Adding sand sifter to clown tank?

[Moose.Jy]

Hellos!
Looking for some advice on my clown nem tank.

I have a 20 Gallon aio tank set up, run a AI prime for lighting. in it are two juvenile ocellaris, two Ultra Rose BTAs. (Ones tiny it's a fresh ish split) and about 15 cerith snails and 10 nitrite snails. Can't forget my glass fogging amount of copepods I over feed phyto to much ('-__-)

-Fully cycled this tank was a Lps frag and cardinal fish tank b4 they all moved to our bigger tank.-

Anyway as the tank is older but the nems and clowns are new I was wondering if anyone had some advice for-first long term success on a clown nem tank, I'd really like the BTAs to cover the rock over the next few years! ... And for my clowns to live to see it lol.
Second - sand sifting goby addition? I want to possibly add a Twin spot but I'm concerned that first the clowns will harrase it as soon as it hits the tank, or the same thing but it will be in 2-3 years when they are full grown. (I do have a 2" sand bed so goby depth ✓)
Is a 20 big enough for them to share with a sand sifter? If not is there a nice alternative, different types of snails or a star... Please don't say hermit's their need for new shells gives me anxiety that I'm failing them.
My end goal is a small simple tank that is easy to care for, for a long time. The big ever evolving tanks just aren't my thing. (Our big one is my mom's I washed my hands of it, till she needs help lol)
Really worried I went to small tho. I know people keep clown pairs in smaller even but I don't see many examples of those tanks being around 6 or more years later.
Thanks to anyone who replies!

 

[SnazzyUrchin792]

I just added a YWG to my 20g damsel tank. Some tips: 1. Give it hiding places. 2. Introduce it at night. 3. A pistol shrimp would give it more confidence. 4. Rearrange the rockwork before adding it. 5. Give it time.

 

[D-Nak]

All gobies are not created equal, and your success really depends on which one you pick. For example, the twin spot is typically passive, and if the clownfish are well established and paired, they may be extremely territorial and could pick on it, as you suspect. Most sand sifting gobies--particularly sleeper gobies-- slowly wither away because they starve to death. A 20 gallon tank won't have enough to sustain a sleeper, unless its eating other foods. Furthermore, many gobies are easily spooked, and often jump or may accidentally dart into an anemone (which could kill it).

If you do choose a goby, I'd recommend watchman gobies since they typically don't actively feed (meaning they're not causing much of a distraction for the clownfish) and tend to keep to themselves.