Advice, 120 Gallon Freshwater Tank.

[Hamsnacks]

Hello,

Currently have a 30 Gallon Tank with 2 Blue Crayfish, looking at expanding.
There is a seller online looking to sell his 120 Gallon Tank with Stand, Marineland Filter, space media, air pump and 2 light ballasts. For a pretty fair price.

The tank is 5' Length, 2.2' High, 1.5' Deep/Wide
The filter is a Marineland C-530, it does 530 Gallons per Hour

Other than the decorations for the tank, any other equipment needed to run this tank?

In terms of fish, I most likely will be going the Rainbow Shark and Bala Shark route, and maybe a few other smaller fish with them, ones that are compatible.
So my second question would be what would you recommend in terms of maintenance, how often would you change a percentage of the water? Do these filters last a long time? Is the electric bill going to take a big leap or won't be that noticeable?

Any other advice would be helpful, including any other stock you would recommend in there.

Thanks in advance!

 

[FinsandFeathers]

You're electric bill will go up a bit, but more from the larger heater than the filter. The most economical heaters I've found are titanium rods with external thermostats. They cost a bit more initially, but will save money in the long run on electricity.
Water changes will depend on your stock level. I have several tanks running, from 29g to 180g, and usually try to do a 50% water change on all of them every week to 10 days.
I would start testing the water a few days after yo get it fully stocked, and use judgement based on your nitrate levels. Once they reach 40 ppm, it's time to start thinking about a water change. Nitrite and ammonia should always be at zero, of course.
That's a good sized tank, and bigger tanks usually require less frequent maintenance than smaller tanks, so you may be able to go every couple weeks, or even longer if your levels stay low.