Hi everyone! I agree with points from everyone's posts. I just started up my 125 gal and though I dont have my final fish in there, I have not yet seen any problems in my first month. I have juvenile goldfish of which I acquired from my naturally spawned pond fish (surprise!) serving as my cyclers right now. I've kept fish for a while and luckily I have acquired that oh so valuable patience before adding fish to a new tank. However, I know this is VERY difficult to obtain, especially with beginners! What I am surprised with so far is that I have not seen any adverse effects on my new set up. From my personal experience, water changes and constant monitoring in those first crucial weeks are the key. The other two important factors I very much agree with is the addition of only a few fish at a time, a few weeks apart, and absolultely the filter having a chance to establish that BB colony. I have recently been gaining experience on dirting tanks (this is my 4th) and everyhting is working quite well. A personal opinion, but I also think live plants are nothing but beneficial. The light demands tend to go down as well if you have a nutrient rich substrate. No need to rock those huge expensive HO fixtures (though I have two myself on the 125 gal, plus a good ol Lowe's T8 ballast). Though helpful later, I also agree the gravel doesn't really play a part in establishing a tank right off the bat. The magic happens in the filter media. I'm not a fan of chemicals or fertilizers, especially those used only for aestetic reasons. If your tank is unsightly, there is an imbalance, plain and simple. Though most won't be interested in becoming an aquarium "chemist", it is beneficial to know the basics. Organic potting soil is super cheap from any gardening/home improvement store if a planted tank is desired. With all of that, I think the easiest and fastest keys are: 1) sufficient filter size for your tank 2) always de-chlorinate, etc. your water 3) Add only a FEW fish at a time- if a mixed species tank, put in the hardiest species first 4) get a master test kit...a small investment to protect your larger ones. NOT the strip tests, get the liquid dropper ones. 5) 20-40% water changes weekly for the first few weeks. Perhaps more if your ammonia/nitrites start to spike 6) don't overfeed- fish dont need 3 meals/day 7) Something like Ammo-Lock is good to have on hand, but being proactive and monitoring your new addition shouldn't require it 8) If tank goes green/cloudy, let it, but keep testing and water changes 9) tank should clear up and filter established after a few months, VOILA! If you desire plants 1) Dirt the tank if you desire heavy plants (1/2 to 3/4" dirt, "capped" with same thickness of any aquarium gravel). 2) Heavily plant, maybe even include floating plants (can remove later if desired) to take up excess nutrients 3) water exchanges almost daily 4) expect some "melting", but not always inevitable (plants eroding away, will come back) These rules have served me well for years and I cant remember of ever suffering from "new tank syndrome". A little research goes a LONG way for this wonderful hobby!