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					Originally Posted by  jassz
					 
				 
				Do the rock need the heater and hte circulation?  Heat shouldn't be a problem, it's hot here.  Would it be all right if I just changed the water every couple days?  I'm figuring this to be a four day event or so...? Do the rocks need any nourishment?  Selco? 
			
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 The circulation is a must.  Your rocks cannot move the water through themselves and if the water just stagnant the rocks will die.  A power head of any size is better than nothing.  The heater is more to keep temp fluctuations to a minimum and although air temperature is warm I'm sure it drops at night.