OK jaw thanks for all the help, gave you some rep++. Heres an update, the plants are looking better. They are all showing new green growth and are standing up tall. So that is definitely good. However, I'm not sure that the yellowing and browing/burning is over. It seems like it is still getting higher. Could this be still due to the ph adjusting? I mean a nutrient burn wouldn't keep doing this, especially after I diluted it with a flush right?
Hmm....It sounds like the flush was successful, but maybe only partially. I should also add that if you left them dry to the point of drooping, that you'll lose a bunch of fan leaves, a few days afre it's been watered again. If that's the case, you can't stop that.
What is the PPH of your tap water? If it's less than 150, you can use it straight out of the tap. I'm lucky, in that mine is only 40 PPM. I use it without letting it sit overnight, or sit at all, and never had a problem with it. Honestly, I don't think letting water sit, actually does a whole lot. I'm sure it helps, but only a small amount, almost negligible.(spelling?) You'd be much better off going with a thoruogh flush, than quitting early because you've ran out of water to use.
For a pot that size, if you take care to make sure the flush soaks nice and evenly, you'd only need about 20-25 gallons for a good flush, not 40 gallons. The best way to 'know' when you're finished, is to monitor runoff, til it's close to the water that you're pouring in. Why pour in an extra 10+ gallons, if you don't have to, right?
At any rate, it sounds like the flush helped, which is good. You could spread a thin layer of lime on top of the soil, each time you feed or water, and that'll help too, if you don't have the time or ambition to flush again, for a few weeks. It's almost impossible to use too much lime, one the plants are that size. Little one's can get PH burn, but the big ones are pretty resisitant against it.