I used 5 gal. buckets on my first grow and adding water every day was a pain in the ass,temps were also a problem I had to deal with,now I use a large cooler for a res with a pump hooked up in there to circulate the nutes through the buckets that are linked togeather.with a few shut off valves and a few more fittings my res changes are easy and so is final flushing,linked buckets with a res is the way to go