I have this 20 gallon tank that I am starting up and it has cycled and is growing the algae that snails and hermits eat(green film algae), the salinity is fine the nitrates are 5-10ppm, which is about where my other 20 gallon which is doing great is at, the only differences in the tank is that the mature tank has a cheap skimmer that everyone tells me really does not help, yet i keep putting turbo snails and margaritas in and they keep dieing, is there something maybe I am missing