You can clean it pretty well, and in such a design the rockwool would most likely take up most of the salts since they are the primary filter. Deposits are always an issue, but calcium is also a good buffer. If its allowed to soak in a sump like system and you hand wash it, you can recycle. If you don't believe in that, you can buy it for $3.25 a cubic foot at a landscape supply company like I do. For $20 I bought enough lavarock for a dozen 5 gallon buckets.

If its got lots of good drainage, and it floods and drains like so, it will build less than if you had a drip or something. I'm really trying to go towards a non-chemical approach towards this so I don't get salts and such. I'm working on a project with microbials and chemicals in 1 system. I'm familiar with bacteria from aquaponics and know their importance. Its just about putting a buffer between the bacteria and the deadly chemicals.

Heres a picture of the 40LB surge in action.

:jointsmile: