Whats my tanks problem ( turbo snail and zoas ... )

[Berkay]

Hi ? 

my tank is about 2.5 months old. 

It is 18 gallon. In the tank , there is 2 fishes. Percula and clown percula. Sand starfish and 2 conches one is new. 

I added a conch and a turbo snail 2 days ago. But turbo snail worked about 5-6 hours and it stopped. It Staying on the sand. And it stay wrong way , i can see under the snail. :/ it cant climb i dont know why ? And new conch is now fully in the sand. I think they dont like the water but what is wrong ? 

8-10 days ago i got cyano problem and i did %20 water change , used biodigest. Tomorrow i will do again same think and will use biodigest again ? Is it ok or wrong ? There is algae problem and cyano problem so , bacteria may work nice. (not bioptim ! ) 

kh :9.3

nitrate:3

phosphate/nitrite/ammonia: 0 

pH 7.8-8.1

salt:1024

tds 0 

all with Salifert. 

I got led and 2x24 t5 but during cyano and algae problem i closed the lights. I got little zoas they are not so happy like snail and conches. Here the picture of situation. There is no alive for clean the sand bad for algaes so ım cleaning with syphoning. ... 

thank you  ✌️

[Red_Blenny]

Did you drip acclimate your snails?

[Berkay]

3 hours ago, Red_Blenny said:

Did you drip acclimate your snails?

Yes about 40-50 minutes. 5 ml water adding each time per 5-6 minute