Stabilizer Mystery

[TonyPH12345]

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?

[TonyPH12345]

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!!

[PoolDoc]

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

[chem geek]

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

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.

[CarlD]

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

[TonyPH12345]

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...

[madwil]

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!

[TonyPH12345]

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.