Brown patches on sand bed

[DTheMan]

Hello Everyone,

I am new to saltwater aquarium and added two clown fish on over the weekend in my 29 gallon bio cube. Everything is going perfectly fine and fish seems to be eating and healthy. After adding fishes how long should you wait to do first water change? I am hearing anywhere from two weeks to 1 month. Also should I test water weekly?

Also I am noticing brown spots on the sand bed is that normal?

 

[vetteguy53081]

Likely diatoms which is often associated with a new tank and comes from silicates contained in sand, new rock and even expired DI resin
Although harmless can be unsightly
If so, lightly siphon and reduce white light intensity and even add snails such as:
Astrea
Turbo grazer
Nerite
Nassarius