20H stocking.

So I did a post earlier about stocking questions for a 10gal, but I've just moved some things around and now I have an open 20gal hanging around. I'm planning on doing a 25% WC every week to every other week. I'll be having a protein skimmer eventually (don't know what type) without a sump (no space). Is this a good stocking list? If not what would you suggest? I already have the clown goby in my 10gal.

Fish:
Occelaris clown x1
Yellow clown goby x1
Red/purple firefish x1
BangaiI cardinalfish x1
Green chromis x1 (if I have space for it)

Inverts:
Blue leg hermits x6
Porcelain crab x1
Tuxedo urchin x1 (I think it will eat the coralline algae, right?)
Skunk cleaner shrimp x1
Peppermint shrimp x2 (if I have space and if they'll get along with the skunk and corals)

I'm planning on turning it into a reef setup later on down the road. I actually got two zoas on some live rock.

[Edit]
Also, is it okay to use play sand for a sand bed, or would that cause a diatom explosion from too much silicon? If so, is there something that will readily eat the diatoms?

 

Bumping this up for you

 

Bumping this up.

 

Bumping this up, again.

 

I would suggest getting a 20 L instead of 20 H, fish much rather have length than height, from the fish list I would just drop the chromis. The inverts look good to me. I would definitely not use play sand for it, just use live sand that is meant to be used for reef aquaria, or you could even go bare bottom. I think if you keep up the water changes, you will probably be ok without a sump, but a sump is really a nice way to hide all the equipment, including the protein skimmer, and possibly carbon or GFO.

Cerith snails eat diatoms, but I wouldn't be too concerned about them, as long as you use ro/dI water, and let the tank stablish itself, they will disappear in the first 6 months.