neodymium magnets

[returnofsid]

Hi all,
I'm planning some DIY projects using neodymium, or rare earth, magnets. I'm just wondering if anyone knows if these are "reef safe" without being coated. If needed, what's the best way to coat them? 2 part epoxy? Silicone? My projects will consist of frag racks, however, I'm also curious as to how these magnets would effect powerheads? Any information as to how large of magnets I'd need? I see them on ebay in several sizes. I'm thinking of using the disc shaped ones that are anywhere from 3/4" - 1 1/2". I'm mainly concerned about how thick they'd need to be. Last question, where would be my best bet as a source for these magnets? As I said, I see them on ebay, but also wonder about local hobby shops. Thanks!!

 

[mfinn]

I put some neodymium magnets in saltwater for about 3 months to see if they corroded or rusted.
I didn't see anything on the magnet except a slight discoloration and I didn't test the water or use any fish or corals in the water.
I was thinking about using them unprotected in my tanks as powerhead holders, but several people talked me out of it. So I came up with a way to encase them in acrylic.
Since then I've found some neodymium magnets that are coated with epoxy.
I've also made some frag racks, using ceramic magnets for the inside that's glued to the eggcrete and uncoated neodymium magnets for the outside.
I found most of the magnets at www.magnet4less.com and www.magnet4sale.com


http://www.gaussboys.com/magnets/blocks/
http://www.kjmagnetics.com/categories.asp

 

[mfinn]

The ceramic magnets I used, I found at a local hardware shop and online have a plastic cover over them made it easy to glue to the eggcrete using just a two part epoxy.

I also made a maxi-mod powerhead magnet holder using a single neodymium magnet encased in acrylic and glued directly on the maxi-jet.
It seemed to work fine. Didn't seem to affect the powerheads magnets.

 

[returnofsid]

How large of neodymium magnets did you use for the frag rack? Also size used for maxijet?

 

[mfinn]

On the frag racks I used a 2"x1"x1/2" ceramic magnets for the inside and 3/4"x3/8" disk neodymium magnets on the outside. This was with 3/8" thick glass.
The maxi-mod holder I made used 2 - 1"x3/8" thick neodymium magnets. 1 inside, 1 outside.
This also was for 3/8" thick glass.

 

[mfinn]

I should have said on the frag racks I made, which are approx. 9"x4", I used two ceramic magnets on the inside and two neodymium magnets on the outside.

I have found that the ceramic magnets I used are strong enough to hold max-jets when used in place of suction cups, though 3/8" thick glass.

 

[returnofsid]

Thanks for the help!! I've been looking at these for the frag racks.
http://www.kjmagnetics.com/proddetail.asp?prod=D82B-N52

I'd use 2 outside and 2 inside per rack.

 

[mfinn]

Not sure if the black nickel coating would be good in saltwater.
Hopefully someone with the right know how will check it out.

I also wonder if painting the neodymium magnet will work?

I'll have to try spray painting a couple I have and see if paint sticks.

 

[returnofsid]

Ooops, linked the wrong one...lol. Here's the one I meant....it's epoxy coated. 1/2" X 1/8" Think that'd be strong enough?

http://www.kjmagnetics.com/proddetail.asp?prod=D82E

 

[mfinn]

How thick is the glass?

 

[returnofsid]

ya know, I'm not sure...lol. It's a standard 75 gallon. Guess I'll have to measure it.

 

[mfinn]

http://www.gaussboys.com/ndfeb-magnets/D1803E.html


To me it was just a guess as to which magnets I've used in the past.

 

[luke33]

I used the 60-80lbs on my 125g and 75g. The 80lbs are waaay plenty for 1/2" glass. The 60 lbs are plenty for a 1/2" glass. I'd use around a 40lb on the 75g. FWIW though, the black rubbed off and some rust happened. No harm to the tank that i've noticed as it was just a bit of rust. You may want to dip them in some epoxy from a hardware store to get them thicker.

 

[Barbie]

I'll go in on an order for these, if you'd like. I've been thinking of doing a couple projects with some and had been doing research on types. Too funny that you're looking for them too . I figured I needed more projects for all that spare time I've got kicking around .

Barbie

 

[returnofsid]

LOL Barbiie, sounds like a plan. Which particular sizes are you interested in?

 

[Barbie]

I'd like to try a couple sizes of the coated ones, I think. How many were you thinking? I'm afraid I'll go mad with them if they work the way I think they'll will .

Barbie

 

[returnofsid]

Well, still a bit unsure of the holding strength of the 1/2" X 1/8" epoxy coated, however, I'm willing to order a few and try them out. That's the only size I'm sure of for now. Would also be willing to try a couple different sizes or shapes for that matter. of the 1/2"X1/8", I'll probably want at least 10-20. LOL Do I need to narrow that down a lil' more? Also considering going with ceramic magnets on the inside and the rare earth magnets on the outside. What are your thoughts? That would cut cost down some, although it's not an amount I'm particularly worried about either.

 

[returnofsid]

Hmmmm....maybe the 1/8" thickness needs to be upgraded to a thicker magnet. Now looking at the 3/4" by 3/8" though that does up the cost considerably. Standard 75 gallon...using to make frag racks. Sure don't want frags all over the bottom of the tank in the morning. Any thoughts?

 

[mfinn]

I'd try a couple of the thicker magnets, atleast for the outside of the tank.

 

[Barbie]

I was going to use them to make frag plugs and I was thinking they had to be at least 1/4" thick by 1" or so to be effective on anything over 55 gallons. I'm still looking for more info though, so I planned to try a few sizes. This week is that Catfish Convention so I'll be in Baltimore until next Monday.

Barbie