i have a 38g laying around that i thought i would try sw with. i have 2 penguin 200 filters, heater, and an aquaclear 400gph powerhead. the light is only 17watts but i think fish only is how i wanna start(but i can change the light if needed). i am looking for advise on what/how much sand and/or rock i need. also what protien skimmers are good and any other equipment i need. one major question i have is how to make and change sw, is RO water neccesary? can i use tap water with declor. like my fw tanks? i know that sw takes lots of time/money so i will buy what i need a little bit weekly, what to buy first to last? thanks in advance for any info!