Hey maggot, i think first thing you should do is check the basics. You've not mentioned what your temps are, have you got a thermometer? Also you mention you've got a fan setup for air circulation but don't say anything about a fan to exhaust the heat out to the grow area, that's something you really need or your temps will be too hot with a 400w in there i'd think, also the plants need a fresh supply of air not the same old air circulated.

Can you post some pics? It doesn't sound right, your plants a month old and only two and a half inches tall??? It should be much bigger than that. What type of light have you got on it? You say 400 watt, but is it a metal halide (mh) or high pressure sodium (hps)?

You shouldn't be watering 3 times a day in soil, in the very early days you might water seedlings in tiny pots a couple of times a day but you pretty soon move onto watering every 2-4 days. I'd stick to watering with tap water, it should have a ph of around 7 and your soil should have a lower ph to buffer the ph down a little. There's a good thread around about ph, have a look for it, i think it's called something like "how and why to test your runoff ph" it's by stinky attic. But first i'd check the basics before worrying about feeding and PH.

Good luck!