28
»
-.
‘
Table 4. EVALUATING AVAILABLE METHODS FOR THE SECOND STAGE
ÏÎ
OF THE NITROGEN CYCLE. (CourtesAquarist and Pondkeeper .)
_
Method
Disadvantages
,
Comments
_
Siphoning
Removes only visible detritus which
Useful for removal of large
_'
and manual
can be reached by tools used
pieces or accumulations
_
removal
only
-
Mechanical
Does not remove large pieces, and
Reduces turbidity where
-
filtration
only those small pieces which the
inhabitants dig or are _other‘'
water circulation system brings into
Wise messy. Strong continthe filter. Media must be‘cleaned or
uous action possible
'
changed frequently. DisSolved
organics remain
‘
"
_
Activated
Only holds di3solved organics and u
Extremely efficient when :
'
carbon
does not change
‘full’
properly operated.”Carbdn
can suddenly release large quantitieS
can be reused if subjected
‘
of dangerous substances into water.
to steam—pressure cleaning.
Carbon must be changed“ frequently
Helps minimiSe urine con.—
'
_
’
and washed first to remove
May tent.
,
-
:
remove medicines and other additives. =
'
.
Less den’se than water.
_
_
_
.'
_
‘
Water
_
Hard work. Partial
.
{for
einer—"—
'
-
Ÿ
l
7
‘
.
frcèq1}enfadditî<äñ
gencvsüuatwns
Where
’
’
"
always beneficial. Complications Withapollutantlssynthetlc
.
andterÿèi*ature
'
-
‘
"
:î_,-j_zçf
Î ï
-_
'
_
in
*
.
*.
î
.
Ï _
=
Tori ex and study
«
.
from salt water. Subject to 'fouling‘by of
.
1
organic substances Which the resin » » is essential. N‘ôt gènëi*ällÿ_ .
…
…
does not
recommended—.
'
-
…
_
-.
_
Of the resinsane directly toxic them—_
, _
_
.
'
or have-adverse effects on the
-
-
'
'
Air—shipping MaymcreasepHvaluebvremovmgOxygenatewateratsame .-