The only immediate problem I see that is a possibility is that it may have an open current of electricity. The easy way to find out is to simply stick your hand or a finger in the water and if it shocks you, there is an electrical current coming from the heater. My old aqueon heater had a crack on the bottom causing the electric current in the water. If there is a shock it won't harm you unless you have a pacemaker or something to its equivalent. It will scare you more than hurt you lol trust me 100 watts isn't enough to damage you, I got shocked by my 300 and it just scared me but I wasn't hurt by it. But if you don't have a shock I guess it's okay to use but I'd still go pick up a different heater brand.I am treating them for ich. The heater is working right now. This is just so frustrating having a second heater leak. Could it cause a problem?