The levels in the made salt is not an issue as long as your storage tank is clean. I do keep a pump in the tank constantly moving the water. As someone else posted when you use the water just make sure the temp matches your tank temp.
I mix my salt just after a water change. I have two water tanks one that auto fills with RO water and then I transfer the water into my salt water gilding tank.
My water sits mixing for upto two weeks before I use it
Flow! If you prevent settlement the aiptasia will die. It looks like you have 2 mp10 in the tank. Bring them down lower or add a power head or two blowing bottom to top. This will move the sand around however the aiptasia will be gone in a little bit.
Yes I have a PAR meter and a LUX meter. MaxSpect says its good till about 24" and yes it gives a much lower PAR reading compared to the Pacific Sun 160w fixture and a lower PAR reading per wattage rating compared to the AI (the AI I believe is only 72W). IF anything the AI has the highest PAR...