You can flush just fine with plain tap water if you correct the pH.
8 gallons is a very large pot for young plants like that. Generally, a 2-4 month old plant can live happily in a pot between a quart and a gallon. Anything larger, and you will have trouble with soil outside the root zone sitting wet since the plant can't get to it.
That's a CrAzY high pH- fits with the lokout symptoms but double check your meter calibration if you are using a meter.
stinkyattic Reviewed by stinkyattic on . Tried many different things but still have sick babies check out the pics please :(Hey everyone u guys have been giving me kickass advice since i signed up here and im slowly learning enough to be able to help other people out...I have one big problem though that i have no idea how to figure out. After about 3 weeks of 24/7 light growth the tops of a couple plants started going really yellow and shrivelled and the bottom leaves were getting brown spots and going yellow after a few days as well...I found out last week that the ph in my water was 8.5!!. so i adjusted it to Rating: 5