It's def a + to not spend $ on the initial set-up, I didn't destroy my wallet but I do spend waaaay too much at my local SW fish store without thinking twice.
FOWLR means Fish Only With Live Rock & FO means Fish Only. I have a 55g FOWLR currently, love it to death, been up for only a few months but is my favorite thing (don't tell my gf

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Nice corals are more sensitive to salinity, lighting & water params but it's def a rewarding thing. Being fairly new to this, like you, I feel that if you start slow with easy corals, polyps, & mushroom, you can work your way up as you get more knowledgeable about everything. I am currently experimenting with low-light polyps and corals that my single fixture can support.
Here's some tips I picked up starting up maybe they'll help a bit:
- wait for your tank to fully cycle before adding any livestock
- stock your tank slowllllly & research prior to purchasing, rushing will only cause your tank to crash or cause issues with inverts/fish compatibility
- test salinity often (FOWLR/FO 1.022-1.025 & Coral/Reef 1.025)
- use 1/2 cup of salt per gallon of water
- pre-mix your saltwater for at least 24hrs before a WC (using a powerhead & heater).
- test salinity & temp prior to WC to match as best you can to tank
- get a Rubbermaid BRUTE container for mixing (grey/yellow/white only)
- top off your tank with FW not SW
- make sure your circulation is good, you want 10x gph flow based on your tank size.
- RO/DI water is a must if you're going to do corals/reefs, you can get away with dechlorinated tap water in a FO or FOWLR but may run into algea issues depending on your water quality
best,