on a tank that small with MH lighting and a t3/4 pump, I would think your water temp would hover in the mid to high 90's. those pumps are horrible for heat transfer!!! A mag 7,9,or 12 would be a much better bet, and reasonable in price... There are other inline pumps I would recommend but they are very spendy and you seem concerned about cost. that t3/4 pump with a fan for cooling would still cook all your livestock, unless you had a wind tunnel of fans over the tank and topped up about 3+ gallons of evaporation a day while having the sound of a jet engine in your living room....
my personal opinion, those pumps are not worth their weight in feces....