Aquasafra Water Quality Standards
1. Temperature – Ideal growth at 82º
90+ Stressed – expect beginning of mortalities over 95º if in this range for several days.
85 to 89 Slower growth- Limit handling/ moving of fish in this range.
81F to 83F Ideal for grow out, 82 is optimal.
80 to 75 Slower growth- Limit handling/ moving of fish in this range.
60 to 55 Stressed – expect beginning of mortalities if in this range for several days.
2. Ammonia – Ideally less than 0.03 ppm NH3
0.04 to 0.05 – reduce feed by 1/4
0.05 to 0.06 – reduce feed by 1/2
0.07 or higher – stop feeding
0.09 or higher – danger!!! lower pH to 7.0 by adding phosphoric acid or other available acid
3. Nitrite – ideally less than 0.4 ppm (if Chloride /Cl–/ is below 10ppm)
0.5 to 0.6 ppm – reduce feed by 1/4
0.6 to 0.7 ppm – reduce feed by 1/2
1 ppm – danger!!! Stop feeding
If nitrite level does not decrease to 0.6 ppm after 5 days at 1/2 feed – salt to 100 ppm NaCl (if no plants in system) as a temporary fix, and resume feeding at a rate that will keep nitrite below 2 ppm
Check that O2 is above 6, pH has been at least 7.4 or higher, Check carbonate – should be above 200 ppm. Check Biofilter is circulating properly (no stagnant dead zones)– add more beads/biomedical if everything else has been tried.
4. pH – OK range between 7.2 to 7.7,
Optimum level is 7.6, – unless biofilter and NH3 levels are Unstable,
(“Unstable” = NH3 levels testing above 0.05, or spiking up and down every few days)
If unstable, desired pH level is 7.3
If NH3 above 0.09 to 0.1 – lower pH to 7 (or as low as 6.5 to get NH3 to safe level)
For RAS systems: If pH is Lower than 7.4 – Raise the pH by Adding lime/bicarb/ (CAOH/ CAO) or some form of Hydroxide (OH) to the biofilter bead area at the rate of ~1/8 lb. of lime per pound of the total daily amount of feed fed. If one treatment keeps pH in desired range after one day then stop adding lime. If pH keeps dropping each day, keep adding each day until the pH rises to a pH of 7.6
7.4 to 7.5 – cut lime/bicarb by 1/2 (add 1/8th lb. of lime / pound of daily total of feed)
7.6 or above – stop adding lime/bicarb.
7.7 or higher add enough phosphoric acid (or equivalent) to the beginning of the Biofilter, to bring the pH back to 7.4
If amount of buffer needed to keep pH constant is increasing relative to feed rate, likely is a CO2 problem.
(When adding acid – put 50 mL ~ ¼ cup, in five gallons of water mix well, and then pour this acidified water slowly into the biofilter, add ¼ of bucket, wait 15 minutes, check pH, add another ¼ of the bucket, wait 15 more minutes. Keep checking pH and adding acid until pH is in desired range.)
CAUTION: WHEN ADDING ACID – ALLWAYS ADD ACID TO WATER NEVER WATER TO ACID!! Put water in bucket first, then put in the acid.
When handling acid: Always ware safety goggles and acid proof gloves.
5. Carbon Dioxide (when O2 is at saturation ~7.5 to 8PPM O2 for 80º water),
Ideally keep below 6 but up to 15 PPM is OK if dissolved CO2 is at saturation.
Over 15 ppm – reduce feed by 1/4
Over 30 ppm or higher – reduce feed by 1/2
Over 40 PPM – Stop feeding
If O2 is below saturation, (less than 8.2 ppm at 78 degrees) reduce upper level of CO2 range by % O2 levels are below O2 saturation.
i.e., If O2 = 6 PPM, reduce CO2 maximum levels by 25% – Max CO2 = 11 PPM If CO2 is consistently high, improve aeration to improve CO2 stripping / or increase size of stripping tower. If high CO2, don’t use Calcium Carbonate as a buffer, as it adds CO2.