New 29g BioCube advice and tips

[Lobbys Hobby]

Hello all
I am starting up a 29G Biocube... I was hoping to get some advice, comments, tips, whatever everyone has to offer from the pros here.
I had a saltwater tank about 6 years ago, it was given to me fully cycled and set up so I have some experience with salt but I am far from pro!!! When we were selling our house, at one of the open houses we had someone thought that maybe my tank was a wishing well... threw some pennies in, by the time I noticed what was going on it was to late everything was gone. I was so heartbroken that I got rid of it all.
So I am ready to start again (kicking myself in the butt for not keeping all my stuff) and was hoping to get some advice here.
Thanks in advance

[quick_murdoc]

Welcome to TRT! What type of advice are you looking to get? Do you already have all of your equipment? Are you looking for cycling help? Lots of knowledge in here from many experienced people.

[Loverotties]

Welcome to TRT! and ask away!

[Lobbys Hobby]

I have the biocube started (it's been running for about 5 weeks), have LS, medium and large crushed coral on the bottom of the tank, LR set up. Used RO water and have my SG at 1.020. PH is at 7.8 (is that a little low?), nitrate is at 0, nitrite is at 0 and my ammonia is at 0. I have noticed that there is some rust coloured growth on my rock and crushed coral, do you know what it is, and why it is there? I have the bioballs in the filter (but have read to remove them). Buying a skimmer this weekend. Also what is cheato a type of algea I am assuming, I don't really want to hang a light off the back of my tank for the cheato to grow in where the bioballs used to be, so what about putting it directly into the tank?
I was going to add a picture but it is saying that exceeds quota... not sure how to change it...