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