What size CUC should I have for 20G

[ArrowCrab]

I have a 20g tank, about 12 pounds live rock and 3 dead. A about 2 weeks ago I added 3 hermits and an emerald crab. And 3 days ago a peppermint shrimp, skunk cleaner shrimp, and chaeto ball. I've seen posts where people have added as much as 1 or more snails/hermits per gallon; that seems kind of excessive to me, but then again I'm new and don't know anything. ;) So any recommendations? I've been wanting to add an urchin because I love the idea of them decorating themselves with stuff from the tank. But I'm afraid he'll grow to large for the tank or knock over some of the smaller less stable rocks. Any good small urchins I can get?

Also, right now how much should I feed the guys I have? I know they are all scavengers and such and will eat off the rocks, but I worry to much and have been feeding them flakes/pellets/frozen brine alot even with no fish in the tank. This combined with new bioload from 3 days ago seems to have caused nitrates to spike to 30ppm. I'm assuming that the chaeto takes a couple days to kick in before working off the nitrates?

Edit: Oh, and forgot the turbo snail.

[ArrowCrab]

bump

[Detroit_306]

i would maybe check reefcleaners.org and send them an email for what they recommend for a custom clean up crew

[Michigan Mike]

Just get a few astrea and a few nasarus snails and you should be fine. If you get too many they will starve. Everyone likes different stuff, I personality like my Stomatella Varia snails that came in my live rock.

Urchins feed on coralinne algae. Do you have alot?

As for nitrates - try feeding less and do a small water changes , if it's a newer tank give it time and what I just said...
Try to avoid overstocking the tank with too many fish.
You shouldn't have high nitrates with no fish. You shouldn't feed the cuc, they get the extra food fish don't eat or miss.

A picture of your tank would be nice, and info about it like your perameters and filtration, lighting,circulation,substrate, etc....