plah831 said:
Seasalt, do you mean 29 gal? Eclipse doesn't make a hood bigger than 29 gal.
A 39 gal has the same "footprint" as a 29 gal, its just taller, so the same Eclipse hood will fit on both. I know, because I have one and, sadly, an Eclipse hood. I believe that a "39 gal" is actually more like 37 gal, based on my rough calculations.
In response to the original question, I was in much the same situation just over a year ago. I had been doing FW for years, had an empty 37g w/Eclipse and wanted to try my hand at SW.
I know I'm going to get some nasty feedback on this but, since it was all I had, I used the Eclipse system and an undergravel system w/ powerheads and (are you ready for this??) NO live rock and no skimmer. With careful maintenance and testing and a very light bioload, I was relatively successful at maintaining the tank with a damsel, bicolor blenny, and a Lubbock's wrasse, a few hermits and snails, a couple of brittle stars, and zoanthids actually grew when I finally added some live rock, replaced the bulbs with a daylight bulb and an actinic, and started a modest dosing regimen of calcium, iodine, and strontium.
To make a short story long, the reason that I set up this tank was to learn about SW using the equipment that I already had, while I planned a larger SW reef setup and was quite successful in my learning.
I still have this setup with the undergravel system in place (GASP!!). And everything is healthy and happy. I am, however, in the process of moving everything into my new 65g reef tank w/sump, skimmer, MH's, etc.
I believe that I will be just that much more successful with my new tank for my one year "practice tank" using the junk equipment that I had laying around, so my opinion is to go for it, but to know that you will be very limited in what can be kept with that setup. It will be a great learning tool and very soon you will be planning your own large reef tank. Good luck.
Sorry for this rediculously long post.