increaser before; only used Soda Ash before. So I don't know what the dosing should be and I don't want to over-shoot it...

Does high chlorine affect Phenol Red test? IOW, can I trust what I'm seeing on the Ph test when my chlorine > 15?

CarlD: Walmart is less than 300 yards away from my front door. 1.5 Gallon bottles of 6% bleach at $2.00 per bottle is a lot more convenient than to find a 5 gallon carboy of 12.5% :)

My filter doesn't have a setting for Vac-to-Drain; it still recirculates. So I don't think that's where my CYA went...

Thanks for the suggestion!!

Tony, you're right to remember that high chlorine affects phenol red . . . and in spite of having warned about that many times, I was forgetting it. But I lucked out, and still gave good advice. High chlorine makes pH appear high, not low. If you are still reading low, (7.6) I think it's prudent to assume you are.

In any case, the higher the pH, the greater the propensity to form monochloramine preferentially over other species. (So, add borax!)

Ben

Quote:

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Originally Posted by PoolDoc

In any case, the higher the pH, the greater the propensity to form monochloramine preferentially over other species. (So, add borax!)

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Just FYI: monochloramine forms almost immediately (in less than a minute in pools with recommended FC/CYA amounts) when chlorine combines with ammonia and this happens at all pH levels. Higher pH levels tend to produce more trihalomethanes (e.g. chloroform) when chlorine oxidizes some organics (those that have or end up with methyl ketone groups) while lower pH levels tend to produce more nitrogen trichloride from multiple substitution with ammonia and partial oxidation of urea (i.e. it is a disinfection by-product). Generally speaking, at the low active chlorine levels in pools with CYA and the low bather-loads in residential pools, I wouldn't worry about either.

Tony, If WalMart is 300 yards away and 1.5 gallons are $2, go with it. It doesn't matter if you use Walmart 6% or carboys at 12.5%, as long as you get your FC where it belongs and keep it there. I like the carboys because I can get them easily, easier than bleach and the price is generally good. Plus the jugs are reusable like deposit bottles. But the important thing is you are using sodium hypochlorite. In that, there's no difference between bleach and Liquid Chlorine.

As for CYA, it still takes 2-7 days for it to dissolve and affect the reading, so you cannot expect immediate results.

CarlD

Heheh... With as much NaClO as I've dumped into the pool in the last five days (I'm up to about 12 gallons so far) I will probably end up with a significantly salt-water pool!

But things ARE improving. The algae deposits continue to oxidize and turn brown and brush away. I've removed the Polaris' bag because it's not doing much good other than to clog itself up with slime, but the tail sweep is helping somewhat, and it's agitating the junk on the bottom back into suspension in the water to draw into the filter...

Pressing on...

12 gallons? I used about 50 last year, after my 2 week vacation without any Cl added to the pool...
Keep adding, keep the FC at or above the right levels per "best guess" chart, and the algae will clear!

Ok, so for those keeping score, here's the final...

I put in a total of about:
30 gallons of bleach (20 1.5 gallon bottles)
8 pounds of CalHypo powder (to "Spot Treat" some areas in the fillets of the steps and lounge)
5 pounds of Borax
25 pounds of DE
I also:
Replaced two DE grids
Replaced my original Rainbow 320 chlorinator with a brand new one

...before things finally went "static."

Once things balanced, I also found need to raise CYA again (which I did with three pounds of Dichlor shock)
Floc'd and Vac'd.
Backwashed a total of three times.
Opened and Cleaned the filter after the final backwash. The smell was indescribable!

For the last two weeks, my pool has been around this mark:

FC 3.5 to 5ppm
CC (none)
CYA 30-50 ppm
TA 120
CH 320

... but I think the pool ultimately won the war. I think I'm going to have to replaster. But that's a subject for another thread.

Thank you ALL for your help! I couldn't have gotten past it without ya'll.