I have always used a PC battery back up...nice size one is about 150.00
I only plugged my filters in only...1 for every tank...Eheim 2217 would last about 5 hours on one.
The good thing is ur filter is plugged into it always...when the power goes out it aoutomatcally switchs to battery.
Eheim IMO is the best canister filter you can buy.
2217 is perfect for a 125....now what are u stocking the tank with....of course a HOB protein skimmer will round out a good filter set up.
A lot of people here talk about using one in QT/Hospital tank...thats not a good Idea...well as a Quarentine fine..but if medicating u MUST turn of UV...Copper will change to leathal heavy metal even at low doses
It can also interfer with many medications..so be careful.
UV Will kill Ich...But like was said..only what passes thru the UV gets zapped...and that depends on your DWELL TIME.
That means at say a flow rate of 400gph it will kill algae spores(free floating of course) but may do nothing for protozoa...u would have to slow the flow rate on the pump to say...
Looks like Ich or Oodidium..also
looks like a blockage in intestines maybe..feed more sponge/wet foods like Formula 1 or 2..lay off dry foods for a while.
That could be good...crack mite have been there so its not the stand..less worry about the new tank now.....Oh Yea..now...fix the old ..make a cynderblock stand....Oh yea!! 1 more tank in the garage!!
Love it when things work out like THAT!