Brown tips working their way up, nute problem?

So, I'm just over a month into my grow. A bit over a week ago I transplanted into a big 5 gallon container, poked holes in the bottom of it, and them fimmed (I think somehow I fimmed the fimming, hah) the plant. After that it went through a little shock and I wondered if maybe it needed to be flushed (approx 25-35% of the soil mixture is MG Potting Mix) so I ran something like 5-10 gallons of water through it, and it recovered. Then I noticed the very tips of the leaves looked a bit burnt, and I went on vacation for a few days, letting automated stuff be automated. By the time I got back I saw the browning tips had gotten a lot worse. Its the worst on the lower leaves, and is steadily working its way up. The tips are still soft, not dry at all. I attempted to break them off but they were just as soft as the rest of the leaf and in no mood to seperate.

Soil mixture:
50% Scotts organic topsoil
25% Perlite
25% MG Potting Mix

No nutes have been applied at all besides the stuff in the MG Potting Mix. I don't have any PH testers or anything fancy at this point. I was hoping someone could tell me whats up without having to buy one of them.

Pics:

I'm no pro or anything, but I know that salts tend to collect at the tips of fan leaves and eventually burn them. You may want to flush your soil. I usually just cut off the dead part with sterile clippers.

Try adding Drip Clean to your regimen. It helps prevent harmful salts and other build ups from occuring in your medium.