I always pumped salt water from changes onto my lawn, in one small spot too as I never got around to getting a longer hose or connecting to the sprinklers. That section of lawn to this day is still the healthiest so I never saw any negative effects from the salt content. I probably averaged around 50gal a month from my 300 gallon system over around 2+ years. Often had large dumps of water in the 200 gal+ range as well from the numerous circumstances requiring such large water changes. I think it's ultimately still a small amount of salt given the rain and snow we receive each year, would highly doubt long term effects are really possible but I would suggest spreading it around to be safe rather than a single location.

So I gave them a call today and they suggested installing a dry well with some kind of specialized rock in the well. That specific rock will absorb all the the crap . It would be approx 6'-8' deep to prevent it from freezing during winter. Either way, there is a solution to my scenario which Im glad to see :)

do you have any ditches infront of your house or out back you could dump it? even with the well it might still leak out into the soil, I would suggest dumping it down a ditch or out back where you wont see any negative impact, installing a well will just take away $$$ from corals :)

Neighbors you don't like? ;pp

I'm surprised you've never had problems with you grass. There are parts of the Alberta and Saskatchewan grasslands that seasonally flood every year then dry out. Over long periods of time, this draw out salts from the ground water. In areas where they collect on the surface, practically nothing grows and look like white dusty patches in the middle of fields. For several meters out around them in every direction, the pant community is radically different from the rest of the grassland, favouring strongly salt adapted grasses and forbs. None of those species appear in commercial lawn seed-mixes, and Kentucky blue grass (the most commonly used lawn grass) haaaaaaates salty soil.

If you're not having any troubles, I suspect it's not that dumping salt water on your lawn isn't bad for it, it's that you've gotten lucky and the ground water/drainage dynamics in the area you've been dumping your tank water are working in your favour. Residential properties are graded to take water away from the structure, but that salt is definitely going somewhere, and likely not as far away as you think. Small volumes of water over short periods of time will likely have no effect, but with a large tank you're dumping the equivalent of 5 gallons of salt on your lawn every few months, depending on the frequency of your water changes. If you're lucky, that salt is going straight down out of the root zone and staying there, but if you're not lucky and it's spreading out in a plume through surface soil of your yard, you could be changing the salinity of a pretty wide area. You wouldn't see problems until salinity levels reached the tolerance threshold of your lawn, but once it does you'd be kind of hooped as it could take years for it to leach out.

If your'e going to be dumping salt water outside, you'd be wise to rotate the spot where you do it, and pick spots that are really well drained and drain away from your property.