Yeah, I know you want the tank for frogs. What you do is get a pile of rocks and silicone them together to make a removable divider. Let the silicone,(aquarium grade), dry for a couple of days and put it in the tank half way along and fill one half only with gravel. when you fill the other half with water it will seep through into the gravel 1/2 of the tank keeping everything nice and moist. If your species of frog needs heating you can use a low wattage aquarium heater in the water filled 1/2 of the tank but put a heater guard on it to stop little froggies from burning themselves. Get a piece of driftwood or bogwood and drill it up the centre so you can put a tube up through it from your filter pump. The water gets sucked into the filter, cleaned and then pumped up the tube and trickles back down the wood onto the dry, (moist), side of the tank where the gravel acts as a secondary trickle filter providing the aerobic bacteria necessary to help combat the ammonia and Nitrite levels produced by high waste producing aquatic animals such as frogs. an ultra violet lamp should be provided for the best welfare of your little froggies but if you do this you will have to discard the tank cover glass and provide a tight fitting mesh top to the tank as glass filters out the U.V. rays. Dont place the fitting beneath the glass tops as the frogs WILL get into it and either fry themselves or electrocute themselves.
OK, I answered, now I think you owe me a deletion in the other forum??