How many spare parts do you have?
 

As the title states do you have a collection of spare parts or do you toss as you go?

I keep spare parts for everything critical so I don't need to panic shop. Seriously, everything.
Return and skimmer pumps and impellors; doser pumps and hoses; heaters; power heads; MP10 wetsides, power supplies and a controller; QT light, filters, media; DT socks; bulbs and a ballast; ATO and pump; controller power bars, cables and head unit; test kits; chems; glue; putty
The list goes on ...

I literally have around 400 sqft in my basement filled with old parts, tanks, reactors and aquarium junk...

I don't necessarily keep everything, but if I replace a T5 bulb that hasn't burnt out but is just old I won't throw it out. Always good to have a spare :) I have an older BK mini 180, some quietones pumps, powerboat goodies... all kinds of stuff in the basement.