you might want to change your brand of salt..
do check out brands like DD H2Ocean, Tropic Marine, Marine Environment.. etc..
dont use those hydrometer, get a refractometer.. as you can tell, 3 different hydrometers give u 3 different readings.. haha..
and do not use tap water as it contains elements like chlorine, silicates that will be "harmful" to your tank in the long run...
do use DI or RO water instead... you can either purchase them, or you can invest in a RO/DI Water Filter instead... no amount of test kits can help if some of the fundamentals are not adjusted right...
starting off on the right foot will save you alot of unwanted trouble in the long run in future.. you wouldnt want to purchase your favourite fish or coral only to see it die off because of the mistakes that you've failed to correct right from the start... dont learn it the hard way, im sure many experienced reefers here would be more than willing to help you...
Happy Reefing