It is sometimes normal for zoa to stay closed for few days or even weeks when introduced into a new environment. I would suggest to leave them alone and just monitor for signs of melting or rotting ..
It is when u see that they are melting or rotting or getting covered by a layer of white fungus then they are dying.
All sand will scratch glass , be it suger fine or grain size or boulders ... Difference is the scratch itself sugar fine scratch , grain size scratch or bloody obvious ####%¥¥xx<# scratch (which I have)
All marine LFS should sell snail!!!!!! Turbo snail and ,urchin will eat diatoms !!! .. Worst case u go beach collect some snail from the water breaker rocks!!! ..
That's the amount u need I guess, those additives are to maintain lvl not to raise . Try sodium bicarbonate for kh and calcium hydroxide to raise calcium then dose those additives to maintain.
It could be the air input or the water output either one chokes the water lvl will rise and overflow the cup ... maybe it takes a knock to choke and Unchoke any one of the 2 .
No harm checking both .