Flushing with tap water?

So I recently got my grow up and running,
I got some clones from a dispensary and transplanted them into pot of foxfarms ocean forest, but there were some problems and some started drooping, wilting, and yellowing.
After testing some things out it seems like the soil has a little too much nutrients for the babies to handle, the ph of the soil from the runoff is too high (about 7.2) and also the drinking water Im using has a ph of around 6.7...
I was wondering what the best way to flush the pots with is, I'm using 5 gallon pots and have read that you want to flush the pots with about 3x the amount of water the pot can hold, but I don't know how i can get 15 gallons worth of good water per pot for 12 pots.
Any ideas on how I could go about healthily flushing these guys?
Also, could I add ph down to the water to make it balance the soils ph? Or is that a bad idea.
Thanks for the help

Edit: Also, the tips for the fan leaves at the bottom were getting yellowed on most of the plants, which I thought indicated nute burnage.

Edited by hibred, 11 March 2009 - 07:06 PM.

Depends on your tap water. Assuming it is relatively clean (low PPM) and relatively neutral pH and doesn't burn your nose from chlorine smell, then you can cheat a little. What I do is prepare some pH-adjusted water and let it sit out 24 hours to evaporate out the chlorine, just as usual. I try to get enough water for at least 25% of total volume (so in your case 5gal x 12 x 25% = 15 gallons). Then flush with the tap water, if you have a hose attachment in a bathtub or shower that works great or garden hose outside. After thoroughly flushing this way, I then use the prepared water. This will "push out" the tap water in the soil which will run out the bottom and the water left in the soil will be largely from that prepared water. It's not a great approach, my concern is chlorine from the tap water more than anything else, but it seems to work for me.

Hrm okay, in my area the tap water ph is about 7.8, pretty high but that's a good idea I'll work on it..
So PH Down doesn't hurt the plants that much either? Someone was telling me if I could avoid adding chemicals, to do so...

i use a 35 gallon trash can and let sit for a couple days (at least 1) to let chlorine evaporate, with a small air stone in it.
I just flushed my babies in 5 gallon pots first 5 gallons I added 2 tbsp dolemite lime to stablize the ph then 5 gallon of water then 1 gallon of water and nutes ph balanced 6.5
my pre flush runnoff ph was like 5ish
now its perfect 6.5
I did a couple every day or two untill I was finished with all 10