|
Dr. Bob,
I am taking the winter months to
plan a remodeling of my homemade filtration system. I'm considering
switching to bio balls from lava rock because I feel it has
not been providing the maximum filtration. Can you provide
any insight into if the size of the bio balls used will make
a difference (1" or 1.25") or will it end up providing the
same surface area because of additional smaller balls in the
same filter space? Additionally,
approximately how many I should use (I know there has to be
some sort of formula).
The demographics on my pond are
approximately:
- ~5700 total gallons
- ~5125 in main pool for koi and
goldfish (remaining gallons in collecting pools and stream)
- 6-8 larger sized fish (ranging
in size 10" - 14")
- 8-10 medium sized fish (6" -
8")
-
8-10 smaller sized fish (1" - 5")
Thanks
for your help,
Robert
Rob,
Don't wed yourself inextricably to the
idea of bio-balls, although you are quite correct about lava
rock. Remember that the idea with filter media is to get the
best ratio of surface area to cubic footage of media that
you can. Other important considerations include resistance
to decomposition (which is where lava rock fails), resistance
to fouling and channeling, ease of handling, and cost.
Lava rock fails
in all of these categories except cost, and you pay for the
cheap material in bulk, weight, decomposition and instant
fouling.
Bioballs are light,
but expensive, and are a pain to handle. If they escape their
container, they tend to roll everywhere. When they foul (especially
with hair algae) they are a pain to clean. They also float,
and if you get an overflow in your vat, they go everywhere
again. They also do not give you the best bang for your buck
when it comes to surface area. If you are feeling flush, Kaldenes
media is currently the best surface area to cubic footage
ratio you can get. Put a bunch of high-volume air through
it and it won't foul, either (see Bioreactor!).
For less money, and no need to redesign your filter, Biofil
(otherwise known as PVC tape) is a great bargain. It gives
you 125 square feet of area for your bugs to sit on for every
cubic foot of it you buy. It sinks, and is ridiculously easy
to clean (simply shake it out in a tub of pond water).
For the "miser
option", go to your local flea market and buy a couple of
huge bags of "Tuffy" sponges (you know, those plastic mesh
scrubby thingies) and use those. The Aquatic EcoSystems catalogue
has a comparison table of filter media.
Bob Passovoy
President
MPKS
|
