My dad wont let me get a bigger than a 55g because itll be in my room along with my 150g and hes worried about weight which I understand. And its fine I really like them but this may be put on the back burner> i dont no if you have to use RODI water or can I use water from tap and use the conditioners in it like I do with my freshwater tanKS/
Tap water is fine if you use a saltwater conditioner although RO/DI is better; the main thing is that you'll have to be a little more diligent on your water changes if you use the tap water. If you're not going for a reef, then tap water should be perfectly fine for your purposes since you have a little more leeway on the water parameters.