An aerobic septic tank sprays out the water that goes into the septic tank...somehow under the ground there is an entire system that separates the solids (they stay in the tank underground to be devoured by the microbes in there) and the liquids which are filtered through chlorine tabs and passed into another tank where all the liquids are sprayed out into a designated area...in our case our back yard...about once a day set by a timer or whenver the tank is full. At first, it sounded reeeeeeally gross to me(us) but according to the people from the South Texas Environmental Systes, if you reeeeeally had to, you could actually drink that water!!!!!! Of course, I can't think of anyone who WOULD do that but it is clean, filtered water. Ugh just the same. Anyway I guess since the septic tank isn't getting filled with solids and liquids, it doesn't need to be pumped out as often as a non-aerobic septic tank.
Hope that wasn't confusing and that I explained it correctly.
However....I've never been told to add salt to ours. We just add 3 chlorine tabs weekly down this long shoot by the liquids tank and once a month I flush a packet of active dry yeast down one of the toilet bowls...I'm guessing that helps to feed the microrganisms in there.
We were given a list of Do's and Don'ts for this system.
Some of the Don'ts are: Do not use liquid fabric softener...clogs up the microcritters so they can't live. Don't use bleach if possible in your laundry or down any other drain inside the house...but if you have to (which I DO!) I was told to make my bleach load the very first one I do that day...in this manner all that bleachy water can get flushed out through the system and into the yard with the water from the rest of the loads. Also Don't use anything that says ''Antibacterial'' on it...cuz this spells certain death for my septic tank buddies. Almost forgot...do not wash coffee grounds down your kitchen sink either...guess they can't be digested by the micro-organisms in the tank. Any of these 'Don'ts' can be done outdoors...as long as none of it goes down any indoor drains.
Ok...I guess that's about it...I appreciate any more info or anything anyone else would like to add...
Take care y'all...