Moving a fish tank

I have to move my 29 gl & 10 gl, I am giving my mom one of my 55 gl tanks
and its on a rod iron stand, it has a place for another tank below which is
where I have my 29 & 10, I am moving them so I can give her the tank and
stand, sucks because I have another 55 down stairs not set up but she wants
the stand also, we would of had to move it any way sooner or later because
its in the best place for the 120 gl tank to go.
What I am wondering is in the 29 gl should I keep most of the water or
replace it, it should not take me no more then an hour to take down and set
back up so the filter should be fine in the 29 gl, I have both 5 gl & 10 gl
buckets so I could keep at least half the water in the tanks. This tank has
been set up for 3-4 years.

The other thing I am wondering about is in my 10 gl I posted the other day
that i had put an UG filter in it to work with my HOB wisper about 2-3
months ago, since its a guppy tank and quite often have fry in it i turn
down the wisper and the UG picks up the slack, Kio-lo said junk will gather
under it, i am able to see under it by laying on the floor and i checked
last night and dont see much of anything under it, i guess because of the
HOB wisper gets most of it, plus i vacuum a lot, but i had as of yesterday
lost 2 guppies 3 weeks apart, last night at feeding time i found one more,
the three that have died are from the group i got a few months back that
were sick, all my original ones that i have had for about a year seem fine,
for that matter i dont see anything wrong with any of them, or anything
wrong in the tank, i was planning on replacing all the water in the ten, as
long as i dont mess with the filter would that be ok, or will it start to
cycle again, its been set up for about a year.
nik