I put about .75 gallon of the concentrated outdoor bleach in my 20k plaster pool how bad is this?It will eventually dissipate, break down, or get caught in the filter. You shouldn't need to change the water. You can speed things up by scooping out suds if there's really a lot of them. You can still use the pool in spite of the foam. Just be patient and think of your pool as a washing machine, at least for now. :-D :splash: