I just started following your thread rellikdloc, i noticed you were having heater troubles. I too use the Marineland visi-therm heaters (great choice of heater). You may have purchased a new one by now but i wanted to let you know, Marineland has recalled these heaters and petsmart emailed me the other day about the recall.
this is what the email stated
Dear Valued PetSmart Pet Parent,
Marineland has issued a voluntary withdrawal of the Stealth PRO Submersible Heater (100, 200 and 250 watt). The product is being withdrawn due to a quality issue.
If you have this product, please stop using it immediately and take the following steps:
1. Unplug the heater from the wall to stop the flow of electricity
2. Let the heater cool for 15 minutes
3. Remove the heater from the tank
Please bring the product to your closest PetSmart for a full refund or exchange. Replace the product with a comparable heater as soon as possible to maintain the temperature of your aquarium. A PetSmart store associate can help you select the right heater for your aquatic environment.
If you have questions about this withdrawal, please call Marineland Customer Service at 800-526-0650 or 800-432-6986.
At PetSmart, we are concerned pet parents, too. We will continue to do everything we can to help you and your pet during this time. "
If you got your heaters from petsmart, go exchange them. If you didnt get them from petsmart, you may wanna take it in and see if they'll swap it out... pull the "I lost my receipt" routine. Worth a shot, or at least get money back for one and call marineland for the other.