Ok you guys are correct. I went to dealers electric today and he said the thing about overdriving and blowing the bulbs. I really only needed to know because I want to get a mh
for a 20 gallon, but want it to be big enough so I could move it to the bigger tank later if I get tired of the 20. 175w is really overkill for a 20 gallon but it's a little harder to find a 70w or 100w system online. I'll probably just go for the pc
's. They could at least be converted to freshwater if I wanted to later on.