If your sure sps are not in the future then 6 would be fine. Eight would give you the punch and flexability for other corals. You could always run more bluer bulbs for now. I ran a 6 bulb {not Tek} over my 90 and it was plenty for most all corals, except sps from midway down.
And the are "quiet" because they dont have any active cooling. IMO, I would not run them without some form of cooling fan, even with them having no protective cover shield.
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Doug
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