Coated magnets for frag shelf

[seminolecpa]

Levi,

Did you have any luck with this? I really want a place to put frags in my tank as the plain bottom doesn't work with all of my flow. Think this could be a good solution.

 

[Mr. Ugly]

I have round magnets for a frag mount project that I have yet to do.

I'm just gonna stick the magnets inside some plastic bottle caps and pour some 2-part casting epoxy inside the caps. Got the epoxy at TAP Plastics a long time ago.

 

[fishnfst]

There was a link somewhere to someone who made diy seio holders.. I'm pretty sure he used the casting epoxy that Norman is talking about.. He went as far as drilling and tapping the epoxy to mount the powerheads to them.. Maybe if you made your own you could incorporate a coral cradle of some kind into the cast..

 

[sfsuphysics]

Funny thing today I actually was doing an experiment to see how the forced varied with distance from a magnet, I used a single button battery sized niobium magnet (about half a cm in height), and while it was really strong near it, the force dropped off really rapidly, exponential like! Now these were not the strongest things out there (even though they were a b**ch to take apart) but how quickly the force dropped off was really out there, exponential like!

 

[Gomer]

I'd need to bust out my E&M to be sure, but I think the magnetic field drops off as 1/r^2, (for a point source magnet) just like a metal halide drops off.

 

[sfsuphysics]

a magnetic monopole drops off as that, however they don't exist in nature I was just as surprised though to use excel to fit an exponential series and got an R² of 0.9988, I'll definitely want to try with different magnets now just to see how it works, to see if its a function of the magnets diameter as well as it's width, there's also deals with how the magnetic field splits out, etc.

 

[Gomer]

oops. far field magnetic dipoles are 1/R^3

 

[Mr. Ugly]

Cracks me up what a techie geeky bunch we are

 

[sfsuphysics]

Yeah the field itself goes as 1/R^3 BUT the field also splits so it's not as strong in that sense. I tried a power fit, and I got Ax^-6.2 or something, and that had an fit of 0.9888 which is still really good considering. But I don't know why to the sixth power instead, it's really confusing almost like it was R^3 then ² on top of that. Of course my method of taking data wasn't ultra-precise it wasn't half bad.

 

[LeviT]

Well to answer Bryan's question, YES! I got it to work. I cracked the acrylic when I was drilling it so I ended up with a small cradle so I packed more plugs in it. I ended up with 7 plugs. I didn't know if the 2 part epoxy I had was reef safe so I made the holes for the magnets really tight and super glue them then used the 7/8 thin magnets for the outside since they won't be in contact with water.

 

[sfsuphysics]

Hmm ok could be the field drops as 1/r^3 but the force goes as the field squared (but it's been ages since I've done any of this stuff at this level, so I'm really grasping at straws), but it makes my x^-6.2 seems plausable just a little sloppy on the measurment... ok that's enough geeking out

 

[Gomer]

now you need to solve for the exact force fields for the geometry of your magnet!

 

[sfsuphysics]

uh... no I don't

My experiment ran them with the distance away was sufficiently large compared to the thickness of the magnet

 

[Gomer]

thickness yes, but the pole wasn't a point source!

 

[Qwiv]

Just FYI for you guys
http://www.mag-racks.com/sizesdimensions.htm
I like these racks better. I made a few just like it. Tap plastics sells a resin that will do the job.

The really easy thing you guys can do is use the solid epoxy sticks. Put the magnet inside, form'er up, let is cure.

 

[LeviT]

[quote author=Qwiv link=topic=2854.msg37481#msg37481 date=1205391103]
Just FYI for you guys
http://www.mag-racks.com/sizesdimensions.htm
I like these racks better. I made a few just like it. Tap plastics sells a resin that will do the job.

The really easy thing you guys can do is use the solid epoxy sticks. Put the magnet inside, form'er up, let is cure. [/quote]
Yeah those racks are nice. Someone else in the club bought one, I forget who but he liked it too. I'd trust the resin before I'd trust the epoxy sticks since you can tell if the resin is water tight. His crate is styrene though, we haven't had any luck finding acrylic eggcrate in black so we can make our own.

 

[Qwiv]

Has anyone ever done a side by side with styrene and acrylic racks next to each other to see if one really is better?
I know the potential with styrene from the factory worker, brain damage, killing babies side, but issues in a reef tank?
I'd like to read up on the source of this styrene algae magnet talk we speak.

I can see styrene allowing turf algae to take hold due to its porosity compared to acrylic.

 

[Gomer]

My frag tank is still algae free on the egg crate.

 

[sfsuphysics]

[quote author=Qwiv link=topic=2854.msg37498#msg37498 date=1205432035]
Has anyone ever done a side by side with styrene and acrylic racks next to each other to see if one really is better?
I know the potential with styrene from the factory worker, brain damage, killing babies side, but issues in a reef tank?

[/quote]
damn, so making a baby's bed out of it is a no-no? shoot, back to the drawing board.

On a serious note, Eileen swore that it was the egg-crate/PVC combo which gave her uber algae, so might want to ask her on the subject.

 

[Raddogz]

The hair algae grew only on the styrene along with the valonia and the frag plugs that were sitting on it. - this go around

I've since ditched the egg crate again, and placed the frags on the sand bed.