lighting headache

[SteveConn]

A lot of my rock did that too. It takes months for a tank to settle. I started in June as a long time FW hobbyist with an established nano that I quickly crashed. My coraline mostly went white/died..then I had a diatom outbreak, then lots and LOTS of hair algae! I borrowed a Sea Hare from Red Coral, bought a Tuxedo Urchin, a Phosban reactor AND a lawnmower Blenny.. now my tank is pretty much algae free (I cant see any green algae at all, so feed the Blenny seaweed). My main tank now has coraline growing like crazy. One thing I found is that even moving rock will unbalance things and cause a die off of some of what was on the rock (reaction to lighting changes?) and I found the same with disturbing the sandbed much.
If you can, buy what you need upfront to keep your tank as stable as you can. Lighting, skimmer, auto top off, dosing pumps. A lot of people will sell here, so if you want to save, I recommend looking here for what you need.
For dosing, I use a Tunze ATO, but instead of plain (RODI) water, I use a solution of Kalk & Vinegar in water. Evaporation from my tank causes the ATO to dose. It isnt ideal, but it will work. I still check levels weekly (when I started I was testing 2-3x per week) and dose whats needed (SLOWLY).
Kalk & Vinegar mix is available online if you're interested. Its cheap and easy to mix.
Hope that makes sense! I know I added way more than you needed, but if it helps you avoid my mistakes....

Big changes/fast changes are your enemy, way more so than with FW

BTW: Welcome to SW!