Another story for you ,
Started a 10 gallon tank about 6 months ago , was my first tank and set it up with tap water and used tap water for top ups for the first 2 months. Had purchased a cheap 20 dollar test kit which were strips , again i didn't know any better and the readings were always good.
I actually got lucky when i consider all i have lost up to the 3 month mark was
20 bucks on a clownfish
45 bucks on 3 frags (one i was told wouldn't do well with my lighting , i got it because i wanted to try anyways , so double my fault)
Have since upgraded to a 40 gallon hexagon tank , still needs some more LR and well everything lol.
Used R/O water from a local water store ( i got dirty looks for about 8 stores around my area when i asked for RODI water , they said RO water is the best you can get)
My not so local salt water fish store sold me 40 gallons of premade RODI salt water for 20 bucks , was a pain to travel with ( takes about 35 minutes to get home from the place)
But it was well worth it , all my corals looks better , my fish seem brighter and my tank looks cleaner then it ever has.
Will get an RODI unit eventually ,
SpectraPure Water Purification Products
heard great things from that website , also cheap.