Calculations:
Salt (NaCl) is currently the cheapest source of chloride for most producers. Addition of 4.5 lbs of salt per 1 acre-foot of water increases the chloride level 1 ppm. Some practical examples are presented below to illustrate how a farmer can manage to effectively eliminate nitrite induced losses of stock.
FIRST:
: Measure the chloride level in the existing pond or water source. This is typically done using an inexpensive and simple water quality kit or test strip.
SECOND:
: Calculate how much salt by weight is necessary to bring the chloride level to 60 ppm or higher. For example:
Problem 1
- The pond has 60 ppm chlorides
- Need 100 ppm chlorides
- Must increase 40 ppm chlorides
- Pond is 12 acres with 4 feet average depth
- 4.5 lbs. of salt X 40 ppm chlorides needed = 180.0 lbs. of salt/acre-foot
- 180.0 lbs. of salt/acre-foot X 48 acre feet = 8640 lbs.
- 8640 lbs. ÷ 2000 lbs. = 4.32tons => Add 4.5 Tons of Salt
OR
Problem 2
- Chloride 60 ppm
- Pond 15 acres with 4.0 foot average depth
- 8 ppm nitrite X 9 = 72 ppm chloride required for protection
- 72 ppm chloride needed - 60 ppm chloride present = 12 ppm chloride to add
- 12 ppm chloride X 4.5 lbs. salt/acre-foot = 54 lbs. salt/acre-foot
- 54 lbs. salt/acre-foot X 60 acre-feet in pond = 3240 lbs.
- 3240 lbs ÷ 2000 lbs = 1.62 tons => Add 2 Tons of Salt
Refer to Chloride/Nitrite table below for additional information on salt requirements for protection against Nitrite Poisoning.
Custom delivery trucks are available for large quantities of salt delivered in Alabama. These trucks can haul and dispense up to 18 tons per load. Prices will vary between $90 and $100 per ton delivered (2008 prices). Incorporate into ponds using paddle wheel aeration equipment. Broadcast evenly across pond if stressed fish are being treated for nitrite poisoning. Generally, 24 hours are required for full incorporation.
Remember:
- Prevention is the key and is much less expensive than correcting an existing problem.
- Maintain a minimum of 60 ppm chlorides at all times in commercial catfish ponds.
- Always maintain at least a 9 to 1 chloride to nitrite ratio. Many use a 10:1 ratio.
Salt Addition Reference Table for Prevention of Nitrite Poisoning
To use this table: First, measure chloride and nitrite levels in the pond. Then, find the corresponding nitrite row and chloride column on the table. At the intersection of the row and column is the number of pounds of salt needed per acre/foot to provide minimal protection.
Author:
Jesse A. Chappell. Extension Fisheries Specialist, Assistant Professor
