I'm curious about refill with phyton - do ya put the decloratinator straight into the tank as you fill it?
I did 25% water change while cycling my 127l tank. 75% changes are gonna be nightmare. I've very little space to get at the top of the tank
I tend to add the dechlorinater at same time as water is going into the tank using the python hose system
Dose for the same amount of water being replaced, not dosing for the whole tank water volume with Seachem Prime, but do read the instruction on the bottle of whichever brand dechlorinter you have, just to be sure.
I would recommend getting a python system or a simple DIY version using a long syphon hose and a universal pump.
You can get however long you need clear hose from LFS (clear hose/pipe is easier to see if water going through pipe or not rather than standard solid green or yellow garden hose)
For me, I got 10 meters of clear hose from a local Maidenhead Aquatic (costs a little bit but cheaper than buying a python system online), and a second hand eheim universal 600lph pump, not the fastest pump but fine for me as it gives me time to do all the other little jobs that needs doing whilst emptying / refilling tank.
First attach say 1.5 meter of hose with gravel cleaner to the tank and other end of hose to the pump (place the pump in a bucket in case of leaks), fill the 1.5m of hose first with water, and then switch pump on, ensure long section of hose is going to sink /bath and water will start going out of tank with the aid of the pump (you CAN do this without the pump but find it easier and quicker with pump).
Then for refilling, take pump off, long section of hose attached to bath mixer tap or kitchen sink, whichever works best for you, a tap or hose adaptor will be needed to attach hose to the taps, you can get a suitable one (adaptors do differ so you'll ned to find which will work best for the type of taps you have) you can get this from most hardware store or plumbing store etc
And other end of hose to the tank ensuring the water from tap is close enough to tank temp, a little cooler is fine but not warmer imho, and ensure you add dechlorinater whilst tank is filling (easy to forget!). Job done!
No carrying of umpteen buckets back and fro to bathroom / kitchen, even worse if have to go upstairs or downstairs with buckets!
So for an outlay of say £30 - 40 for everything including a second hand universal pump you'll then have a simpler version of the python hose system. Worked really well for me anyway.
A real back saver as well as a real time saver too, for me to do 2 @100 litres tanks, 2 nano tanks @20 litres each tank, usually took me about an hour and a quarter to half, all told start to finish.