Treasure Hunting Magnet Size Discussion
Hey - This is a great Thread I had to try mostly by Trial and Error for the best size, it really depends on what your situation is. I'm not sure if I agree with whoever is selling these Russian magnets, some of his comments don't make much sense, it could just be translation though.
I only use Neodymium magnets as the weight to power ratio is far better which means you can much more easily feel any hits that you have while you are fishing in the water. Therefore I prefer a smaller magnet around the 100-120 lb pull force for my main working magnet it is pretty light and you can easily feel when you get a lure or even a bottle cap or coin. It's best to just jig it off the bottom which seems to be the most efficient movement and 99% of the time the pull force will be more than sufficient.
Always look for the most compact Magnet, lowest surface area to pull. The wider a magnet gets the less balanced it is and therefore you get a lower practical pull force, especially on the smaller uneven items that are found 99.9% of the time. Think of it this way, if you have a big wide magnet it will rotate off the center easier when pulling up an object which effectively lowers the pull force and begins to rely on friction between the magnet and the object which is nowhere near as effective. It is much easier to slide a magnet off the refrigerator than pull it away perpendicularly.
I always bring along a larger magnet in the 400 lb range just in case I get something bigger, but much larger than that and I don't really want to pull it up and deal with it, too many chiropractor visits, ruined clothes way too much mess for me and not practical unless you are Arnold Schwarzenegger. ("I let him go." Quote) The heavier magnets also greatly lessen the feel of the hit when an object is originally pulled to the magnet. You won't even know that you get a smaller object until you pull it out of the water. I almost always find objects first with my smaller magnets (100-120 lb range) then just pull out the big boys when needed. The bigger ones are also more expensive and there is always the chance that the rope comes loose or the magnet get's wedged in debris and lost etc.
Something else to think about is that I really like to just carry my magnets around so that I'm ready to do a little fishing at lunch etc. but they were so dang annoying to carry around, stuff jumped to them and no way I would carry in my pocket or just let the kids play with them or even showing them off at the office usually meant people got scared of them because scissors etc would just fly to them. Now I have some that come with covers which I love, they can be carried in your pocket, glove box or even tacklebox without stuff jumping to them all the time. Can't tell you how many cuts I have on my hands and pants from the magnets opening my knife, well worth the couple bucks more to get something quality which was designed for convenience. Wish I would have done them sooner. I don't know how to link but I just got a picture on Etsy. I would suggest picking up something with a protective cover or design something yourself, I'm just too lazy to put all the extra time in, it made my life way easier and I go out more and find more stuff because I have it with me all the time. The ones I have is called Tacklemag S from MagPowerDesign on Etsy which I really like, there are a couple sizes/shapes, but it's up to you, there could be other brands as well.
Also, put the magnet into a plastic bag; then "burp" the bag and tie it around the mag. That way, you can clean the trash metallic pieces from the mag by simply removing the bag. That goes for recovering those Canadian coins, too. 
