*muffin* wrote:
... but you guys totally EMPTY your ponds to remove the gunk??? big ponds
3000 gal ones?? on, where do you put the fish??? ...

Warning: Long answer. Our pond's previous owner and designer cleaned our
3500gal pond each spring, emptying it completely while holding the fish
in a kids' wading pool. Almost everything I've read since becoming
interested in ponding has said not to do that. So for a couple of years
I tried different types of vacuums made for ponds and swimming pools,
but after three years and about eight raccoon raids (they push potted
plants into the pond, the koi empty the pots that are not already
emptied, bottom gets covered in potting soil, rocks, etc.), we decided
to completely clean the pond. (We don't have a bottom drain, but I'm
hoping to put together a DIY bottom drain and skimmer this summer.)

I didn't remove the koi because I didn't have a place to keep them, so
only took the water down to 3 inches in the shallow end so they could
continue to move around in the deeper end which is 12 inches deeper. I
used a Python water changer (used for aquarium tanks) but I duct-taped
the siphon tube to a piece of sturdy PVC pipe (siphon tube outside pipe
-- tried siphoning through the tube but lost a lot of suction power that
way) so I didn't have to spend days bent over the short tube. It didn't
work well with large leaves or twigs, but those usually piled up in the
tube so I could reverse the water and shoot the leaves out onto the
lawn. The Python also didn't pick up the gravel and rock, but once I
could see just rock I used a swimming pool leaf net to scoop those out
of the pond. I lowered the water gradually over 2-3 days, spent about 5
hours with it at the lowest, then gradually refilled the pond with
treated water over 2 days.

I also took advantage of the low water to catch and remove all the
shubunkins in the pond; their population doubled or tripled each year,
and in that time we only had one surviving koi baby. Within a month of
removing the shubunkins, we had hundreds of koi fry.

Without a bottom drain, mulm and leaves pile up at the bottom no matter
how much I net them or how long I keep nets over the pond in the fall /
winter. So this year I'm using a 16gal shop vac with the built-in pump
for pumping away the waste water. It's slow going because of suspended
particles in the water reducing the visibility. Plus the rocks I used in
the planters (which were dumped by raccoons, again!!) gets stuck in the
vacuum tube. I just put together a suction head with slotted openings
this week and will report on its effectiveness soon. I put a mesh bag
inside the shop vac body (tied around the inlet pipe) to catch rocks,
leaves, twigs, and anacharis. Doing that helped increase the time I
could run the pump-out feature without rinsing the fine filter leading
to the output hose. Because I'm moving the vacuum slowly and only taking
out about 1/5 of the pond water, the koi aren't effected by my cleaning,
except they love to root around in front and behind the vacuum head to
see if I've dislodged anything tasty. True pond pigs!!

If you don't have a bottom drain, I recommend putting one in if you
decide to empty your pond. Retrofit or over-the-side drains aren't as
good as ones installed from the beginning but they can be done.
--
Kathy B, zookeeper
3500gal pond (Oregon)