If you are like me who needs to mix additives to maintain Ca, Mg, Ph, Kh in your tank. You will know how difficult it is for some of the additives to dissolve in DI water. Of course you can just dump the additives in your sump but it can do more harm when the additives don't dissolve fast enough and lands on your corals. I'm lazy to stand or sit around to stir the solution until it mixes completely, so I've decided to DIY a magnetic stirrer. This is used in labs to mix chemicals. Basically it