The mj1200 is rated at 295gph and when placed under my center brace (75 gal too) pointed at the front glass it was making "dunes" in my tank from moving my pfs. I didn't want it on one end so I went with the spray bar choice. What few co2 bubbles make it up and out before dissolving make it about halfway across the top before sinking into the spray bar flow on the front glass from the c530 I'm running on it atm. If I went side to side with just the mj1200 it would probably be about right for what I like but I don't like the bulk of it hanging from the side in the open lol.
If it is gas build up you're worried about get Malaysian trumpet snails. They burrow through the sub releasing any pockets they run into. When I first started I went what I would now consider to be to thick of a sub with dirt (4 or 5 inches roughly) and the mts I think helped with my "mistakes" back then and I now keep them in every tank I set or reset up, even my yellow tail acei tank with its shallow sub. The hard stuff (egg crate light diffuser, rocks, acrylic border etc.) is only going to help shape the features you're after.
To give you an idea on how thick, I put a full .75cuft bag of topsoil in here (55 gal) and used the gravel/ sand the tank came with when I bought it off craigslist as the cap. I didn't see many bubbles back then even with hundreds of mts in the tank but occasionally they did hit a pocket. It was kind of cool to wake up to them all over the glass when the tank was dark and disappear not long after lights on.
ps: you're welcome for the reply
