Its not a matter of if ich will come by raising salinity. Its suggested when battling ich to lower your salinity. After ich is suspected to have been cured you raise it back up. Typically people will move the coral out before lowering salinity that low. Needs to be around 1.024-1.025
So you need to raise it back up. Do this by topping off your tank with salt water like you normally would with rodi water.
As far as Kh goes it should be around a 9. Id recommend using api test kit, as its fairly inexpensive and easy to follow.
http://www.saltwaterfish.com/produc...ess-test-kit?gclid=CKq75-WAssoCFVKQHwodzJIKcw
Now I know this hobby is exciting and your lfs and everyone here recommends to use this product and that product. But it sounds like you are just starting off. The best thing you should invest into is a few 5 gallon buckets and some quality salts to mix saltwater yourself. Personally I used Red Sea coral pro salts. They have multiple trace elements that stay pretty consistent, so you won't get any unexpected swings of anything. Besides that you need to do more frequent water changes. I recommend at minimum a 20-30% water change this time. Following with a 5% weekly or 10%bi weekly or 20%monthly.
^^ This will fix your water perams to where you need it now this is why..
When you add food to your tank you are increasing your phosphates, which is likely the reason you have a bunch of algae. Feeding raises your phosphates/nitrates/nitrites which adds more food for algae to feed off of. So do frequent water changes. Another way to nuke algae, is using a phosphate nuker product, and also rasing magnesium to a high level of above 1600ppm(more advanced) will help eliminate algae. But to keep it simple just do water changes No algea= less work and happy zoas. Don't overfeed your zoas if you do spot feed them. Id recommend just letting them filter feed and not target feed so you don't overfeed them and kill them.
Red slime algea(Cyanobacteria), is not your typical algae, water changes alone don't get rid of it. Because it is a bacteria. You will need to use a product like
http://www.amazon.com/Ultralife-Products-Slime-Stain-Remover/dp/B0002DKB6S
IMO if you do this, your tank will thrive and look better then it ever has, and your zoa's will be blooming, cheers!