I've never seen either system, but I imagine they are designed for just one season's use with a very weak fertilizer solution or perhaps fertilizer is just added to the reservoir every 3rd time it's filled ... If they're not over-fertilized, salts shouldn't accumulate.

Hey Bubba,
I build my own self watering containers which i base off of the earthbox. I added a drainage tube, so every month during the growing season I can pour out all of the water and refill with fresh H2O. The real advantage for me is that I rarely ever have to add water to this container and I get huge plants. Not sure if it's the constant water source or the large container allowing for deep roots, but I fit 2 pepper plants in each 18 gallon box and the result is hundreds of peppers on giant bushes. I've used it for 3 seasons in a row, you just have to clean it out and bleach it each year. Costs about $10 to build when you can find cheap boxes.

Here are similar plans: http://www.josho.com/gardening.htm

I also use these plans for global buckets, I get great results here as well. http://www.globalbuckets.org

Here is a link that might be useful: PEPPERMEISTER!