Great record keeping as Bruce stated!
I used to work for Aquatic Eco Systems, the world's largest aquaculture supply company and here are a few of my notes from those days:
Consumers of oxygen...
1. Fish
a.) 0.45 lbs of O2/100 lbs of fish/day.
b.) 91 grams of O2/1 lbs of feed fed.
2. BOD (Biochemical Oxygen Demand)
a.) 5.29 grams of O2/KG of Fish @ 1% weight
...one can assume a 70% removal rate
which leaves 30% of BOD to meet.
example: 5.29 g of O2 x 0.3 = 1.587 g
of BOD.
3. Bacteria
a.) 4.25 g of O2/g of ammonia denitrified.
b.) 13.1 grams of ammonia/lb of food fed.
Full example:
10,000 lbs of fish fed 2% body weight/day
a.) Fish requirements
* 10,000 x 2% = 200 lbs of feed
* 200/2.2 = 90.9 kg of feed
* 90.0 x 200 = 18,182 g of O2 required
b.) BOD Requirements
* 90.9 kg x 529= 48,086 g
* 30% x 48,086 = 14,426 g of BOD
c.) Bacteria
* 13.1 g x 200 lbs of food = 2620 g of
ammonia
* 2620 grams of ammonia x 4.25 g of O2
= 11,135 g of ammonia
Total oxygen required = 18,182 + 14,426 + 11,135 = 43,743 g.
43,743/453.6 = 96.4 lbs of O2 per 200 lbs of feed.
So, the question by Bruce of "Have you decreased the feeding schedule at all as the temp climbs?" is so important.
As the temperature increases the oxygen retained in the system decreases. Obviously you are not managing 10,000 lbs of fish but this is an extreme example of some of the things that are going on in under the water.
