calmag is mostly cal, so adding the 1/2 tsp of epsom with it, really helped me out a lot. I probaly only need to use epsom because i'm using tap water, but the calmag with epsom is working so well for me, im not changing anything! LOL
I dont think the idea was to cut washers out of the innertube, but to use them as spacer on each side of the ballast to keep it up and off the board. He has a pic of what he did.