aciam - Nightmare conversion from baquacil to chlorine

[reesie]

Hi aciam,
It's reesie. Yes, I used CDX the last 1 or 2 years ( I think 2 years) and the tablets the year before just like you. I didn't realize it was going to come back to haunt me!

[chem geek]

FYI. This patent talks about using various aldehyde donors (as Evan mentioned) including DMH equilibrium compounds in water to stabilize hydrogen peroxide though that stabilization is described as preventing too much reaction from decomposing enyzmes often found in some organic matter (such as recycled paper). They don't mention stabilization with respect to sunlight. Anyway, I'm going to see if most of the conversions at TFP that went well didn't use CDX. The same should be checked here as well if possible.

[aciam]

Hi Chem geek - so the sodium percarbonate has arrived - we had a medical emergency in the family so I have had to put the pool stuff on the back burner - I am hoping to try the bucket test sometime in the next few days using 1/8th tsp of Na percarbonate in 2 gallons per your instructions but just need guidance as to what I am looking for and how long to wait before I retest the bucket water. And how I will know it has worked - or if I need to repeat the dose and retest in a certain time frame. Thanks. aciam

[waterbear]

I would do it like this:
sprinkle it on the surface of the water and let it sit for 48 hours, stirring every so often. Then add 1/4 teaspoon 6% bleach (this should raise the FC by approx 20 ppm), stir, and test with OTO, it should be dark yellow orange to brown if the chloirne is holding (percarbonate destroys chlorine and vice versa but after 48 hours I would think it was all used up) . IF it is still very pale yellow or clear add another 1/4 teaspoon bleach. When the bucket is holding chlorine. test with FAS-DPD and see if the CC problem has been solved (HIgh FC, little or not CC). Let it sit an hour or two and test again to make sure CC has not climbed like it has been.

If your test results are better than before the percarbonate it is probably worth a try. Like I said before it might take two or three applications. so If the first time is a no go repeat the percarbonate on the same bucket of water and see if two ( or even three applications) do the trick (wait for the chlorine to drop low first...a few hours of sunlight should do it). If so just add your dose to the pool every 48 hours with pump off, skim, and fitler for 48 hours then shock with chloirne and test.

Chen geek might have another way to do this.

[chem geek]

I think what waterbear described is a good approach.

[aciam]

Hi guys - so I read Reesie's thread and was excited about her positive results. I started my bucket test at 3pm yesterday 6/21 and decided to follow her protocol. The water tested at FC=4 CC=20 ( I had put in 2 gallons of shock over the day trying to get my FC up but as you can see all it did was raise my CC) prior to adding 1/8 tsp of sodium percarbonate

6/21 : 8 hours later I tested the bucket ( 11pm) FC=0 CC= 6 repeat test 8
6/22: this morning 830 am (17 1/2hours in bucket) FC=0 CC 6
930 pm ( 30 1/2 hours in bucket) FC=0 CC 8

of note: I forgot to rinse the vial after this mornings test and when I arrived home from work the liquid had turned a deep purple
Also, I am finding that the water is only turning a light pink once the second reagent is added ( for the CC) but is very very resistant to being titrated to clear - and upon sitting after the test is done, starts to turn pink again.
Any ideas as to what this means?

Since I feel like I have hit a wall, I decided to add another 1/8 tsp of the percarbonate to my bucket to see if it will oxidize out the CC for I feel like I can't go further with this experiment and add bleach if I can't even get the CC to go away. Was that OK? any other advice? aciam

[chem geek]

Yes, I think it's OK for you to hit with more sodium percarbonate to see if that lowers the CC further. At least going from 20 to 8 was a good positive step and you did the right thing not to add the bleach yet since you were still measuring CC. Your situation may be more extreme than Reesie's. Keep us posted.