THE AQUARIUM BUILDING
21
to five days and is at best haphazard. Sodium thiosulfate (0.05 gms. per gallon of water for 7 p.p.m. chlorine) is widely used for chlorine removal but it frequently breaks down and results in a drastic drop in
pH. If sodium thiosulfate is used, overtreatment must
be avoided and calcium carbonate should also be
added. A number of commercial chlorine-neutralizing
preparations are also available but are much more
expensive than thiosulfate.
SILT turbidity: Water from lakes and streams
is frequently very turbid. This problem can be overcome by use of a sand filter ( Figure 2 ) . The principal
requirements are a bed of sand and a back-flushing system.
FLOAT SWITCH FOR PUMP SUPPLY OR
FLOAT VALVE FOR ORAVITY SUPPLY..
APPROXIMXTE R/TE OP PILTR/(noi4
2&RM.PER SaFOOT
-.2 FT 8 AND.;'
\o,i X nuu.:
'/IFT^FlfJE GRAVEL
BACKFUISHING REQUtREMCNTSt
ISeeM. PER SO. FOOT
40-60 BS.L
BACK-FLUSH
CONNECTION
zSQUARE HOLLOW /
CLAY TILES
i-Z' STEEL
PIPE
2. Sand filter for removal of silt and other fine matter.
21
to five days and is at best haphazard. Sodium thiosulfate (0.05 gms. per gallon of water for 7 p.p.m. chlorine) is widely used for chlorine removal but it frequently breaks down and results in a drastic drop in
pH. If sodium thiosulfate is used, overtreatment must
be avoided and calcium carbonate should also be
added. A number of commercial chlorine-neutralizing
preparations are also available but are much more
expensive than thiosulfate.
SILT turbidity: Water from lakes and streams
is frequently very turbid. This problem can be overcome by use of a sand filter ( Figure 2 ) . The principal
requirements are a bed of sand and a back-flushing system.
FLOAT SWITCH FOR PUMP SUPPLY OR
FLOAT VALVE FOR ORAVITY SUPPLY..
APPROXIMXTE R/TE OP PILTR/(noi4
2&RM.PER SaFOOT
-.2 FT 8 AND.;'
\o,i X nuu.:
'/IFT^FlfJE GRAVEL
BACKFUISHING REQUtREMCNTSt
ISeeM. PER SO. FOOT
40-60 BS.L
BACK-FLUSH
CONNECTION
zSQUARE HOLLOW /
CLAY TILES
i-Z' STEEL
PIPE
2. Sand filter for removal of silt and other fine matter.