What are the optimum conditions for a freshwater tank?

The snails wont have any unusual effect on water quality in an aquarium, no different from any other snail or fish anyway.

But what they do is out-compete the local snails and shrimp etc, eat all their food and reduce their numbers.

What you could do to prove this is get two tanks.

Put some native snails in one, and a mix of native and invasive snails in the other.

Leave them for a few months, feeding both tanks the same, and then count how many snails are in each tank.

If the native ones that are alone have multiplied, and the ones with the apple snails haven't, then you have demonstrated the efffect the invasive species has on the local enviroment.

Ian

There is no one optimum freshwater condition, it depends on species you are keeping in it

ammonia- always 0

nitrites- always 0

nitrates- always 0

phosphates- low

chlorine- non existent

CO2- low to high depending on which species of plant or fish you are looking for optimum conditions for

pH: 4-9

Hardness- nill to liquid rock

Temperature- 50F-93F