Hi, apologies if this is in the wrong place but I could do with some advice. I have a 75l tank with a mix of small fish guppys, tetras etc. The tank currently has an issue with snails! A rogue one turned up on a plant I bought and now I have 100s! I've bought 5 assassin snails and they've helped a little but they're still a problem. Is there a recommended amount of assassin snails based on tank size? Should I buy more or is there another route I can take?