Back in the hobby- temperature question

Hey everyone. So I'm back and just set up a 75 gallon tank. I purchased apx 80lbs of LR from an established tank about 2 weeks ago. My tank has been cycling and as of last night I was at: Ammonia-0 , Nitrites- 0 , Nitrates- btw 5-10. I also experienced a decent brush of brown algae while cycling but hoping I'm past that. So I have 2 aqueon 200W heaters in my tank. One I purchased new and the other I got off of someone. I had them both set at 78 Deg. I finally bought a glass thermostat for inside the tank and when I checked the temp it read 83 deg! I turned both heaters down to 76 and this morning my temp in tank was 81 deg. My question is, is this normal? Could it just mean that I may have to set my heaters at a lower temp to get the 78-80 deg I'm looking for? Or do you think it may be the used heater and I should buy a new one to replace it?



On a side note, with ammonia and nitrites both at 0 now and nitrates low do you think it's OK to add pods?



Thanks,

-Andrew