Aeration

Gordon

We opted to dispense with aeration via separate aerators and air stones, and find that using a 1/2 horsepower return pump (interchangeable with our output pumps), adding an end cap on the return water line (1-1/2" PVC) with numerous 1/4" holes, gives us a great dissolved oxygen boost as the water returns to the fish tanks.

Tom's tests showed a 25% DO boost when the water passed through the gravel beds (tested from the common return buckets for each node), and an additional 25% boost coming from the return lines. He says our DO runs from 5.63 to 6.39 (using a Hach digital titration tester). I'd have to dig through our older references to see what the industry describes as optimum DO range, as we generally use the "how do the fish look/act" method Darren Hanson describes. Perhaps someone has those figures at hand.

Paula