1st off DON'T GIVE UP!!!
Second slow down deep breath.
I would say get rid of the Bio wheel NitrAte factory , next do a small water change no more than 10 gallons each time and no more than maybe 2 times a week ..... Do check your water sourse for NitrAtes, Phosphates, and ammonia , if you can not get RO
water dont panic we use distilled and have had no problems (I could get RO
but I am not paying 3.50 a gallon !We rent so a unit is not gonna happen either...)For mixing salt water up what worked for me is mix the plain H20 for 24 hours on the 24 hour mark add your salt 24 hours later check your SPG , we never used a heater in ours but when I did a change on our nano I dripped it in at a rate of 4gtts per second through our filter where the heater is and that is where it would mix with tank water.At one point and time or another we have all hit a brick wall ...and felt like we were off. Now Never never never trust a LFS
, get your kits and do your testing at home I have the aquarium pharmasutical kits and they are pretty easy to use , you may need to have them cross refrence your findings but that should be about it . They are there to make money bottom line they dont care if you are sold something that could damage your system . Most ammonia locks and such are fresh H20 only . You could try purigen , phosguard , or chemipure to help ya to settle things down a bit ...As for the bacteria to use I have use the biospera with eh results others swear by it ,dont get cycle this has been pinned as causing algea in salt water tanks .You may need to do a restart but I dont think that this is the case. Remember we all go through tough times at some point anyone who tells you other wise is a liar !I will be the first to say when I firs started I crashed my tank too and had listened to the LFS
while it crashed !