All bleach contains sodium hydroxide. It is necessary to keep the chlorine gas in solution and part of the maufacturing process. However, the Clorox outdoor cleaner seems to have a range of chlorine concentration while their other bleaches are more exact. I would use caution about putting it in the pool. I noticed it at the Home Depot near where I live and it was actually more expensive than the regular Cloriox bleach. The only bleach that Chlorox documents on their website for pool use is the Clorox Professional Commercial Solutions Ultra Clorox Germicidal Bleach. I guess this is just plain bleach without their new whitening additive. You can probably get this stuff at a janitorial supply house but I have no idea what the price is.