I was given some plants last night and was wondering if its cool to just let them float in a tank for a week.Do they need to be planted upright?I have them in a 10gal with a little AC filter and a heater with a LED singlebright light over them.I did put 1 cap full of Flourish excel by seachem in the tank.Is this alright?Should I weigh them down so there not on the surface?