Originally Posted by OMGemily
hmmm i think maybe 4 or 5 days. i didnt notice it until i took the gravel out when i changed the water after my last fish passed away, and i keep the light on all the time
EDIT: also i didnt clean the tank before i filled it up... should i empty it and do that?
Most likely it's dirt that you didn't see.. tanks tend to collect a lot of dust when sitting empty. Since you haven't turned the filter on, I would do that now before you start the cycle process.
BUT reading back on it, it looks as if it was going prior and you removed the gravel. If that is the case, then it's probably debris and waste particles left by the other fish/gravel.. I would clean it out still, especially if you want to go bare bottom.
Keeping the light on all the time can be bad for a few different reasons- you will grow algae.. sometimes some algae is good to have, but there are some pesky ones you don't want, such as the brown algae.. and the more the light is on, the greater the chances of growing it.
Also, fish need a day/night cycle just like us.. they need time to rest to recharge their bodies.. otherwise it's a lot of stress for the fish, and in the end, the overall health will be deminished and therefor their life span shortened. Like all animals, they need time to "sleep".