I have had this BC29 going for about a year. I always thought it to be kinda loud with the bio balls removed and a skimmer in the second chamber. I made the overflow part between chamber 1 and 2 wider all so. My question is once I go toppless with my new NEP 20" light that I'm getting this week, how can I make it queiter with no top on to muffle the waterfall sound?

can't really do anything besides raise the water level. anything else will possibly cause flow restrictions.

+1 for raising the water level, the noise annoyed me also. When i scrapped the bioballs i filled it to about 1/2" from the top of the tank. Thats keeps my 2nd chamber level higher enough so there is no waterfall, which causes the annoying noise.

Here is what I did. Made this holder and put filter pads and polyester fiberfil on it.No more waterfall noise.

I just raised the water level as well. or you can put some polyfiber in the second chamber and it mutes it a lot or takes the excess noise away completely depending on how much you add.

Raised the water level but like the idea of the try and filter pad. Will try something like this also. Anyone that has gone topless how much more due you have to top off compared to the top on?

My tank takes about 2 gallons a week. I have a Reef Fanatic ATO with the floats in the 3rd chamber. An Aqualifter pump and a 5 gallon plastic water jug.

I am topless on my biocube 29. Get a media basket from www.mediabaskets.com that will cutthe noise down.Also raise the water level. I have a Sunpod HQI on mine and my topoff went from about 1 gallon a week with the top on to about 4-5 gallons a week.