I have thought about all that and i have talked to alot of people on the site about it and right now in my mind the disadvantages or out weighed by the advantages i just now finished the overflow it has water running through it outside through a garden hose now will let it do that for a little bit to get all the glue fumes out i will taste some water from it later lol no fish water yet lol
but taste some water to see if i taste glue like you would if you repaird a water line in home. glue says potable water on it i used this same bottle on the last overflow i built and it worked great. as for diseases in my tank i never have had any i select healthy looking fish from a lfs
and acclimate them to the best of my ability. As for equipment i have a heater for my 55 and 29 plus two small heaters as backups in the system. the 29 gal
will keep all of its hob
filters and its heater in tank in case pump fails.