Actually, I was just about to ask a similar question... I had gotten one each of the 250W and 150W double-ended low-cost HQI's from fishneedit on eBay with the 6700K bulbs, originally intending to use on freshwater planted tanks.

I'm now looking at setting up a seahorse marine tank, hopefully with some seagrasses if I can find them anywhere...

The 6700K ok then it sounds like. Good! :-)