Please do a compleate test of all water paramiters and post them, This will help to determin if it is ok or not. Include ammonia, nitrite, nitrate, phosphates, and ph.
Although RO water is recommended, it is not necessary. Many people run their tanks without the use of RO water. Even my buddy's reef (gorgeous reef at that) tank has been running for years on his apartment complex tap water.
Is RO water a good investment? Absolutely. I would guess most reef keepers would highly recommend it. Is it still possible to have a FO, FOWLR or reef without ever using RO water? Absolutely. But if you want the best for your tank (and probably the least amount of problems), at least RO or RO/DI water is the way to go.
Edited to add...you can raise your pH with marine buffer. There are a few brands to choose from. Here is just one I found by doing a simple search:
id use amquil its a bit better but almost the same stuff...i use tap in my reef...i alter it a bit but no Ro i might get one but my reefs have florished for over 2 years. but RO?DI is best in the long run unless u can chemically alter it otherwise
yor ph should be above 8.0 between 8.1-8.4