Looking for ideas on securing an in-tank partition

[vol_reefer]

Hi all,

I'm setting up a 2x4x1' frag grow-out tank, and I'm going to try this idea I've seen for flow called a "gyre tank." The idea is you put some kind of wall down the center of the tank (parallel to the long axis, standing upright) with gaps on each end. This creates a "racetrack" kind of arrangement for the water to move around. You set up a couple powerheads facing opposite directions and alternate them to drive the racetrack flow clockwise, then counterclockwise, etc. It seems like it could provide good alternating flow to the whole tanke with a couple cheap powerheads. Not the ideal solution for a display tank, but that's not what I'm building.

I had Glass Cages in Nashville build the tank, and they also cut me a piece of glass for the partition wall in the center, but they were unwilling to mount it in the tank for me. I guess it was unusual enough of a setup that they didn't want to be responsible for the warranty with it in there. So now I have to figure out a way to secure this partition down the middle of my tank without much to support it. I think it's tall enough that it will just touch the underside of my center brace on the top side of the tank, so it'll be in contact with the tank's structure there and also all along the bottom of the tank.

I don't think silicone glue alone would provide enough lateral support for the partition wall. I would prefer to avoid any kind of support that sticks out into the flow (for example, a brace from the sides of the tank) because that sorta defeats the purpose by interfering with the flow. I was thinking if I could find some kind of T-shaped plastic channel, where the glass wall would fit into the leg of the T, that would be ideal - I could glue down the channel pieces to the bottom and to the center brace with the parition mounted in the channels. But I have no idea where I'd find a piece of plastic like that. It'd kind of be like the plastic channels they use to join up multi-segment glass lids on some tanks, except that instead of two channels, one side would be the perpedicular top of the T.

Anybody know where I could find something like this, or have any other creative ideas?

Thanks,
Jeff (vol_reefer)

 

[fishdoc11]

You could just mke the t channel out of 2 pieces of plexiglass glued together and then use silicone to secure the glass partition to the bottom and to the plexiglass.

Here is an old thread fom another (more complicated) raceway design:
http://archive.reefcentral.com/forums/showthread.php?t=281480&highlight=JBNY+frag+tank

 

[Wildman]

I know your center piece is already cut so this might be out of the question. Why not use the center piece as a false bottom? Support it with cut pieces of PVC and run your flow over and under. If you kept it bare bottom would this not be the same amount of flow? You would also be able to access the entire tank easier.

 

[cee]

Silicone alone should be fine. There will be no force on the divider to speak of.

 

[vol_reefer]

Thanks for the replies guys:

Fishdoc: I looked at the thread you cited, and while it's a neat design, it's more complicated than I want to get into (or this will never get done!), and I'm also not sure about the unidirectional flow idea. The nice thing about the gyre idea is that it's easy to reverse the flow around the center partition at whatever frequency you want.

Wildman: Good idea about making the partition horizotnal, but there's a couple things going against that in my particular situation. One is, as you pointed out, I already have the glass for the partition cut, and it is dimensioned to be vertical. The other is that my frag tank is shallow - only 12" deep - compared to the front-back distance of 24". With those dimensions, a horiztonal partition would make for a 24"x6" cross section perpendicular to the flow, whereas a vertical partition makes for a more equant 12x12" cross section perpendicular to the flow. I would think the later type of cross section would put less drag on the flow.

cee - after I posted, I dry-fitted the glass partition in the tank, and it's actually about 1/4" shorter than the height it would need to be to make contact with the underside of the top center brace. So there would only be the bottom to silicone it to, which I don't think would be enough support (particularly if I need to drain the tank).

After futzing around a little, I came up with an idea to use some PVC pipe (probably 3/4") and a dremmel. The tank has bracing (in addition to the center brace) running all around the perimeter of the top of the tank. So I'll cut a couple pieces of PVC a to be a bit longer than the front-to-back opening in the top, and I'll put notches in the ends of the pipes so that they will slide onto the braces on the front and back perimeter - that should keep them pretty well in place. Then, I'll make one more notch on the underside of each pipe for the center partition to slide into, perpendicular to the pipes. The bottom of the partition will just rest on the tank bottom. As cee said, there won't be a lot of force on the partition, so I think this simple approach should hold it well enough, and it will make it easy to remove the partition for cleaning if I want to. The tank is on a set of shelves against a wall, so if a lot of coraline built up on the partition, it would be hard to see the back half of the racecourse, and I think the partition would be a real pain to keep clean in-place.

If this doesn't seem to make the partition stable enough, I'll try Chris's idea of making some channel guides out of plexiglass. I don't have any experience working with plexiglass (in particular, making the butt-end cut straight enough that it would rest flush on the glass), but projects like this are how you learn things like that, I guess.

Thanks again everyone.

Jeff (vol_reefer)

 

[fishdoc11]

I just threw the thread out there for ideas

The only way to make the cut that straight is with a table saw(or with another saw and a very straight guide). So if your first option doesn't work you can get whoever you buy the plexiglass from to cut it for you.

Good luck!

Chris