2) add anti-bot text where you can show text randomly on webpage before they claim satoshi.
3) text they need to click in particular order.
These might help you against bots.
Search about captcha is what people use to prove it's a person some are better then others. I would guess your site is not worth a bot as paying to get capatcha solved vs amount paid I see losing money.
What is your current protection? And are you sure they are not just using something like ad-blockers which could effect your traffic on ads?
I am using google recaptcha service. but I am loosing my faucet's balance without any traffic...! I am checking my traffic on live stat tracker. It is not about Advertisments sir.