I'm looking into modding my 14G biocube so that it may be plumbed into my larger, very well established 75G with a 15G sump.... the logic would be a return with a 1200, and additional flow with a 1200. Could be turned off at anytime, and still run fine, but would benefit from the ato on the 75G as well as making 2 water changes into one, as well as only having to test one set of water parameters instead...

Has anyone done this? The other poosibility I thought of is using this as a frag tank for softies etc, benefitting from the cleanliness of my 75..

I do it with a 150 which has a 55 gallon sump, and a 30 and 40 breeder, and a 10 gallon species tank.
I think it makes the whole system more stable, with increased water capacity and certainly simplifies water changes, but keep in mind that it can cause grief to everything if something goes wrong.
For instance, I had a friend who kept a fish only (angler) nano connected to his larger system and ended up polluting the whole system with the waste from feeding the angler. Everything looked great for awhile but finally the whole system got overloaded.
In your case, if you have a tank with sps and you wanted to connect a softies tank, be aware that the softies can produce organic compounds that can inhibit the growth or kill sps. Using carbon on the overflow of your softies tank can help alleviate that.

I don't see why it won't work. From what I've seen, its how LFS do their tanks. My LFS has a dozen 55g+ tanks and several dozen of those smaller display tanks that are all plumbed to the same sump system (or maybe there is more than 1...).

I've seen other LFS do this style as well. It's what I would do if I had a sump and several other tanks.

Been looking into hooking my JBJ NC 24 up to a ten gallon tank as a refugium, im intrested in how you will plumb it if you decide to. I have been thinking of driliing in a stockman stand pipe.

The basic idea is to use the current pump(maxijet 1200) for circulation in the tank, leave the heater in chamber 1, take the fuge out of chamber 2, add 3/4" bulkheads to each of chamber 2 and 3 at the approximate heights shown. Return to the sump would be the bulkhead in chmaber 2, and ingress from the sump would be in chamber 3 with a 90 or 45 degree elbow to point the flow down torwards the mj1200. If the even that I decide later on to seperate the tank, all that would need to be done is to cap off both bulkheads, and the tank would run as normal.

Benefits:

• Dilution is the solution to pollution
• more stable temp with larger amount of water
• use the awesome biodiversity of the 75g w/ sump to help with nutrients in the 14
• could be used as a large lighted refugium w/ seahorses etc later on
• tank still runs as normal if 1200 returning water from sump to 14G fails
• makes use of autotopoff on 75G sump tank, reducing maintenance

Disadvantages:

• 75G tank crashes, 14G tank could crash, unless caught in time
• lessens the possibility of usng fuge in chamber 2 later on, with addition of bulkhead(less area for lighting)

I've gone ahead with this idea, with a modification. My 75 Gallon show tanks Blue Line 20 still has some pressure left over(enough to push water up 2.5' to a biocube through 1/8" waterline), which I will be feeding the calcium reactor, and this tank with. While the transfer of water may be slow(or not), it will keep the water circulating with a larger mass of water, thus utilizing the benefits listed above still.

I did this with my NC 24 I have a 15 gallon sump/refugium. I cut holes in chambers 1 and 3, the hole in chamber 1 is plumbed to a hoffer gurgle buster overflow, and the return is plumbed into chamber 3 and plumbed into the outlet in the false wall of the tank.

Ahh cool, makes sense. I'm trying to keep this versatile... I.e. plump the drain and return seperate from the internal system, in case I decide to split them apart late... just have to cap the bulkheads, and good to go.

Thanks for the input!!

I did the work this weekend, and now have my Biocube 14 Plumbed into my 75 Gallon tank. I ended up using 3/4" threaded Bulkheads and used 1/4" to the tank, and 3/8" to drain from the Biocube back to the sump of the 75. Adding the bulkheads was simple as pie, and now I'll save the time of having to top off, do an extra water change, and benefits from the CA reactor on the 75G as well. I also added a ball valve, so to shut off water in case of a problem on the 75 or the 14, which allows both tanks to run seperate, or together. I'd have taken pictures, but ran out of time, due to forgetting 3/8" tubing while I was at the store earlier in the day and had to run back to get it. The attached picture on an earlier post is almost exact diagram of where the bulkheads are placed, with the exception of the bulkhead in chamber 3 being closer chamber 2, but still at the same level vertically.

How hard was it to drill?

It wasn't bad at all, I used a dremel with a carbide bit, total time cutting the two holes was about 30 minutes, give or take. Since this tank is running, I did the following:

for each chamber:
put filter floss below the spot the the hole in the chamber, and then covered the top of the chamber with filter floss, so that any debris and dust from cutting was contained. I got the filterfloss wet before starting the work, thus trapping the dust, when I was done, I pulled the floss back out, and while doing so, kept it against the sides to mop up any extra particles from drilling. once the two 3/4"+ holes were drilled, I attached the bulkheads facing outwards so that there is still room inside the biocube(bulkheads wont fit the other way. Rubber ring on the inside to seal. Now I didn't setup a durso, because the noise was low when I first set it up, since I'm starting to noticed the noise more, I think I will modify once I get the parts, and add 3/4 threaded 90 elbow inside, and a 3/4 threaded T on the outside, cap the top, drill a hole, reconnect the 3/8" hard line to the bottom of the T. This should reduce the noise quite a bit, but takes up extra room inside the biocube's 2nd chamber. I'll try and get some pics.

Quick update: almost 9 months later, this has run quite well, lowered the temps, and saved me from doing any more topoffs or water changes on a biocube, sitting right next to a 75 gallon tank.

Almost a year later, and I have had absolutely no issues with this setup, other than the circulation pump(MJ900) in the biocube getting clogged with debris coming from the return from the big tank. That should be a pretty simple fix though, usually it's easier to just clear out the pump and turn it right back on..