What is the worst rookie mistake youve done?

[gemz]

Oh man..the countless mistakes and money down the drain!
I remember when I first started out with a10gal tank from walmart...
-of course I used sink water! and stupid me I would just pour salt right into the tank! I bought about 5 damsels the first day..all of which died in about a week...
-Oh I cant forget the time I wanted shrimp..they were feeder shrimp (so like 12 for a dollar) i poured them in and they all burrowed in the sand...and I was thinking "this is really cool, I like these"..20min later..all dead! why? turned out to be fresh water shrimp..poor things were suffering trying to get away!
-A mistake I made much later on when I had a 55gal (fowlr) I switched from a regular hang over filter to canister filter...the first time came for me to change out media and wash out filter pads but I did it all with fresh water...Oh the heartache I had the next morning when I went to feed .... my niger and and copperband (which I had for a year or more) and some other fish were floating on top! Washing with freshwater had made the pH plunge way down and the only things that survived was a super human yellow tail blue damsel(hes gone thru so much) and goldstripe maroon clown (which i still have both today)

Gosh I feel so horrible all the mistakes Ive made!...today I am much more patient and make sure to research all I can!

[edshas2]

Have a friend who has a fish only tank and had algea growing on the walls used and old sponge that he though he had washed out good enough to clean walls. few hours later fish where dead or dying and he had soap bubbles in water.

[danny]

It's funny but I don't have any stories.....I'm too paranoid to add anything other than live rock, a few damsels and a couple corals. Perhaps once I feel more comfortable. It's been about a year thus far. lol

[Big_Pun]

Well i learned an important lesson this week never put your frags on live rock till you glue them down. I lost a couple heads of a galaxia that feel on top a Torch face down, also learned to watch my water level closer i have a surface skimmer attachment and it got low, so air mixed in so water got real turbulent and ripped apart part of my torch lost one whole head. pretty sad this morn. Sad i learned a lesson at the expense of my beautiful coral.

[kkralicek]

The stupidist thing I did when first starting was add RO water after water change then add salt after to get the salt up. BAD IDEA!!!